Chemical catalyst-microorganism carbon sequestration system for improving utilization efficiency of H2 and application of chemical catalyst-microorganism carbon sequestration system

Abstract

The invention relates to a chemical catalyst-microorganism carbon sequestration system for improving H2 utilization efficiency and application thereof, and belongs to the field of biochemical engineering. According to the method, the chemical catalyst with H2 activation performance and the acetogenic bacteria are cultured in the culture medium containing H2 and CO2, so that the utilization efficiency of H2 and CO2 can be remarkably improved, the concentration of ethanol and acetic acid can be remarkably improved, the acid-alcohol ratio is reduced, and the biomass is also remarkably improved. According to the hydrogenase-like chemical catalyst and the acetogenic bacterium carbon sequestration system provided by the invention, the H2 utilization and carbon sequestration efficiency are remarkably improved, and the ethanol content is increased, so that the added value of a product is increased, and the hydrogenase-like chemical catalyst and the acetogenic bacterium carbon sequestration system have important significance on industrial implementation of CO2 biological immobilization taking H2 as an energy source, and have wide application scenes and economic values.

Description

Technical Field

[0001] The present application relates to a chemical catalyst-microbial carbon fixation system for improving the utilization efficiency of H2 and its application, belonging to the field of biochemistry. Background Art

[0002] Biological carbon fixation is an important functional basis for the stability and development of the biosphere. In the context of the increasingly severe environmental crisis and energy shortage problems, its technical and engineering significance has gradually attracted attention and emphasis. Using carbon-fixing microorganisms as a platform to catalytically fix CO2 in various energy forms and then fix it into various energy sources and chemicals can effectively combine carbon fixation and emission reduction with green synthesis, which is of great significance for alleviating resource crises, reducing environmental pollution, and promoting social sustainable development.

[0003] Acetogens are a class of obligate anaerobic chemoautotrophic microorganisms. They synthesize acetyl-CoA and derivatives of acetyl-CoA, such as acetic acid, ethanol, etc., through the linear Wood-Ljungdahl pathway (also known as the reductive acetyl-CoA pathway) to achieve the process of terminal electron acceptance and energy conservation and carry out autotrophic growth. Different from the Calvin cycle and other pathways that fix CO2 through cyclic reactions, the Wood-Ljungdahl pathway has less dependence on central metabolism or is less interfered by it, and has unique advantages from the perspective of high throughput required for industrial applications.

[0004] All naturally occurring acetogens are CO2-fixing, anaerobic, autotrophic, and non-methanotrophic. Since CO2 can only be used as a carbon source and its fixation requires additional energy, acetogens use the energy released by H2 or CO oxidation to generate reducing power for CO2 fixation and ATP synthesis.

[0005] Using CO as an energy donor, acetogens fix CO2 and produce ethanol and other products, which have been industrialized (Nat Biotech 2022, 40: 335). However, when using CO as an energy source to produce ethanol, two-thirds of the carbon will be discharged in the form of CO2, resulting in poor carbon atom economy. Therefore, adding H2 can provide energy to re-fix the CO2 generated by CO oxidation and promote carbon recycling.

[0006] Using H2 as an energy donor for acetogens to fix CO2 is the future development trend, but there are currently great deficiencies, mainly manifested in low gas utilization and energy conversion efficiency, long carbon fixation and circulation periods, low product yield and productivity, only producing acetic acid and not producing ethanol, etc., resulting in low added value of products, which greatly limits the efficient biological conversion and utilization of CO2.

[0007] When acetogenic bacteria use H2 as an energy donor, hydrogenase plays a key role; hydrogenase captures H2 and catalyzes the oxidation of H2. Through electron disproportionation reactions, coenzymes such as reduced ferredoxin and NAD(P)H are produced for the conversion and utilization of CO2. Since the solubility of H2 in the liquid phase is extremely low, it is difficult for intracellular hydrogenase to capture H2, affecting the continuous and efficient supply of coenzymes and limiting the biological fixation efficiency of CO2.

[0008] Through artificial design and modification, integrating artificial functional material components into biological metabolic activities, supplementing or even replacing some biological components, constructing microbial-artificial material chimeras, and realizing the functional chimerism of "biology-materials", are expected to play a role in major directions such as the efficient conversion and utilization of energy and artificial carbon fixation.

[0009] For example, a chimeric system of the non-photosynthetic autotrophic microorganism Moorella thermoacetica and the semiconductor material cadmium sulfide has been reported. Cadmium sulfide nanoparticles on the cell surface of this chimeric system capture solar energy to generate extracellular electrons, and microbial cells use these electrons to generate reducing power extracellularly or intracellularly, and fix CO2 through the Wood-Ljungdahl pathway, ultimately achieving light-driven acetic acid synthesis (Proc Natl Acad Sci USA. 2016, 113(42): 11750-11755).

[0010] Another example is that indium phosphide particles are assembled onto the surface of Saccharomyces cerevisiae cells by virtue of the interaction between polyphenols and the cell wall, constructing a chimera of Saccharomyces cerevisiae and the semiconductor material indium phosphide. Yeast cells use the nanoparticles on the surface to obtain photo-generated electrons and use them for the regeneration of the redox cofactor NADPH, promoting the efficient synthesis of the metabolite shikimic acid (Science 2018, 362, 813-816).

[0011] Another example is that East China Normal University reported an in vivo non-metallic inorganic semiconductor-microorganism hybrid system. The semiconductor material C3N4·QDs has good biocompatibility and appropriate size, and enters Escherichia coli cells by endocytosis to form an in vivo inorganic semiconductor-microorganism hybrid system. Inside Escherichia coli cells, a C3N4·QDs / NAD + junction is formed through unique π-π electron conjugation, directly photocatalyzing inside the bacteria to achieve efficient hydrogen production.

[0012] The hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase, and it contains a carrier and an active center. The carrier is usually carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite, etc. The active center is generally metal nanoparticles such as iron, cobalt, nickel, palladium and platinum. The carrier can increase the stability of the hydrogenase-mimicking catalyst, accelerate electron transfer, and be used for the immobilization of the metal active center. The hydrogenase-mimicking catalyst can achieve efficient activation of hydrogen under normal temperature and pressure.

[0013] When the hydrogenase-mimicking catalyst is applied to the gas fermentation system of acetic acid-producing bacteria, it can efficiently activate hydrogen extracellularly, and the extracellular electrons generated can be transferred to the intracellular to generate reducing power by electron carriers or acceptors such as riboflavin, metal ions, and respiratory enzymes, which is expected to achieve efficient utilization of H2 and efficient fixation of CO2.

[0014] No research or application on the hybrid system of the hydrogenase-mimicking catalyst and acetic acid-producing bacteria has been found in the patents and literature disclosed in the prior art. Summary of the Invention

[0015] In order to solve the problem of low efficiency of H2 utilization and CO2 fixation by acetic acid-producing bacteria, the present invention provides a chemical catalyst-microbial carbon fixation system for improving the efficiency of H2 utilization and its application. In this application, the efficient hydrogen activation ability of the hydrogenase-mimicking catalyst is combined with acetic acid-producing bacteria to construct a hybrid system of the hydrogenase-mimicking catalyst and acetic acid-producing bacteria, which can achieve efficient utilization of H2 and efficient fixation of CO2.

[0016] According to one aspect of the present application, a carbon fixation system for efficiently utilizing H2 is provided. The carbon fixation system includes a composition, and the composition includes a hydrogenase-mimicking catalyst and acetic acid-producing bacteria; further preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528 and Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T.

[0017] According to another aspect of the present application, a composition is provided, including a hydrogenase-mimicking catalyst and acetic acid-producing bacteria; further preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528 and Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T.

[0018] According to another aspect of the present application, there is provided one of the following uses of the hydrogenase-mimicking catalyst:

[0019] 1) Use for promoting the efficiency of microorganisms in utilizing H2:

[0020] 2) Use for promoting carbon fixation by microorganisms;

[0021] 3) Use for promoting the fixation of CO2 by microorganisms;

[0022] 4) Use for promoting or increasing the biomass or cell mass of microorganisms;

[0023] 5) Use for promoting the yield or production efficiency of microbial metabolites;

[0024] 6) Use for promoting the yield or production efficiency of microorganisms in producing ethanol, butanol, hexanol, acetic acid, butyric acid, hexanoic acid, lactic acid, 2,3-butanediol, acetone, isopropanol, or 3-hydroxybutyric acid;

[0025] The composition includes a hydrogenase-mimicking catalyst and acetic acid-producing bacteria; further preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots, or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium, and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst, and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and grow autotrophically; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei, and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061, or Clostridium carboxidivorans P7 DSM15243T; further preferably, the metabolite is a primary metabolite or a secondary metabolite of the microorganism; further preferably, the metabolite includes one or more of acetic acid, ethanol, butyric acid, butanol, hexanoic acid, and hexanol.

[0026] According to another aspect of the present application, a method for a microorganism to produce a metabolite is provided, including the step of using the above carbon fixation system or the above composition; further preferably, the metabolite is a primary metabolite or a secondary metabolite of the microorganism; further preferably, the metabolite includes one or more of acetic acid, ethanol, butyric acid, butanol, hexanoic acid, and hexanol.

[0027] According to another aspect of the present application, a method for improving the H2 utilization efficiency of a microorganism is provided, including the step of adding a hydrogenase-mimicking catalyst during the production or fermentation process of the microorganism, such as before inoculation in fermentation culture or at a certain stage after inoculation; the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots, or iron oxide; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium, and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-iron oxide hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst, and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and grow autotrophically; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei, and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061, or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gases as the main gas sources; further preferably, the gas source composition is H2, CO2, or the composition is H2, CO2, and CO, or the composition is H2, CO; further preferably, the proportion of H2 is 10% to 90%.

[0028] According to another aspect of the present application, a method for promoting microbial carbon fixation is provided, which includes the step of adding a hydrogenase-mimicking catalyst during the production or fermentation process of the microorganism, for example, before the inoculation of fermentation culture or at a certain stage after inoculation; the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528 and Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gases as the main gas sources; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is H2, CO; further preferably, the proportion of H2 is 10% to 90%.

[0029] According to another aspect of the present application, a method for promoting or improving the carbon fixation efficiency of microorganisms is provided, which includes the step of adding a hydrogenase-mimicking catalyst during the production or fermentation process of the microorganisms, such as before inoculation in fermentation culture or at a certain stage after inoculation; the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528 and Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gases as the main gas sources; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is further H2, CO; further preferably, the proportion of H2 is 10% to 90%.

[0030] According to another aspect of the present application, a method for producing ethanol by microorganisms is provided, which includes the step of using the above carbon fixation system or the above composition; further preferably, it includes the process of fermentation in an environment containing H2 and C1 gases; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is further H2, CO; further preferably, the proportion of H2 is 10% to 90%; further preferably, it includes the stages of strain activation, adaptive subculture and fermentation culture, and the step of adding the hydrogenase-mimicking catalyst during the fermentation culture stage.

[0031] According to another aspect of the present application, a method for producing acetic acid by microorganisms is provided, which includes the steps of the above-mentioned carbon fixation system or the above-mentioned composition; further preferably, it includes a fermentation process carried out in an environment containing H2 and C1 gas; further preferably, the gas source composition is H2, CO2, or the composition is H2, CO2 and CO, or the composition is H2, CO; further preferably, the proportion of H2 is 10% to 90%; further preferably, it includes the stages of strain activation, adaptive subculture, and fermentation culture, and the step of adding the hydrogenase-mimicking catalyst in the fermentation culture stage.

[0032] Optionally, in the adaptive subculture stage, H2 and C1 gas are used as the main gas sources, and the content of H2 is 20% to 80%, for example, it can be 20%, 30%, 40%, 50%, 60%, 70%, or 80%. The C1 gas can be CO or CO2, and the gas source can be H2 and CO2, or the gas source can be H2, CO, and CO2, or the gas source can be H2, CO.

[0033] Optionally, in the fermentation culture stage, H2 and C1 gas are used as the main gas sources, and the content of H2 is 20% to 80%, for example, it can be 20%, 30%, 40%, 50%, 60%, 70%, or 80%. The C1 gas can be CO or CO2, and the gas source can be H2 and CO2, or the gas source can be H2, CO, and CO2, or the gas source can be H2, CO.

[0034] It should be noted that the present invention improves the utilization efficiency of H2, thereby improving the fixation efficiency of CO2 in the environment and increasing the yield of the target product. Different proportions of CO2 in the C1 gas raw material and different target products result in different requirements for the proportion of H2. Therefore, for those skilled in the art, it can be understood that depending on the different proportions of CO and CO2 in the C1 gas raw material and the differences in the target products, the proportion of H2 from 10% to 90%, for example, it can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%, may all be applicable to this solution. The C1 gas can be CO or CO2, and the gas source can be H2 and CO2, or the gas source can be H2, CO, and CO2, or the gas source can be H2, CO.

[0035] Optionally, the hydrogenase-mimicking catalyst is added to the culture system, and the content of the hydrogenase catalyst is greater than 0.05 g / L, and the further content can be greater than 0.1 g / L, can be greater than 0.2 g / L, and the range can be 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, or 0.5 g / L.

[0036] It should be noted that the above carbon fixation products are directly or indirectly synthesized by acetogenic bacteria through the Wood-Ljungdahl pathway. It is understandable for those skilled in the art that in the process of microbial carbon fixation of the carbon fixation system provided by this application, other products besides natural products such as acetic acid and ethanol can be synthesized by gas fermentation through the transformation of strains. Therefore, the carbon fixation products referred to in this application are not limited to the above products.

[0037] As known to those skilled in the art, some acetogenic bacteria can grow autotrophically using CO and synthesize products. During this process, a part of CO will be converted into CO2 and discharged. The present invention improves the utilization efficiency of H2, and thus improves the fixation efficiency of CO2 in the environment. Therefore, it is understandable for those skilled in the art that the solution of this application can also be applied to the process of H2 and CO fermentation.

[0038] It should be noted that according to the different activities of the catalyst and different fermentation methods and techniques, the dosage of the hydrogenase-mimicking catalyst to achieve the best effect may be different. The protection scope of this solution should not be limited by the catalyst content in the system.

[0039] The beneficial effects of this application include but are not limited to:

[0040] 1. The carbon fixation system for efficiently utilizing H2 according to this application significantly improves the utilization efficiency of H2 and CO2 gases, significantly increases the concentration of acids and alcohols in the products, reduces the acid-alcohol ratio, and also significantly increases the biomass of acetogenic bacteria.

[0041] 2. The carbon fixation system for efficiently utilizing H2 according to this application, compared with only using acetogenic bacteria, in a preferred embodiment, the biomass is increased by 1 time, the acetic acid production is increased by up to 60%, and the ethanol concentration is increased by as much as 20 times, reaching 45 g / L, achieving significant technological progress compared with the existing technical solutions.

[0042] 3. The carbon fixation system for efficiently utilizing H2 according to this application significantly improves the utilization efficiency of H2 and CO2, increases the ethanol content and thus increases the added value of the product, which is of great significance to the industrial implementation of CO2 biological fixation using H2 as the energy source, and has broad application scenarios and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of this application and constitute a part of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0044] Figure 1 are the in vitro model experiment results of the reduction of p-nitrophenol by 7 hydrogenase-mimicking catalysts involved in this application;

[0045] Figure 2 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with those of the Co@NCNT-Clostridium ljungdahlii hybrid system constructed by adding different amounts of Co@NCNT catalyst at a 50-ml shake-flask fermentation scale (circles: Clostridium ljungdahlii; squares: Co@NCNT-Clostridium ljungdahlii hybrid system containing 2.5 mg of catalyst; upright triangles: Co@NCNT-Clostridium ljungdahlii hybrid system containing 5 mg of catalyst; inverted triangles: Co@NCNT-Clostridium ljungdahlii hybrid system containing 10 mg of catalyst; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0046] Figure 3 Results of the growth and metabolite characteristics of fermenting gas raw materials with different H2 ratios using the Co@NCNT-Clostridium ljungdahlii hybrid system at a 50-ml shake-flask fermentation scale (circles: CO2:H2 = 4:6; triangles: CO2:H2 = 3:7; squares: CO2:H2 = 1:3);

[0047] Figure 4 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with those of the Pt@Fe3O4-Clostridium ljungdahlii hybrid system at a 50-ml shake-flask fermentation scale (circles: Clostridium ljungdahlii; squares: Pt@Fe3O4-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0048] Figure 5 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with those of the Fe@NCNT-Clostridium ljungdahlii hybrid system at a 50-ml shake-flask fermentation scale (solid circles: Clostridium ljungdahlii; open circles: Fe@NCNT-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0049] Figure 6 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with those of the Ni@NCNT-Clostridium ljungdahlii hybrid system at a 50-ml shake-flask fermentation scale (circles: Clostridium ljungdahlii; inverted triangles: Ni@NCNT-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0050] Figure 7Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with the Ni@SiO2-Clostridium ljungdahlii hybrid system under a 50 ml shake flask fermentation scale in Example 6 of this application (solid circles: Clostridium ljungdahlii; semi-hollow circles: Ni@SiO2-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0051] Figure 8 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with the Co@SiO2-Clostridium ljungdahlii hybrid system under a 50 ml shake flask fermentation scale in Example 7 of this application (solid circles: Clostridium ljungdahlii; hollow squares: Co@SiO2-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0052] Figure 9 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with the Fe@SiO2-Clostridium ljungdahlii hybrid system under a 50 ml shake flask fermentation scale in Example 8 of this application (circles: Clostridium ljungdahlii; diamonds: Fe@SiO2-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0053] Figure 10 Results of comparing the growth and metabolite characteristics of Clostridium autoethanogenum fermentation with the Co@NCNT-Clostridium autoethanogenum hybrid system under a 50 ml shake flask fermentation scale in Example 9 of this application (hexagons: Clostridium autoethanogenum; triangles: Co@NCNT-Clostridium autoethanogenum hybrid system; A is the growth status of Clostridium autoethanogenum cells; B is the acetic acid content; C is the ethanol content);

[0054] Figure 11 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with the Co@NCNT-Clostridium ljungdahlii hybrid system under a 50 L fermenter scale in Example 10 of this application (circles: Clostridium ljungdahlii; triangles: Co@NCNT-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0055] Figure 12 Results of comparing the growth and metabolite characteristics of Clostridium ljungdahlii fermentation with the Co@NCNT-Clostridium ljungdahlii hybrid system under an optimized 50 L fermenter scale in Example 11 of this application (circles: Clostridium ljungdahlii; inverted triangles: Co@NCNT-Clostridium ljungdahlii hybrid system; A is the growth status of Clostridium ljungdahlii cells; B is the acetic acid content; C is the ethanol content);

[0056] Figure 13This is the result of comparing the growth and metabolite characteristics of Clostridium carboxidivorans in a 50 ml shake flask fermentation scale with the Co@NCNT-Clostridium carboxidivorans hybrid system in Example 12 of this application (solid graph: Clostridium carboxidivorans; hollow graph: Co@NCNT-Clostridium carboxidivorans hybrid system; the circle in Figure A represents the growth status of Clostridium carboxidivorans, the circle in Figure B represents the acetic acid concentration; the triangle in Figure B represents the butyric acid concentration; the rhombus represents the caproic acid concentration; the circle in Figure C represents the ethanol concentration; the triangle in Figure C represents the butanol concentration; the rhombus in Figure C represents the hexanol concentration). Detailed implementation mode

[0057] The following describes this application in detail with reference to the examples. However, this application is not limited to these examples. Unless otherwise specified, the raw materials and catalyst preparation raw materials in the examples of this application are all purchased through commercial channels.

[0058] The following makes a detailed description of the solution of this application with reference to specific examples.

[0059] The strains used in this application are Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061, and Clostridium carboxidivorans P7 DSM15243T (purchased from the German Collection of Microorganisms and Cell Cultures).

[0060] All the preserved strains need to be activated before fermentation: The corresponding strains are inoculated at an inoculation amount of 10% into 50 mL PETC gas medium (synthesis gas containing 20% - 90% CO, and the rest is CO2 and H2, with a pressure of 0.15 - 0.2 MPa), and cultured at a constant temperature of 37°C for 48 h for activation.

[0061] The liquid PETC medium used for fermentation contains: macronutrients (ammonium chloride 0.5 g / L, potassium chloride 0.2 g / L, magnesium sulfate heptahydrate 0.4 g / L, sodium chloride 1 g / L, potassium dihydrogen phosphate 0.2 g / L, sodium tungstate 0.005 g / L), micronutrient metals (manganese chloride tetrahydrate 0.015 g / L, manganese sulfate monohydrate 0.015 g / L, ferrous sulfate 0.04 g / L, cobalt chloride hexahydrate 0.004 g / L, zinc sulfate heptahydrate 0.004 g / L, nickel chloride hexahydrate 0.0004 g / L, sodium molybdate 0.004 g / L, sodium selenate 0.002 g / L), magnesium chloride 0.4 g / L, calcium chloride monohydrate 0.02 g / L, calcium chloride 0.2 g / L, nitrilotriacetic acid 0.002 g / L, resazurin 0.001 g / L, yeast extract 1 g / L, L-cysteine 0.25 g / L, 0.1% vitamin mixture (biotin 2 mg / L, folic acid 2 mg / L, vitamin B6 10 mg / L, thiamine 5 mg / L, riboflavin 5 mg / L, calcium pantothenate 5 mg / L, lipoic acid 5 mg / L, p-aminobenzoic acid 5 mg / L, cyanocobalamin 5 mg / L, nicotinic acid 5 mg / L).

[0062] Cell biomass was evaluated by measuring the absorbance at 600 nm (OD 600nm ). Due to the magnetism of the catalyst support or the metal of the catalytic center, after sampling, the catalyst was removed by magnetic adsorption, and then the OD of the culture broth was measured 600nm .

[0063] The product analysis method was high performance liquid chromatography HPLC. The instrument used was Agilent HPLC 1260 (differential refractive index). The chromatographic conditions included: the chromatographic column was Aminex HPX-87H Column; the mobile phase was 5 mM sulfuric acid; the flow rate was 0.5 mL / min; the injection volume was 10 μL; the column temperature was 55 °C; differential refractive index detector. The sample preparation method included: the fermentation broth was centrifuged at 4 °C and 12000 rpm for 5 min, the supernatant was taken and appropriately diluted, and then filtered through a 0.22 μm microporous filter membrane for HPLC analysis.

[0064] The hydrogenase-mimicking catalysts used in this application, such as Pt@Fe3O4, Co@NCNT, Ni@NCNT, Fe@NCNT, Fe@SiO2, Ni@SiO2, Co@SiO2, etc., can all be prepared by known methods in the prior art or obtained through commercial channels. For example, they can be prepared as described in the references (Physicochemical and Engineering Aspects, 2004, 245(1-3), 15-19; Journal of Energy Chemistry, 2021, 52, 12-19; ACS Sustainable Chemistry & Engineering, 2018, 6(10), 13287-13295.). At the same time, the present invention provides the following specific methods, which are preferred but not exclusive:

[0065] Preparation of the hydrogenase-mimicking catalyst Pt@Fe3O4 of platinum-ferroferric oxide:

[0066] 1) Preparation of Fe3O4 nanoparticles: Weigh 2.35 g of FeCl3·6H2O and 0.86 g of FeCl2·4H2O and place them in a 250 mL Schlenk flask. Add 100 mL of deionized water to dissolve. Slowly drop 13% ammonia water under stirring until the pH of the reaction solution rises to 10. The reaction system changes from a solution to a suspension, and the color changes from orange-red to reddish-brown and finally to black. Collect the black powder by centrifugation, wash it with deionized water until the pH of the supernatant no longer changes, and freeze-dry to obtain Fe3O4 nanoparticles.

[0067] 2) Preparation of amino-functionalized Fe3O4 nanoparticles (Fe3O4-NH2): Weigh 0.3 g of Fe3O4 nanoparticles, disperse them ultrasonically in 250 mL of deionized water, heat to 60 °C, add 0.2 mL of APTES under stirring, continue stirring for 30 min, dropwise add 0.5 mL of ammonia water, and continue reacting for 1 h. Collect the solid by centrifugation, wash it successively with deionized water and flowing CO2 gas, and vacuum-dry to obtain black magnetic powder.

[0068] 3) Under nitrogen protection, disperse 0.2 g of Fe3O4-NH2 nanoparticles into the freshly prepared sodium borohydride solution. Dropwise add 1 mL of H2PtCl6 solution (10 mg / mL) under stirring, stir for 6 h, collect the black powder by centrifugation, wash it successively with deionized water and ethanol, and vacuum-dry to obtain Pt@Fe3O4 nanoparticles.

[0069] Preparation of the hydrogenase-mimicking catalyst Co@NCNT of cobalt-carbon nanotube:

[0070] 1) Weigh 0.4 g of melamine, 0.4 g of citric acid monohydrate, and 0.3 g of Co(NO3)2·6H2O and place them in a 500 mL round-bottom flask. Add 200 mL of deionized water and react overnight at 85 °C to obtain a pink powder.

[0071] 2) Spread 1 g of the pink powder evenly on a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, calcine at 700 °C for 1 h, then continue to heat to 800 °C and calcine for 0.5 h to obtain the Co@NCNT material.

[0072] Preparation of nickel-carbon nanotube hydrogenase-mimicking catalyst Ni@NCNT:

[0073] 1) Weigh 0.4 g of melamine, 0.4 g of citric acid monohydrate, and 0.27 g of Ni(NO3)2·6H2O and place them in a 500 mL round-bottom flask. Add 200 mL of deionized water and react overnight at 85 °C to obtain a light green powder.

[0074] 2) Spread 1 g of the light green powder evenly on a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, calcine at 700 °C for 1 h, then continue to heat to 800 °C and calcine for 0.5 h to obtain the Ni@NCNT material.

[0075] Preparation of iron-carbon nanotube hydrogenase-mimicking catalyst Fe@NCNT:

[0076] 1) Weigh 0.4 g of melamine, 0.4 g of citric acid monohydrate, and 0.42 g of Fe(NO3)3·9H2O and place them in a 500 mL round-bottom flask. Add 200 mL of deionized water and react overnight at 85 °C to obtain a yellow powder.

[0077] 2) Spread 1 g of the yellow powder evenly on a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, calcine at 700 °C for 1 h, then continue to heat to 800 °C and calcine for 0.5 h to obtain the Ni@NCNT material.

[0078] Preparation of iron-silica hydrogenase-mimicking catalyst Fe@SiO2:

[0079] 1) Weigh 0.28 g of Fe(NO3)3·9H2O and dissolve it in 3.5 mL of deionized water. Add 3 g of SiO2, ultrasonically disperse for 1 h, stir at room temperature for 8 h, rotary evaporate to remove water, and dry overnight at 80 °C.

[0080] 2) In a tube furnace, under static air, heat at a rate of 1.5 °C / min to 450 °C and calcine for 1 h to obtain the Fe@SiO2 material.

[0081] Preparation of nickel-silica hydrogenase-mimicking catalyst Ni@SiO2:

[0082] 1) Weigh 0.18 g of Ni(NO3)2·6H2O and dissolve it in 3.5 mL of deionized water. Add 3 g of SiO2, ultrasonically disperse for 1 h, stir at room temperature for 8 h, remove the water by rotary evaporation, and dry overnight at 80 °C.

[0083] 2) In a tube furnace, in static air, heat to 450 °C at a heating rate of 1.5 °C / min and calcine for 1 h to obtain the Ni@SiO2 material.

[0084] Preparation of cobalt-silica mimetic hydrogenase catalyst Co@SiO2:

[0085] 1) Weigh 0.2 g of Co(NO3)2·6H2O and dissolve it in 3.5 mL of deionized water. Add 3 g of SiO2, ultrasonically disperse for 1 h, stir at room temperature for 8 h, remove the water by rotary evaporation, and dry overnight at 80 °C.

[0086] 2) In a tube furnace, in static air, heat to 450 °C at a heating rate of 1.5 °C / min and calcine for 1 h to obtain the Co@SiO2 material.

[0087] The in vitro hydrogen activation performance of the catalyst was tested by an in vitro model experiment for the reduction of p-nitrophenol. The specific method is as follows:

[0088] 1) At room temperature, add 10 mg of the catalyst powder to a Schlenk tube, add 9 mL of pure water, ultrasonically disperse, add 1 mL of 10 mmol / L p-nitrophenol solution, displace the gas with hydrogen 3 times, protect with hydrogen, and take samples at regular intervals.

[0089] 2) Scan the absorbance value with a UV-visible spectrophotometer between 250 - 550 nm until the curve no longer changes. The scanning results are as Figure 1 . p-Nitrophenol has a characteristic absorption peak at 400 nm. After the nitro group is reduced to an amino group, the absorption peak at 400 nm gradually disappears with time. Figure 1 The results show that the prepared Pt@Fe3O4, Co@NCNT, Ni@NCNT, Fe@NCNT, Ni@SiO2, Co@SiO2, and Fe@SiO2 materials can completely catalyze the p-nitrophenol solution in 3 min, 15 min, 11 min, 20 min, 14 min, 17 min, and 20 min respectively, proving that the prepared catalyst materials can efficiently activate hydrogen.

[0090] Comparative Example 1 Gas fermentation experiment on the scale of 50 ml of Clostridium ljungdahlii DSM 13528

[0091] The activated Clostridium ljungdahlii DSM 13528 bacterial solution was transferred at an inoculation amount of 10% to another 50 mL of PETC gas medium (CO2 + H2, with a ratio of 4:6 and a pressure of 0.1 - 0.2 MPa) for adaptive cultivation until the OD 600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2 + H2, with a ratio of 4:6 and a pressure of 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to thoroughly adapt to growing with CO2 as the carbon source. The domesticated bacterial solution was then transferred at an inoculation amount of 10% to 50 mL of PETC gas medium (CO2 + H2, with a ratio of 4:6), and fermented in a shaking flask at 37°C.

[0092] Example 1 Comparative experiment on the addition amount of Co@NCNT - Clostridium ljungdahlii hybrid system catalyst

[0093] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was transferred at an inoculation amount of 10% to another 50 mL of PETC gas medium (CO2 + H2, with a ratio of 4:6 and a pressure of 0.1 - 0.2 MPa) for adaptive cultivation until the OD 600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2 + H2, with a ratio of 4:6 and a pressure of 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to thoroughly adapt to growing with CO2 as the carbon source.

[0094] 2) Weigh 2.5 mg, 5 mg, and 10 mg of Co@NCNT catalyst respectively, resuspend them with 500 μL of PETC medium, and add them to anaerobic flasks containing 50 mL of PETC medium respectively. Subsequently, each anaerobic flask was filled with CO2 + H2 gas (with a ratio of 4:6 and a pressure of 0.2 MPa).

[0095] 3) The domesticated bacterial solution from step 1) above was transferred at an inoculation amount of 10% to the above - mentioned 50 mL of PETC gas medium containing different dosages of the hydrogenase - mimicking catalyst, and fermented in a shaking flask at 37°C.

[0096] The results are as Figure 2 shown. Compared with the fermentation of Clostridium ljungdahlii, for the hybrid system fermenting CO2 + H2 with the addition of the catalyst, the cell biomass, acetic acid concentration, and ethanol concentration were all improved. At a 50 - mL scale, adding 5 mg (0.1 g / L) of the catalyst had the best effect. The biomass and acetic acid concentration increased by about 100%, and the ethanol concentration increased nearly 3 - fold, reaching 0.65 g / L. In addition, adding 0.2 g / L of the catalyst had a relatively slow growth of primary cells during fermentation, but in the later stage of fermentation, the fermentation effect was comparable to that of the 0.1 g / L catalyst, indicating that at a higher cell concentration, adding a higher dosage of the catalyst is expected to have a better fermentation effect.

[0097] Example 2 Comparative fermentation experiment of Co@NCNT-Clostridium ljungdahlii hybrid system under different CO2 and H2 ratios

[0098] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was subcultured at an inoculation amount of 10% into another 50 mL PETC gas medium (CO2 + H2, ratio 4:6 to 1:3, pressure 0.1 to 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2 + H2, ratio 4:6 to 1:3, pressure 0.1 to 0.2 MPa) for more than 2 generations to enable the strain to completely adapt to grow using CO2 as a carbon source.

[0099] 2) Weigh 5 mg of Co@NCNT catalyst respectively, resuspend each with 500 μL of PETC medium, and add them to anaerobic bottles containing 50 ml of PETC medium. Subsequently, each anaerobic bottle was filled with CO2 + H2 gas (CO2:H2 ratios were 4:6, 3:7, 1:3 respectively, pressure 0.2 MPa).

[0100] 3) The bacterial solution domesticated under the corresponding gas ratio in step 1) above was subcultured at an inoculation amount of 10% into the 50 mL PETC gas medium with different CO2 and H2 ratios, and fermented and cultured in a shaking flask at 37°C.

[0101] The results are as Figure 3 shown. At the 50 ml scale, under the three gas ratios, compared with Comparative Example 1, the biomass and acetic acid concentration increased by about 100%, and the ethanol concentration increased by 3 times, 5 times and 7 times respectively. When the CO2:H2 ratio was 1:3, it had the highest ethanol yield and the shortest growth lag period, and the ethanol concentration reached 1.1 g / L. For subsequent shaking flask fermentation experiments, the gas source with a CO2:H2 ratio of 1:3 was selected.

[0102] Comparative Example 2 50 ml scale gas fermentation experiment of Clostridium ljungdahlii DSM 13528 (CO2:H2 = 1:3)

[0103] The activated Clostridium ljungdahlii DSM 13528 bacterial solution was subcultured at an inoculation amount of 10% into another 50 mL PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 to 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 to 0.2 MPa) for more than 2 generations to enable the strain to completely adapt to grow using CO2 as a carbon source. The domesticated bacterial solution was then subcultured at an inoculation amount of 10% into the 50 mL PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.2 MPa), and fermented and cultured in a shaking flask at 37°C.

[0104] Example 3 Pt@Fe3O4 - Clostridium ljungdahlii 50 ml Scale Gas Fermentation Experiment

[0105] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was sub - transferred at an inoculation amount of 10% to 50 mL of PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then passaged in the PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to thoroughly adapt to grow using CO2 as the carbon source.

[0106] 2) Take 5 mg of Pt@Fe3O4 catalyst, resuspend it with 500 μL of PETC medium, add it to an anaerobic flask containing 50 ml of PETC medium, and then the anaerobic flask was filled with CO2 + H2 gas (CO2:H2 ratio 1:3, pressure 0.2 MPa).

[0107] 3) The domesticated bacterial solution was inoculated at 10% into the above - mentioned PETC gas medium containing the Pt@Fe3O4 catalyst, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0108] The results are as Figure 4 shown. Compared with Comparative Example 2, for the Pt@Fe3O4 - Clostridium ljungdahlii hybrid system fermenting CO2 + H2, the cell biomass and acetic acid concentration increased by more than 100%, the ethanol concentration increased by 2.3 times, and the ethanol concentration reached 0.75 g / L.

[0109] Example 4 Fe@NCNT - Clostridium ljungdahlii 50 ml Scale Gas Fermentation Experiment

[0110] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was sub - transferred at an inoculation amount of 10% to 50 mL of PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then passaged in the PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to thoroughly adapt to grow using CO2 as the carbon source.

[0111] 2) Take 5 mg of Fe@NCNT catalyst, resuspend it with 500 μL of PETC medium, add it to an anaerobic flask containing 50 ml of PETC medium, and then the anaerobic flask was filled with CO2 + H2 gas (CO2:H2 ratio 1:3, pressure 0.2 MPa).

[0112] 3) The domesticated bacterial solution was inoculated into the above-mentioned PETC gas medium containing the Fe@NCNT catalyst at 10%, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0113] The results are as Figure 5 shown. Compared with Comparative Example 2, in the Fe@NCNT-Clostridium ljungdahlii hybrid system for fermenting CO2 + H2, the cell biomass increased by about 50%, the acetic acid concentration doubled, and the ethanol concentration increased by about 2 times, reaching 0.6 g / L.

[0114] Example 5 50-ml scale gas fermentation experiment of Ni@NCNT-Clostridium ljungdahlii

[0115] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was inoculated into another 50 mL PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) at an inoculation amount of 10%, and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured for more than 2 generations in the PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) to enable the strain to fully adapt to grow using CO2 as the carbon source.

[0116] 2) Take 5 mg of the Ni@NCNT catalyst, resuspend it with 500 μL of PETC medium, and add it to an anaerobic bottle containing 50 ml of PETC medium. Subsequently, the anaerobic bottle was filled with CO2 + H2 gas (CO2:H2 ratio 1:3, pressure 0.2 MPa).

[0117] 3) The domesticated bacterial solution was inoculated into the above-mentioned PETC gas medium containing the Ni@NCNT catalyst at 10%, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0118] The results are as Figure 6 shown. Compared with Comparative Example 2, in the Ni@NCNT-Clostridium ljungdahlii hybrid system for fermenting CO2 + H2, the cell biomass increased by 60%, the acetic acid concentration increased by about 100%, and the ethanol concentration increased by 2.5 times, reaching 0.78 g / L.

[0119] Example 6 50-ml scale gas fermentation experiment of Ni@SiO2-Clostridium ljungdahlii

[0120] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was inoculated into another 50 mL PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) at an inoculation amount of 10%, and adaptively cultured until the OD 600nmAround the value of 0.2, and then subcultured for more than 2 generations in PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa) to enable the strain to completely adapt to growing with CO2 as the carbon source.

[0121] 2) Take 5 mg of Ni@SiO2 catalyst, resuspend it with 500 microliters of PETC medium, and add it to an anaerobic bottle containing 50 ml of PETC medium. Subsequently, fill the anaerobic bottle with CO2 + H2 gas (CO2:H2 ratio is 1:3 and the pressure is 0.2 MPa).

[0122] 3) Inoculate the domesticated bacterial liquid at 10% into the above PETC gas medium containing Ni@SiO2 catalyst, and culture and ferment at a constant temperature of 37 °C. Sample every 24 h to monitor the biomass and products.

[0123] The results are as Figure 7 shown. Compared with Comparative Example 2, for the Ni@SiO2 - Clostridium ljungdahlii hybrid system fermenting CO2 + H2, the cell biomass increased by about 1 time, the acetic acid concentration increased by 1.2 times, and the ethanol concentration increased by 2 times, reaching 0.67 g / L.

[0124] Example 7 50 - ml scale gas fermentation experiment of Co@SiO2 - Clostridium ljungdahlii

[0125] 1) Inoculate the activated Clostridium ljungdahlii DSM 13528 bacterial liquid at an inoculation amount of 10% and transfer it to another 50 mL PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa), and adaptively culture until the OD 600nm value is around 0.2, and then subcultured for more than 2 generations in PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa) to enable the strain to completely adapt to growing with CO2 as the carbon source.

[0126] 2) Take 5 mg of Co@SiO2 catalyst, resuspend it with 500 microliters of PETC medium, and add it to an anaerobic bottle containing 50 ml of PETC medium. Subsequently, fill the anaerobic bottle with CO2 + H2 gas (CO2:H2 ratio is 1:3 and the pressure is 0.2 MPa).

[0127] 3) Inoculate the domesticated bacterial liquid at 10% into the above PETC gas medium containing Co@SiO2 catalyst, and culture and ferment at a constant temperature of 37 °C. Sample every 24 h to monitor the biomass and products.

[0128] As described above Figure 8As shown, compared with Comparative Example 2, for the Co@SiO2-Clostridium ljungdahlii hybrid system fermenting CO2+H2, the cell biomass increased by 50%, the acetic acid concentration increased by 1.3 times, and the ethanol concentration increased by 1.5 times, reaching 0.56 g / L.

[0129] Example 8: 50 ml scale gas fermentation experiment of Fe@SiO2-Clostridium ljungdahlii

[0130] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was subcultured at an inoculation amount of 10% into another 50 mL PETC gas medium (CO2+H2, ratio 1:3, pressure 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2+H2, ratio 1:3, pressure 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to completely adapt to growing with CO2 as the carbon source.

[0131] 2) Take 5 mg of Fe@SiO2 catalyst, resuspend it with 500 μL of PETC medium, add it to an anaerobic flask containing 50 ml of PETC medium, and then fill the anaerobic flask with CO2+H2 gas (CO2:H2 ratio 1:3, pressure 0.2 MPa).

[0132] 3) The domesticated bacterial solution was inoculated at 10% into the above PETC gas medium containing Fe@SiO2 catalyst, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0133] The results are as Figure 9 shown. Compared with Comparative Example 2, for the Fe@SiO2-Clostridium ljungdahlii hybrid system fermenting CO2+H2, the cell biomass and acetic acid concentration increased by 1 time, and the ethanol concentration increased by 1.5 times, reaching 0.5 g / L.

[0134] Comparative Example 3: 50 ml scale shake flask fermentation experiment of Clostridium autoethanogenum DSM 10061

[0135] The activated Clostridium autoethanogenum DSM 10061 bacterial solution was subcultured at an inoculation amount of 10% into another 50 mL PETC gas medium (CO2+H2, ratio 1:3, pressure 0.1 - 0.2 MPa), and adaptively cultured until the OD600nm value was about 0.2, and then subcultured in the PETC gas medium (CO2+H2, ratio 1:3, pressure 0.1 - 0.2 MPa) for more than 2 generations to enable the strain to completely adapt to growing with CO2 as the carbon source. The domesticated bacterial solution was then subcultured at an inoculation amount of 10% into 50 mL PETC gas medium (CO2+H2, ratio 1:3, pressure 0.2 MPa), and cultured by shake flask fermentation at 37°C.

[0136] Example 9. 50-ml Scale Gas Fermentation Experiment of Co@NCNT-Clostridium autoethanogenum

[0137] 1) The activated Clostridium autoethanogenum DSM 10061 bacterial solution was subcultured at an inoculation amount of 10% into 50 mL of PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured for more than 2 generations in the PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa) to enable the strain to completely adapt to grow with CO2 as the carbon source.

[0138] 2) 5 mg of Co@NCNT catalyst was taken, resuspended with 500 μL of PETC medium and added to an anaerobic flask containing 50 ml of PETC medium. Subsequently, the anaerobic flask was filled with CO2 + H2 gas (CO2:H2 ratio of 1:3 and a pressure of 0.2 MPa).

[0139] 3) The domesticated bacterial solution was inoculated at 10% into the above PETC gas medium containing Co@NCNT catalyst, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0140] The results are as Figure 10 shown. Compared with Comparative Example 3, for the Co@NCNT-Clostridium autoethanogenum hybrid system fermenting CO2 + H2, the cell biomass increased by more than 1 fold, the acetic acid concentration increased by more than 50%, and the ethanol concentration increased by more than 1 fold, reaching 0.8 g / L.

[0141] Comparative Example 4. 50-L Scale Gas Fermentation Experiment of Clostridium ljungdahlii

[0142] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was subcultured at an inoculation amount of 10% into 50 mL of PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value was about 0.2, and then subcultured for more than 2 generations in the PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa) to enable the strain to completely adapt to grow with CO2 as the carbon source.

[0143] 2) Using a 5-L fermenter as the seed tank, the domesticated bacterial solution was inoculated at 10% into 4 L of PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 MPa), cultured at 37°C for 48 h, and then used as the seed liquid for culturing in a larger-scale fermenter.

[0144] 3) Select a 50 L fermenter, add 40 L of PETC gas medium, with a fermentation temperature of 37 °C, maintain the fermentation pH at around 5.6, select CO2 and H2 with a ratio of 1:3 as the main gas source, control the pressure at around 0.1 Mpa, ferment for 192 h, and take samples every 12 h to monitor the changes in biomass and product yield.

[0145] Example 10 Co@NCNT - Clostridium ljungdahlii 50 L Scale Gas Fermentation Experiment

[0146] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial solution was sub - transferred to 50 mL of PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) at an inoculation amount of 10%, and adaptively cultured until the OD 600nm value was around 0.2, and then sub - cultured for more than 2 generations in the PETC gas medium (CO2 + H2, ratio 1:3, pressure 0.1 - 0.2 MPa) to enable the strain to thoroughly adapt to growing with CO2 as the carbon source.

[0147] 2) Use a 5 L fermenter as the seed tank, transfer the domesticated bacterial solution to 4 L of PETC medium (gas supply: CO2 + H2, ratio 1:3, pressure 0.1 MPa) at an inoculation amount of 10%, and after culturing at 37 °C for 48 h, use it as the seed liquid for culturing in a larger - scale fermenter.

[0148] 3) Select a 50 L fermenter, add 40 L of PETC gas medium and 4 g of Co@NCNT catalyst. Inoculate the seed liquid into the 50 L fermenter (gas supply: CO2 + H2, ratio 1:3), with a fermentation temperature of 37 °C, maintain the fermentation pH at around 5.6, control the pressure at around 0.1 Mpa, ferment until 192 h, and supplement nitrogen source, sulfur source and Fe 2+ as needed during the process. Take samples every 12 h to monitor the changes in biomass and product yield.

[0149] The results are as Figure 11 shown. Compared with Comparative Example 4, for the Co@NCNT - Clostridium ljungdahlii hybrid system fermenting CO2 + H2 on a 50 L scale, the cell biomass and acetic acid concentration increased by about 50%. The acetic acid concentration reached 30 g / L, and the ethanol concentration reached 25 g / L, an increase of one order of magnitude.

[0150] Example 11 Co@NCNT - Clostridium ljungdahlii 50 L Scale Gas Fermentation Optimization Experiment

[0151] Based on the reaction equations for synthesizing acetic acid and ethanol from CO2 + H2, it can be seen that two molecules of CO2 and four molecules of H2 produce one molecule of acetic acid, with a CO2:H2 ratio of 1:2; two molecules of CO2 and six molecules of H2 produce one molecule of ethanol, with a CO2:H2 ratio of 1:3. At the same time, considering that the far lower amount of H2 than CO2 leads to mass transfer limitation, the proportion of H2 is further increased to 80% during the fermentation process. Meanwhile, in order to enable the intracellular metabolism of Clostridium ljungdahlii to rapidly respond to the extracellular electrons provided by the activation of H2 by the catalyst, the catalyst is added during the strain cultivation stage. Furthermore, based on the requirement for a higher cell density, the catalyst is supplemented in a 50L-scale fermenter.

[0152] The specific operations of this example are as follows:

[0153] 1) The activated Clostridium ljungdahlii DSM 13528 bacterial liquid is sub-cultured at an inoculation amount of 10% into another 50 mL PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa), and adaptively cultured until the OD 600nm value is about 0.2, and then sub-cultured for more than 2 generations in the PETC gas medium (CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 - 0.2 MPa) to enable the strain to thoroughly adapt to growing with CO2 as the carbon source.

[0154] 2) Using a 5L fermenter as the seed tank, add 4L of PETC medium and 0.4 g of Co@NCNT catalyst (gas supply is CO2 + H2, with a ratio of 1:3 and a pressure of 0.1 MPa). The domesticated bacterial liquid is transferred to the 5L fermenter at an inoculation amount of 10%. After culturing at 37°C for 48 h, it is used as the seed liquid for culturing in a larger-scale fermenter.

[0155] 3) Select a 50L fermenter, add 40L of PETC gas medium and 4 g of Co@NCNT catalyst. Inoculate the seed liquid into the 50L fermenter (gas supply is CO2 + H2, with a ratio of 1:4), the fermentation temperature is 37°C, the fermentation pH is maintained at about 5.6, the pressure is controlled at about 0.1 Mpa. During the process, nitrogen source, sulfur source and Fe 2+ are supplemented as needed. Samples are taken every 12 h to monitor the changes in biomass and product yields. When the OD 600nm reaches about 2, 4 g of Co@NCNT catalyst is supplemented, and the fermentation continues for 216 hours.

[0156] The results are as Figure 12 shown. Compared with Comparative Example 4, for the optimized Co@NCNT - Clostridium ljungdahlii hybrid system fermenting CO2 + H2 on a 50L scale, the cell biomass has increased by 100%, the acetic acid concentration has increased by 60% and reached 36 g / L, and the ethanol concentration has reached 45 g / L, an increase of 20 times.

[0157] Clostridium carboxidivorans 50 ml scale gas fermentation experiment of comparative example 5

[0158] The activated Clostridium carboxidivorans P7 DSM15243T bacterial liquid was transferred to 50 mL of PETC gas medium (synthesis gas of 20% - 90% CO, and the rest was CO2 and H2, pressure 0.15 - 0.2 MPa) at an inoculation amount of 10%, and adaptively cultured until the OD 600nm value was about 0.6, and subcultured in the PETC gas medium for more than 2 generations to make the strain completely adapt to grow with synthesis gas as the carbon source. The domesticated bacterial liquid was transferred to 50 mL of PETC gas medium (synthesis gas of 40% CO, 40% H2, 10% CO2 and N2 as the main gas source, pressure 0.2 MPa) at an inoculation amount of 10%, and fermented and cultured in a shaking flask at 37°C.

[0159] Example 12 Co@NCNT - Clostridium carboxidivorans 50 ml scale gas fermentation experiment

[0160] 1) The activated Clostridium carboxidivorans P7 DSM15243T bacterial liquid was transferred to 50 mL of PETC gas medium (synthesis gas of 20% - 90% CO, and the rest was CO2 and H2, pressure 0.15 - 0.2 MPa) at an inoculation amount of 10%, and adaptively cultured until the OD 600nm value was about 0.6, and subcultured in the PETC gas medium for more than 2 generations to make the strain completely adapt to grow with synthesis gas as the carbon source. The domesticated bacterial liquid was then transferred to 50 mL of PETC gas medium containing Co@NCNT catalyst (synthesis gas of 40% CO, 40% H2, 10% CO2 and N2 as the main gas source) at an inoculation amount of 10% simultaneously, and fermented and cultured in a shaking flask at 37°C.

[0161] 2) Take 5 mg of Co@NCNT catalyst, resuspend it with 500 μL of PETC medium, and add it to an anaerobic flask containing 50 ml of PETC medium. Subsequently, the anaerobic flask was filled with synthesis gas (40% CO, 40% H2, 10% CO2 and N2, pressure 0.2 MPa).

[0162] 3) The domesticated bacterial liquid was inoculated into the above - mentioned PETC gas medium containing Co@NCNT catalyst at 10%, and cultured and fermented at a constant temperature of 37°C. Samples were taken every 24 h to monitor the biomass and products.

[0163] The results are as Figure 13 shown. Compared with comparative example 5, for the Co@NCNT - Clostridium carboxidivorans hybrid system fermenting CO + CO2 + H2, the biomass and acetic acid concentration increased by 20%, the butyric acid and hexanoic acid concentrations nearly doubled, the ethanol and butanol concentrations increased by about 70%, and the hexanol concentration increased by 2 times.

[0164] The fermentation results of the above-mentioned examples and comparative examples are summarized in Table 1 below.

[0165] Table 1 Fermentation effects of each example compared with the comparative example

[0166]

[0167]

[0168] According to the conventional speculation of those skilled in the art, in view of the growth and metabolite characteristics exhibited by the Co@NCNT-Clostridium autoethanogenum hybrid system under 50 ml scale fermentation conditions, the Co@NCNT-Clostridium autoethanogenum hybrid system should also have higher biomass and product concentrations under larger scale fermentation conditions. Similarly, in view of the growth and metabolite characteristics exhibited by the Co@NCNT-Clostridium carboxidivorans hybrid system under 50 ml scale fermentation conditions, the Co@NCNT-Clostridium carboxidivorans hybrid system should also have higher biomass and product concentrations such as acetic acid, ethanol, butyric acid, butanol and hexanol under larger scale fermentation conditions. In view of the above-mentioned significant technical effects achieved in this application, the technical solution of this application is suitable for application in large-scale industrial production, and has broad application scenarios and economic value, which is of great significance for the industrial implementation of CO2 gas biological fixation using H2 as the energy source.

[0169] As mentioned above, only the embodiments of this application are described. The protection scope of this application is not limited by these specific embodiments, but is determined by the claims of this application. For those skilled in the art, various changes and modifications can be made to this application. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of this application shall be included within the protection scope of this application.

Claims

1. A carbon fixation system for efficiently utilizing H2, characterized in that, The carbon fixation system includes a composition, and the composition includes a hydrogenase-mimicking catalyst and acetic acid-producing bacteria; further preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T.

2. A composition, characterized in that, It includes a hydrogenase-mimicking catalyst and acetic acid-producing bacteria; further preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and carry out autotrophic growth; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T.

3. One of the following uses of the hydrogenase-mimicking catalyst, 1) The use for promoting the efficiency of microorganisms to utilize H2: 2) The use for promoting carbon fixation by microorganisms; 3) The use for promoting the fixation of CO2 by microorganisms; 4) Use for promoting or increasing the biomass or cell mass of microorganisms; 5) Use for promoting the yield or production efficiency of metabolites produced by microorganisms; 6) Use for promoting the yield or production efficiency of ethanol, butanol, hexanol, acetic acid, butyric acid, hexanoic acid, lactic acid, 2,3-butanediol, acetone, isopropanol, or 3-hydroxybutyric acid produced by microorganisms; The composition includes a hydrogenase-mimicking catalyst and acetogenic bacteria; More preferably, the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; More preferably, the hydrogenase-mimicking catalyst includes a carrier and an active center; More preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots, or iron oxide; More preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium, and platinum; More preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-iron oxide hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst, and cobalt-silica hydrogenase-mimicking catalyst; More preferably, the acetogenic bacteria are bacteria that fix CO2 through the Wood-Ljungdahl pathway and grow autotrophically; More preferably, the acetogenic bacteria are selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei, and Clostridium carboxidivorans; More preferably, the acetogenic bacteria are selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061, or Clostridium carboxidivorans P7 DSM15243T; More preferably, the metabolite is a primary metabolite or a secondary metabolite of the microorganism; More preferably, the metabolite includes one or more of acetic acid, ethanol, butyric acid, butanol, hexanoic acid, and hexanol.

4. A method for a microorganism to produce a metabolite, characterized in that, It includes the step of using the carbon fixation system described in claim 1 or the composition described in claim 2; More preferably, the metabolite is a primary metabolite or a secondary metabolite of the microorganism; More preferably, the metabolite includes one or more of acetic acid, ethanol, butyric acid, butanol, hexanoic acid, and hexanol.

5. A method for improving the H2 utilization efficiency of microorganisms, characterized in that, Including the step of adding a hydrogenase-mimicking catalyst during the production or fermentation process of the microorganism, for example, before inoculation of fermentation culture or at a certain stage after inoculation; the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst comprises a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacterium is a bacterium that fixes CO2 through the Wood-Ljungdahl pathway and grows autotrophically; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gas as the main gas sources; further preferably, the gas source composition is H2, CO2 or H2, CO2 and CO or H2, CO; further preferably, the proportion of H2 is 10% to 90%.

6. A method for promoting microbial carbon fixation, characterized in that, A step of adding a hydrogenase-mimicking catalyst during the production or fermentation process of the microorganism, for example, before inoculation of fermentation culture or at a certain stage after inoculation; the hydrogenase-mimicking catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase-mimicking catalyst comprises a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase-mimicking catalyst is selected from one or more of platinum-magnetite hydrogenase-mimicking catalyst, cobalt-carbon nanotube hydrogenase-mimicking catalyst, nickel-carbon nanotube hydrogenase-mimicking catalyst, iron-carbon nanotube hydrogenase-mimicking catalyst, iron-silica hydrogenase-mimicking catalyst, nickel-silica hydrogenase-mimicking catalyst and cobalt-silica hydrogenase-mimicking catalyst; further preferably, the acetic acid-producing bacterium is a bacterium that fixes CO2 through the Wood-Ljungdahl pathway and grows autotrophically; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gas as the main gas sources; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is H2, CO; further preferably, the proportion of H2 is 10% to 90%.

7. A method for promoting or improving the carbon fixation efficiency of microorganisms, characterized in that, A step of adding a hydrogenase mimic catalyst during the production or fermentation process of the microorganism, for example, before inoculation of fermentation culture or at a certain stage after inoculation; the hydrogenase mimic catalyst is a heterogeneous catalyst with hydrogen activation ability designed by mimicking the function of hydrogenase; further preferably, the hydrogenase mimic catalyst comprises a carrier and an active center; further preferably, the carrier is selected from one or more of carbon nanotubes, silica, graphene, graphene oxide, carbon dots or magnetite; further preferably, the active center is selected from one or more of iron, cobalt, nickel, palladium and platinum; further preferably, the hydrogenase mimic catalyst is selected from one or more of platinum-magnetite hydrogenase mimic catalyst, cobalt-carbon nanotube hydrogenase mimic catalyst, nickel-carbon nanotube hydrogenase mimic catalyst, iron-carbon nanotube hydrogenase mimic catalyst, iron-silica hydrogenase mimic catalyst, nickel-silica hydrogenase mimic catalyst and cobalt-silica hydrogenase mimic catalyst; further preferably, the acetic acid-producing bacterium is a bacterium that fixes CO2 through the Wood-Ljungdahl pathway and grows autotrophically; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium ragsdalei and Clostridium carboxidivorans; further preferably, the acetic acid-producing bacterium is selected from one or more of Clostridium ljungdahlii DSM 13528, Clostridium autoethanogenum DSM 10061 or Clostridium carboxidivorans P7 DSM15243T; further preferably, the production or fermentation process uses H2 and C1 gases as the main gas sources; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is further H2, CO; further preferably, the proportion of H2 is 10% to 90%.

8. A method for producing ethanol by microorganisms, characterized in that, A step of utilizing the carbon fixation system according to claim 1 or the composition according to claim 2; further preferably, it includes a process of fermentation in an environment containing H2 and C1 gases; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is further H2, CO; further preferably, the proportion of H2 is 10% to 90%; further preferably, it includes the stages of strain activation, adaptive subculture and fermentation culture, and a step of adding the hydrogenase mimic catalyst during the fermentation culture stage.

9. A method for producing acetic acid by a microorganism, characterized in that, A step of utilizing the carbon fixation system according to claim 1 or the composition according to claim 2; further preferably, it includes a process of fermentation in an environment containing H2 and C1 gases; further preferably, the gas source composition is H2, CO2 or the composition is H2, CO2 and CO or the composition is further H2, CO; further preferably, the proportion of H2 is 10% to 90%; further preferably, it includes the stages of strain activation, adaptive subculture and fermentation culture, and a step of adding the hydrogenase mimic catalyst during the fermentation culture stage.

Images