Method and system for electric fermentation synthesis of hydrogen oxidizing bacteria single-cell protein for resisting active oxygen inhibition

Abstract

The invention discloses a method and a system for electric fermentation synthesis of hydrogen oxidizing bacteria single-cell protein with resistance to active oxygen inhibition, and belongs to the technical field of microbial fermentation. According to the system disclosed by the invention, generation and accumulation of active oxygen groups in the electrolysis process are effectively reduced through various technical means such as electrode surface modification, reasonable arrangement of electrode space, gradual increase of electrolysis current, optimization of culture medium components and the like; the technical problem that the synthesis efficiency of single-cell protein is low due to generation of active oxygen groups in an existing method is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial fermentation, and particularly relates to a method and system for electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition. Background Art

[0002] Single-cell protein (SCP) refers to the bacterial cell protein obtained by culturing single-cell microorganisms. Due to its high protein content and relatively complete amino acid composition, it has broad application prospects in the fields of feed, food, etc. Hydrogen-oxidizing bacteria (HOB) can use hydrogen and carbon dioxide for chemoautotrophic growth to synthesize SCP. It has a fast reproduction rate, is easy to culture, and has a high protein production efficiency, and has received great attention in recent years. The electro-fermentation technology that in-situ couples electrolyzed water and gas fermentation provides a new idea for the production of HOB-SCP, and has broad application prospects in the storage of renewable electric energy and the resource utilization of CO2.

[0003] The in-situ coupling of electrolyzed water and gas fermentation realizes the in-situ supply of hydrogen and oxygen, that is, the anode and cathode are directly inserted into the fermentation tank to electrolyze water in-situ to supply hydrogen and oxygen. This not only avoids the storage and transportation of gas, simplifies the structure of the system, but also improves the safety of the system, showing good application prospects. However, in this simple single-chamber electro-fermentation reactor, under high current density conditions, a large amount of reactive oxygen species (ROS), such as superoxide anion (O2 - -), hydrogen peroxide (H2O2), hydroxyl radical (OH), etc., will be generated during the electrolysis process. These ROS have a significant inhibitory effect on the growth and metabolism of hydrogen-oxidizing bacteria, seriously restricting the production efficiency of electro-fermentation synthesis of single-cell protein.

[0004] Regarding the problem of the inhibition of hydrogen-oxidizing bacteria by ROS generated during the electrolysis process, there have been some solutions. For example, by introducing antioxidants, such as superoxide dismutase, glutathione, vitamin C, etc., during the electrolysis process to help scavenge ROS; or by genetically engineering hydrogen-oxidizing bacteria to make them more tolerant to ROS. Although the existing technologies have solved the inhibitory effect of ROS on microorganisms to a certain extent, generally speaking, they still have not been able to effectively overcome the negative impact of high-concentration ROS on the growth of microorganisms during the electrolysis process, and lack a systematic and comprehensive solution. Therefore, how to reduce or eliminate the inhibitory effect of ROS on microorganisms such as hydrogen-oxidizing bacteria and improve the production efficiency of single-cell protein is still an urgent technical problem in this field. Summary of the Invention

[0005] The object of the present invention is to provide a method and system for electro-fermentative synthesis of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition, so as to solve the technical problem that the existing methods have low single-cell protein synthesis efficiency due to the generation of reactive oxygen species groups.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention discloses a system for electro-fermentative synthesis of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition, including an electro-fermentation reactor, electrode terminals, a dissolved oxygen electrode, a DC power supply, a CO2 inlet pipe, and an electrolyzed water component; the electrodes are arranged in the electro-fermentation reactor and are connected to the DC power supply outside the electro-fermentation reactor through the electrode terminals; the CO2 inlet pipe and the dissolved oxygen electrode are respectively inserted into the electro-fermentation reactor from the outside;

[0008] The electrolyzed water component consists of two identical composite stainless steel mesh electrodes and an ion exchange membrane; the composite stainless steel mesh electrode includes an outer electrode layer loaded with a nano-catalytic material on two layers and a substrate electrode layer loaded with CoP sandwiched in the middle; the electrolyzed water component is connected to the external DC power supply.

[0009] Further, an ion exchange membrane is arranged in the middle of the two composite stainless steel mesh electrodes to form an anode and a cathode; the distance between the cathode and the anode is 10 - 15 mm.

[0010] Further, the substrate electrode layer loaded with CoP is formed by synthesizing CoP nanowires on the surface of a stainless steel mesh by a hydrothermal method; the substrate electrode layer loaded with the nano-catalytic material is formed by loading the nano-catalytic material on the surface of the stainless steel mesh; the nano-catalytic material is MnO2 nanoparticles or Fe3O4 nanoparticles.

[0011] Further, the distance between the substrate electrode layer loaded with CoP and the substrate electrode layer loaded with the nano-catalytic material is 3 - 5 mm.

[0012] Further, an electrolyte without chloride ions is used in the electro-fermentation reactor; the components of the electrolyte include: KH2PO4 2.3 g / L; Na2HPO4·2H2O 2.9 g / L; NH4SO4 5 g / L; MgSO4·7H2O 0.5 g / L; CaSO4 0.01 g / L; MnSO4 0.005 g / L; NaVO3·H2O 0.005 g / L; Ferric sodium EDTA 0.10 g / L; NaHCO3 0.5 g / L; trace element solution 5 mL / L, vitamin solution 5 mL / L.

[0013] Further, the components of the trace element solution include: 0.10 g / L of ZnSO4·7H2O; 0.03 g / L of MnCl2·4H2O; 0.30 g / L of H3BO3; 0.20 g / L of CoSO4; 0.01 g / L of CuSO4; 0.02 g / L of Ni2SO4; 0.03 g / L of Na2MoO4·2H2O.

[0014] Further, the components of the vitamin solution include: 0.1 g / L of riboflavin; 0.5 g / L of thiamine hydrochloride; 0.5 g / L of nicotinic acid; 0.5 g / L of pyridoxine hydrochloride; 0.5 g / L of calcium pantothenate; 0.001 g / L of biotin; 0.002 g / L of folic acid; 0.01 g / L of vitamin B12.

[0015] The present invention also discloses a method for electro-fermenting and synthesizing hydrogen-oxidizing bacteria single-cell protein for anti-reactive oxygen species inhibition by the above system, comprising the following steps: First, add an electrolyte solution inside the electro-fermentation reactor; then apply a current to the water electrolysis component through a DC power supply to in-situ generate H2 and O2 inside the electro-fermentation reactor, and at the same time input CO2 into the electro-fermentation reactor through a CO2 inlet pipe, and control the volume ratio of the flow rate of CO2 to the electrolytically generated H2 to be 1:7; then add hydrogen-oxidizing bacteria into the electro-fermentation reactor for mixed fermentation, control the temperature during the mixed fermentation process to be 25-30 °C, and control the pH value to be 6.7-7.1; continuously monitor the biomass inside the electro-fermentation reactor through absorbance, and when the absorbance no longer increases, end the experiment to obtain single-cell protein.

[0016] Further, it comprises the following steps: First, add an electrolyte solution inside the electro-fermentation reactor; then apply a current to the water electrolysis component through a DC power supply to in-situ generate H2 and O2 inside the electro-fermentation reactor, and at the same time input CO2 into the electro-fermentation reactor through a CO2 inlet pipe, and control the volume ratio of the flow rate of CO2 to the electrolytically generated H2 to be 1:7; then add hydrogen-oxidizing bacteria into the electro-fermentation reactor for mixed fermentation, control the temperature during the mixed fermentation process to be 25-30 °C, and control the pH value to be 6.7-7.1; continuously monitor the biomass inside the electro-fermentation reactor through absorbance, and when the absorbance no longer increases, end the experiment to obtain single-cell protein.

[0017] Further, the hydrogen-oxidizing bacteria include Rhodococcus, Flavobacterium, Flexibacter, Hydrogenophaga or a mixture of several of them.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention discloses an electro-fermentation synthesis system of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition. By providing a composite stainless steel mesh electrode composed of a substrate electrode layer loaded with CoP and a substrate electrode layer loaded with a nano-catalytic material, it not only has good electrocatalytic activity for hydrogen evolution and oxygen evolution, but also greatly reduces the generation of reactive oxygen species groups at the cathode and anode. At the same time, the substrate electrode layer loaded with the nano-catalytic material has the ability to catalytically decompose reactive oxygen species groups, further reducing the diffusion of the reactive oxygen species groups generated by electrolysis into the electrolyte, and solving the technical problem that the existing methods have low single-cell protein synthesis efficiency due to the generation of reactive oxygen species groups.

[0020] Furthermore, the electrode of this system uses stainless steel mesh as the substrate electrode material, and CoP nanowires are synthesized on the stainless steel surface by the hydrothermal method. It not only has good electrocatalytic activity for hydrogen evolution and oxygen evolution, but also greatly reduces the generation of reactive oxygen species groups at the cathode and anode; 1 - 4 layers of stainless steel meshes loaded with manganese dioxide or iron tetroxide nanoparticles are added on the stainless steel electrode surface. The manganese dioxide or iron tetroxide nanoparticles have the ability to catalytically decompose reactive oxygen species groups, further reducing the diffusion of the reactive oxygen species groups generated by electrolysis into the electrolyte.

[0021] Furthermore, an ion exchange membrane is used for isolation between the positive and negative electrodes to prevent the substances generated at the two electrodes from mixing and interfering with each other, and to avoid the direct diffusion of the oxygen generated by the anode electrolysis to the cathode, and then the reduction to generate reactive oxygen species groups at the cathode.

[0022] The present invention also discloses a method for electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition using the above system. This method gradually increases the current density of electrolysis according to the biomass of hydrogen-oxidizing bacteria, and at the same time strictly detects and controls the dissolved oxygen concentration in the reactor using a dissolved oxygen electrode or redox potential, so as to limit the concentration of reactive oxygen species groups, thereby reducing the growth inhibition of hydrogen-oxidizing bacteria; the electrolyte used replaces hydrochloride with sulfate, strictly controls the concentration of chloride ions, and avoids the generation of chlorine-containing fungicides by anode electrolysis. A complex of ferrous ions is used to replace free ferrous ions to avoid the generation of hydroxyl radicals (·OH) by ferrous ions catalyzing hydrogen peroxide (H2O2). Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the electro-fermentation synthesis system of hydrogen-oxidizing bacteria single-cell protein with resistance to reactive oxygen species inhibition of the present invention;

[0024] Figure 2 It is a graph showing the change of the growth of hydrogen-oxidizing bacteria over time under a constant current condition of 3A using a common stainless steel electrode and the system of the present invention;

[0025] Figure 3Graph showing the growth of hydrogen-oxidizing bacteria over time under constant current and increasing current gradient conditions using the system of the present invention;

[0026] Wherein: 1 - Substrate electrode layer loaded with CoP; 2 - Substrate electrode layer loaded with nano-catalytic material; 3 - Ion exchange membrane; 4 - Electrode terminal; 5 - Dissolved oxygen electrode; 6 - DC power supply; 7 - CO2 inlet pipe; 8 - Electrolyzed water component; 9 - Electro-fermentation reactor. Detailed implementation manners

[0027] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall in no way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have covered and specifically disclosed all possible sub-ranges and individual values within the range (including integers and fractions).

[0030] In this article, unless otherwise specified, terms such as "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0031] In this article, for the sake of simplicity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered to be within the scope described in this specification.

[0032] The present invention provides an electro-fermentation synthesis system for hydrogen-oxidizing bacteria single-cell protein resistant to reactive oxygen species inhibition, including an electro-fermentation reactor 9, in which an innovative composite stainless steel mesh electrode is arranged; the composite stainless steel mesh electrode includes a substrate electrode layer 1 loaded with CoP and a substrate electrode layer 2 loaded with a nano-catalytic material. The substrate electrode layer 1 loaded with CoP is an electrode material generated by using anti-reactive oxygen species groups, and the substrate electrode layer 2 loaded with the nano-catalytic material is a catalytic material that can catalyze the decomposition of reactive oxygen species groups; the catalytic materials that can catalyze the decomposition of reactive oxygen species groups are interspersed, and the outermost layers on both sides of the electrode are the substrate electrode layer 2 loaded with the nano-catalytic material; the anode and cathode of the electrode are separated by an ion exchange membrane 3 to prevent the oxygen generated at the anode from diffusing to the cathode and being reduced to generate reactive oxygen species; the system also includes electrode terminals 4, a dissolved oxygen electrode 5, a DC power supply 6, a CO2 inlet pipe 7, and an electrolyzed water component 8; the electro-fermentation reactor 9 is connected to the DC power supply 6 outside the electro-fermentation reactor 9 through the electrode terminals 4; the CO2 inlet pipe 7 and the dissolved oxygen electrode 5 are respectively inserted into the electro-fermentation reactor 9 from the outside; the electrolyzed water component 8 is connected to the DC power supply 6.

[0033] Preferably, the substrate electrode layer 1 loaded with CoP is formed by synthesizing CoP nanowires on the surface of a stainless steel mesh using a hydrothermal method; the substrate electrode layer 2 loaded with the nano-catalytic material is formed by loading the nano-catalytic material on the surface of the stainless steel mesh; the nano-catalytic material is MnO2 nanoparticles or Fe3O4 nanoparticles.

[0034] Preferably, two layers of stainless steel meshes (substrate electrode layer 2 loaded with the nano-catalytic material) modified with MnO2 or Fe3O4 are arranged on both sides of the electrode, and the distance between the stainless steel meshes is 3-5 mm.

[0035] Preferably, the distance between the anode and the cathode is 10-15 mm.

[0036] An innovative electrolyte is also arranged in the electro-fermentation reactor 9. The electrolyte uses sulfate to replace chloric acid and complex ferrous ions to replace free ferrous ions, avoiding the generation of chlorine-containing active groups and Fenton reactions; the components of the electrolyte include: KH2PO4 2.3 g / L; Na2HPO4·2H2O 2.9 g / L; NH4SO4 5 g / L; MgSO4·7H2O 0.5 g / L; CaSO4 0.01 g / L; MnSO4 0.005 g / L; NaVO3·H2O 0.005 g / L; Ferric sodium EDTA 0.10 g / L; NaHCO3 0.5 g / L; trace element solution 5 mL / L, vitamin solution 5 mL / L.

[0037] Preferably, the composition of the trace element solution includes: 0.10 g / L of ZnSO4·7H2O; 0.03 g / L of MnCl2·4H2O; 0.30 g / L of H3BO3; 0.20 g / L of CoSO4; 0.01 g / L of CuSO4; 0.02 g / L of Ni2SO4; 0.03 g / L of Na2MoO4·2H2O.

[0038] Preferably, the composition of the vitamin solution includes: 0.1 g / L of riboflavin; 0.5 g / L of thiamine hydrochloride; 0.5 g / L of nicotinic acid; 0.5 g / L of pyridoxine hydrochloride; 0.5 g / L of calcium pantothenate; 0.001 g / L of biotin; 0.002 g / L of folic acid; 0.01 g / L of vitamin B12.

[0039] The present invention also discloses a method for electro-fermentation synthesis of hydrogen-oxidizing bacterial single-cell protein using the above system, which includes the following steps: First, add an electrolyte solution inside the electro-fermentation reactor 9; then apply a current to the water electrolysis assembly 8 through the DC power supply 6 to in-situ generate H2 and O2 inside the electro-fermentation reactor 9. At the same time, input CO2 into the electro-fermentation reactor 9 through the CO2 inlet pipe 7, and control the flow rate of CO2 through an external mass flow controller, so that the volume ratio of the flow rate of CO2 to the electrolytically generated H2 is 1:7; then add hydrogen-oxidizing bacteria into the electro-fermentation reactor 9 for mixed fermentation. The temperature during the fermentation process is controlled at 25-30 °C, and the pH value is maintained between 6.7 and 7.1 by adding acid and base; continuously monitor the biomass inside the electro-fermentation reactor 9 through absorbance. When the absorbance no longer increases, end the experiment and centrifuge to obtain the hydrogen-oxidizing bacterial single-cell protein.

[0040] Preferably, for a reactor with 1 L of electrolyte solution, the initial electrolysis current is 50 mA, and the current increase mode is 50-100-200-400-800-1600-3200-6400 mA. After each increase in current, when the gas outlet rate of the reactor is less than 5 mL / min and the dissolved oxygen concentration is lower than 1 mg / min, then increase to the next current.

[0041] Preferably, the hydrogen-oxidizing bacteria include Rhodobacter, Flavobacterium, Flexibacter, or Hydrogenophaga, the culture temperature of the reactor is 30 °C, and the pH is 7.0.

[0042] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0043] In the following examples, conventional instruments and equipment in the art are used. For the experimental methods without specific conditions noted in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. In the following examples, various raw materials are used. Unless otherwise specified, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0044] Example 1

[0045] A method for electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein with anti-reactive oxygen species inhibition, comprising the following steps:

[0046] First, take two 1L electro-fermentation reactors 9 and respectively install a common stainless steel mesh electrode (control group) and the developed composite stainless steel mesh electrode (experimental group); the stainless steel mesh used in the experiment has an area of 10 cm * 15 cm, a material of 316L, and a pore size of 40 mesh; the common stainless steel mesh electrode is composed of three layers of stainless steel mesh, and the composite stainless steel mesh electrode of the experimental group includes one layer of CoP-modified stainless steel mesh 1 and two layers of MnO2 nanoparticle-modified stainless steel mesh 2, and the distance between the three layers of stainless steel mesh is 5 mm; the anode and cathode use the same electrode, and the anode and cathode are separated by a cation exchange membrane 3, and the central distance between the cathode and anode is 15 mm; put 700 mL of electrolyte into the electro-fermentation reactor 9, the composition of the electrolyte is as shown above, connect a DC power supply 6, apply a current of 3 A, and after electrolyzing for 30 min, measure the content of reactive oxygen species groups in the reactors of the control group and the experimental group respectively; as shown in Table 1, it can be seen that the composite stainless steel electrode reported in the present invention can reduce the generation amount of reactive oxygen species groups by more than 90%.

[0047] Table 1 Comparison table of the content of reactive oxygen species groups in the reactor after electrolyzing for 30 min under 3 A conditions using a common stainless steel electrode and the system of the present invention

[0048]

[0049] Example 2

[0050] According to the reactor and operating conditions of Example 1, the CO2 inlet rate is controlled at 3.5 mL / min, the pH value of the electrolyte is controlled between 6.7 - 7.1, and the temperature is controlled at 28 ± 2 °C; inoculate the HOB functional flora mainly composed of Flexibacter into the electro-fermentation reactor 9, and set the initial OD600 to about 1; sample and measure OD600 every 24 h to characterize the growth of HOB; as Figure 2As shown, when using ordinary stainless steel electrodes, HOB grows slowly, and the maximum OD600 value is only 6.3; when using the composite stainless steel electrode of the present invention, HOB enters an exponential growth stage after a 2-day lag period. On the sixth day of the reactor operation, the OD600 value reaches 46, the corresponding cell dry weight content reaches 20 g / L, and the protein content of single cell protein reaches 65%; it can be seen that the use of the composite stainless steel electrode reported in the present invention can greatly improve the growth rate of HOB in the electric fermentation system.

[0051] Example 3

[0052] The operating conditions of Example 2 were followed, but the current application mode and CO2 supply of the reactor were changed; the initial current of the reactor was set to 200 mA, and the CO2 flow rate was set to 0.24 mL / min; the current increase mode was 200-400-800-1600-3200-6400 mA, and the CO2 flow rate was increased proportionally each time the current was increased. When the reactor gas outlet rate was less than 3 mL / min, the current and CO2 flow rate were increased to the next level; Figure 3 As shown in the figure, compared with the constant current mode, the operation mode of gradually increasing the current can not only shorten the growth lag period of HOB, but also further increase the maximum bacterial concentration of HOB; using the operation mode of gradually increasing the current, HOB has almost no lag period after inoculation, directly enters the rapid growth stage, and almost reaches the maximum bacterial concentration on the 4th day of fermentation; under the operating conditions, the maximum OD600 value of the reactor can reach 52, the maximum cell dry weight can reach 25g / L, and the protein content of single cell protein can reach 67%; it can be seen that the operation mode of gradually increasing the current can reduce the inhibition of HOB growth startup by free radicals generated in the direct high current mode.

[0053] In summary, by adopting the composite stainless steel electrode and electrode arrangement of the present invention, the generation of ROS and the diffusion to the electrolyte during the electrolysis of water under high current density conditions can be effectively reduced, thereby greatly improving the survival and growth state of strong oxidizing bacteria in the electric fermentation system. At the same time, the operation mode of increasing the current in a gradient also greatly improves the adaptability of hydrogen oxidizing bacteria to electrolysis. In short, the anti-ROS scheme proposed in the present invention is a fundamental, systematic and economical scheme, which avoids the addition of antioxidants in the process of synthesizing hydrogen oxidizing bacteria single cells by electrofermentation, greatly reduces the production cost, and also enables more non-genetically engineered hydrogen oxidizing bacteria with low tolerance to ROS to be used, enriching the types of hydrogen oxidizing bacteria single cells synthesized by electrofermentation.

[0054] The above contents are only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein system for resisting reactive oxygen species inhibition, characterized in that, It includes an electro-fermentation reactor (9), electrode terminals (4), a dissolved oxygen electrode (5), a DC power supply (6), a CO2 inlet pipe (7), and an electrolyzed water assembly (8); the electrodes are arranged in the electro-fermentation reactor (9) and are connected to the DC power supply (6) outside the electro-fermentation reactor (9) through the electrode terminals (4); the CO2 inlet pipe (7) and the dissolved oxygen electrode (5) are respectively inserted into the electro-fermentation reactor (9) from the outside; The electrolyzed water assembly (8) is composed of two identical composite stainless steel mesh electrodes and an ion exchange membrane (3); the composite stainless steel mesh electrode includes an outer electrode layer (2) loaded with a nano-catalytic material and a substrate electrode layer (1) loaded with CoP sandwiched in the middle; the electrolyzed water assembly (8) is connected to the external DC power supply (6).

2. The electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein system for anti-reactive oxygen species inhibition according to claim 1, characterized in that, An ion exchange membrane (3) is arranged in the middle of the two composite stainless steel mesh electrodes to form an anode and a cathode; the distance between the cathode and the anode is 10 - 15 mm.

3. An electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein system for anti-reactive oxygen species inhibition according to claim 1, characterized in that, The substrate electrode layer (1) loaded with CoP is formed by synthesizing CoP nanowires on the surface of a stainless steel mesh by a hydrothermal method; the substrate electrode layer (2) loaded with the nano-catalytic material is formed by loading the nano-catalytic material on the surface of the stainless steel mesh; the nano-catalytic material is MnO2 nanoparticles or Fe3O4 nanoparticles.

4. An electro-fermentation synthesis of hydrogen-oxidizing bacteria single cell protein system for anti-reactive oxygen species inhibition according to claim 1, characterized in that, The distance between the substrate electrode layer (1) loaded with CoP and the substrate electrode layer (2) loaded with the nano-catalytic material is 3 - 5 mm.

5. An electro-fermentation synthetic hydrogen-oxidizing bacterial single-cell protein system for anti-reactive oxygen species inhibition, characterized in that, An electrolyte without chloride ions is used in the electro-fermentation reactor (9); the components of the electrolyte include: KH2PO4 2.3 g / L; Na2HPO4·2H2O 2.9 g / L; NH4SO4 5 g / L; MgSO4·7H2O 0.5 g / L; CaSO4 0.01 g / L; MnSO4 0.005 g / L; NaVO3·H2O 0.005 g / L; Ferric sodium EDTA 0.10 g / L; NaHCO3 0.5 g / L; trace element solution 5 mL / L, vitamin solution 5 mL / L.

6. The electro-fermentation synthesis of hydrogen-oxidizing bacteria single-cell protein system for anti-reactive oxygen species inhibition according to claim 5, characterized in that The components of the trace element solution include: ZnSO4·7H2O 0.10 g / L; MnCl2·4H2O 0.03 g / L; H3BO3 0.30 g / L; CoSO4 0.20 g / L; CuSO4 0.01 g / L; Ni2SO4 0.02 g / L; Na2MoO4·2H2O 0.03 g / L.

7. An electro-fermentation synthetic hydrogen-oxidizing bacterial single-cell protein system for anti-reactive oxygen species inhibition, characterized in that, The components of the vitamin solution include: riboflavin 0.1 g / L; thiamine hydrochloride 0.5 g / L; nicotinic acid 0.5 g / L; pyridoxine hydrochloride 0.5 g / L; calcium pantothenate 0.5 g / L; biotin 0.001 g / L; folic acid 0.002 g / L; vitamin B12 0.01 g / L.

8. A method for electro-fermentative synthesis of hydrogen-oxidizing bacterial single-cell protein with resistance to reactive oxygen species inhibition, characterized in that, It is carried out by using the system described in claims 1 to 7, including the following steps: First, add electrolyte inside the electro-fermentation reactor (9); then apply a current to the water electrolysis component (8) through the DC power supply (6) to in-situ generate H2 and O2 in the electro-fermentation reactor (9), and at the same time input CO2 into the electro-fermentation reactor (9) through the CO2 inlet pipe (7), and control the volume ratio of the flow rate of CO2 to the electrolytically generated H2 to be 1:7; then add hydrogen-oxidizing bacteria to the electro-fermentation reactor (9) for mixed fermentation, and control the temperature during the mixed fermentation process to be 25-30 °C and the pH value to be 6.7-7.1; continuously monitor the biomass in the electro-fermentation reactor (9) by absorbance, and end the experiment to obtain single-cell protein when the absorbance no longer increases.

9. A method for electro-fermenting and synthesizing hydrogen-oxidizing bacteria single-cell protein with anti-reactive oxygen species inhibition, characterized in that, The initial current of the electrolysis for applying the current is 50 mA, and the increasing mode of the current is 50-100-200-400-800-1600-3200-6400 mA. After each increase in the current, when the gas outlet rate of the reactor is less than 5 mL / min and the dissolved oxygen concentration is lower than 1 mg / min, then increase it to the next current. The flow rate of the CO2 is controlled by an external mass flow controller; the pH value is controlled by adding acid or base.

10. A single-cell protein of electro-fermentative synthesized hydrogen-oxidizing bacteria with anti-reactive oxygen species inhibition according to claim 8, characterized in that, The hydrogen-oxidizing bacteria include Rhodococcus, Flavobacterium, Flexibacter, Hydrogenophaga or a mixture of several of them.

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