A novel Paenibacillus sp. GD-2 and its application in carbon fixation

Abstract

The present invention relates to the technical field of microbial carbon fixation, in particular to a novel Paenibacillus sp. GD-2 and its application in carbon fixation. The preservation number of the Paenibacillus sp. GD-2 of the present invention is CGMCC No. 31835. The Paenibacillus sp. GD-2 provided by the present invention is a potential new species in the genus Paenibacillus isolated from the soil between the fixed plates in a salinized photovoltaic field area. It has dual carbon fixation capabilities, can convert carbon dioxide in the atmosphere into carbonate minerals, and grow by converting carbon dioxide into its own biological carbon (organic carbon). It can grow under the condition of only containing atmospheric carbon dioxide, and can significantly improve its growth rate by using NaHCO3. It does not require additional carbon sources and electron donors, reducing the carbon fixation cost, which is of great significance for enhancing the potential of soil carbon sequestration and sink, promoting the high-quality development of the photovoltaic industry in salinized vulnerable areas, and alleviating global warming.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial carbon fixation, and particularly relates to a novel Paenibacillus sp. GD-2 and its application in carbon fixation. Background Art

[0002] Existing studies have shown that functional microorganisms such as nitrogen-fixing bacteria and cellulose-degrading bacteria play an important role in improving saline-alkali land, restoring soil physical and chemical properties, and ecological environment. Improving the potential of soil carbon sequestration and sink enhancement is an urgent need to restore the ecological function of saline-alkali land and mitigate climate change. However, there is still a lack of research on the isolation and screening of soil carbon-fixing microorganisms and their carbon-fixing abilities, and there is even more lack of relevant research on the precise identification and screening of soil carbon-fixing microorganisms in the photovoltaic field of saline-alkali land. Therefore, isolating and screening efficient carbon-fixing native functional microorganisms in the photovoltaic field of saline-alkali land has important potential application value for stimulating and enhancing the synergistic benefits of native microorganisms in improving soil and carbon sequestration and sink enhancement. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a novel Paenibacillus sp. GD-2 and its application in carbon fixation. The Paenibacillus sp. GD-2 provided by the present invention has dual carbon-fixing abilities, can convert carbon dioxide in the atmosphere into carbonate minerals, and grow by using carbon dioxide to convert into its own biological carbon (organic carbon), which is of great significance for enhancing the potential of soil carbon sequestration and sink, promoting the high-quality development of the photovoltaic industry in saline-alkali vulnerable areas, and alleviating global warming.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a Paenibacillus sp. GD-2 with a preservation number of CGMCC No. 31835.

[0006] The present invention provides a carbon-fixing microbial inoculum, comprising the Paenibacillus sp. GD-2 described in the above technical solution.

[0007] Preferably, the OD value of Paenibacillus sp. GD-2 in the carbon-fixing microbial inoculum 600 ≥0.6.

[0008] The present invention provides a preparation method of the carbon-fixing microbial inoculum described in the above technical solution, comprising the following steps:

[0009] Inoculate the Paenibacillus sp. GD-2 described in the above technical solution into a culture medium for cultivation to obtain the carbon-fixing microbial inoculum; the culture medium comprises a culture medium without an organic carbon source.

[0010] Preferably, the medium without organic carbon source comprises components in the following concentrations: 0.5 g / L of Na2HPO4, 0.5 g / L of KH2PO4, 0.3 g / L of MgSO4, 0.2 g / L of CaCl2, 0.5 g / L of NH4Cl, 0.25 g / L of NaNO3, 0.4 g / L of NaCl, and 10 mL / L of trace element solution; the trace element solution comprises components in the following concentrations: 0.3 g / L of FeCl2, 0.3 g / L of FeSO4·7H2O, 0.15 g / L of MnSO4·H2O, 0.25 g / L of ZnSO4·7H2O, 0.2 g / L of CoCl2; the pH value of the medium without organic carbon source is 7.0 - 7.4.

[0011] Preferably, the medium without organic carbon source further comprises an inorganic carbon source; the inorganic carbon source comprises sodium bicarbonate and / or sodium carbonate.

[0012] Preferably, the culturing time is 5 - 7 days; the culturing temperature is 28°C.

[0013] The present invention provides the application of Paenibacillus sp. GD-2 described in the above technical solution, or the carbon fixation microbial inoculant described in the above technical solution, or the carbon fixation microbial inoculant prepared by using the preparation method described in the above technical solution in carbon fixation, and the carbon source for carbon fixation comprises an inorganic carbon source.

[0014] Preferably, the inorganic carbon source comprises one or more of carbon dioxide, sodium bicarbonate, and sodium carbonate.

[0015] Preferably, the carbon fixation includes: inducing the inorganic carbon source to generate carbon-containing minerals and / or converting the inorganic carbon source into its own biological carbon.

[0016] Beneficial effects:

[0017] The present invention provides a strain of Paenibacillus sp. GD-2 with the preservation number of CGMCC No. 31835. The Paenibacillus sp. GD-2 provided by the present invention is a potential new species in the genus Paenibacillus isolated from the soil between the fixed plates in the salinized photovoltaic field area. It has dual carbon fixation ability, can convert carbon dioxide in the atmosphere into carbonate minerals, and grow by converting carbon dioxide into its own biological carbon (organic carbon). It can grow under the condition of only containing atmospheric carbon dioxide, and at the same time can significantly improve its growth rate by using NaHCO3. It does not require an external carbon source and electron donor, reducing the carbon fixation cost, and is of great significance for enhancing the potential of soil carbon fixation and carbon sequestration, promoting the high-quality development of the photovoltaic industry in the fragile salinized area, and alleviating global warming. Description of the drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required for use in the embodiments will be briefly introduced below.

[0019] Figure 1 It is the cell morphology diagram of Paenibacillus sp. GD-2;

[0020] Figure 2 It is the colony characteristic diagram of Paenibacillus sp. GD-2;

[0021] Figure 3 It is the phylogenetic tree of the 16S rRNA gene of Paenibacillus sp. GD-2;

[0022] Figure 4 It is the determination result of the RubisCO enzyme activity of Paenibacillus sp. GD-2;

[0023] Figure 5 It is the determination result of the carbon fixation ability of Paenibacillus sp. GD-2 under different conditions;

[0024] Figure 6 It is the carbon fixation pathway of Paenibacillus sp. GD-2; wherein, the letters represent the key enzymes in the carbon fixation pathway, pps - phosphoenolpyruvate carboxylase; ppc - phosphoenolpyruvate carboxylase; aspC - aspartate aminotransferase; ItaE - threonine aldolase; glyA - glycine hydroxymethyltransferase; SDS - serine dehydrogenase;

[0025] Figure 7 It is the electron microscopy scan and elemental distribution map of the carbon-containing minerals induced by Paenibacillus sp. GD-2 in urea broth medium;

[0026] Among them, * represents p < 0.05, *** represents p < 0.001, and **** represents p < 0.0001.

[0027] Biological preservation description

[0028] Paenibacillus sp. GD-2, classified and named as Paenibacillus sp., was deposited in the China General Microbiological Culture Collection Center (CGMCC) on September 3, 2024. The deposit address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 31835. Detailed implementation manners

[0029] The present invention provides a strain of Paenibacillus sp. GD-2 with a deposit number of CGMCC No. 31835.

[0030] Bacillus sp. GD-2 provided by the present invention is a potential new species in the genus Bacillus isolated from the soil between fixed plates in a salinized photovoltaic field. The single colony is round, light yellow and viscous, with a moist, smooth, opaque surface and regular edges. It has a dual carbon fixation ability, can convert carbon dioxide in the atmosphere or inorganic carbon in the medium into carbonate minerals (including but not limited to calcium carbonate and its polymorphs), and grow by converting carbon dioxide into its own biological carbon (organic carbon). It can grow under the condition of only containing atmospheric carbon dioxide, and can significantly improve its growth rate by using NaHCO3. It does not require an external carbon source and electron donor, reducing the carbon fixation cost, providing strain resources for enhancing the carbon fixation and emission reduction ability of salinized soil, providing technical support for in-depth understanding of the microbial regulation process of the occurrence form of nutrients in salinized soil, laying a foundation for proposing soil microbial improvement technologies in photovoltaic fields, and promoting the high-quality development of the photovoltaic industry in fragile salinized areas.

[0031] Based on the above advantages, the present invention provides a carbon-fixing microbial inoculant, which comprises Bacillus sp. GD-2 described in the above technical solution.

[0032] As an embodiment, the OD of Bacillus sp. GD-2 in the carbon-fixing microbial inoculant 600 value ≥ 0.6.

[0033] The present invention provides a preparation method of the carbon-fixing microbial inoculant described in the above technical solution, comprising the following steps:

[0034] Inoculate Bacillus sp. GD-2 described in the above technical solution into a medium for culture to obtain the carbon-fixing microbial inoculant; the medium comprises a medium without an organic carbon source.

[0035] As an embodiment, the medium without an organic carbon source comprises components with the following concentrations: Na2HPO4 0.5 g / L, KH2PO4 0.5 g / L, MgSO4 0.3 g / L, CaCl2 0.2 g / L, NH4Cl 0.5 g / L, NaNO3 0.25 g / L, NaCl 0.4 g / L, trace element solution 10 mL / L; the trace element solution comprises components with the following concentrations: FeCl2 0.3 g / L, FeSO4·7H2O 0.3 g / L, MnSO4·H2O 0.15 g / L, ZnSO4·7H2O 0.25 g / L, CoCl2 0.2 g / L; the pH value of the medium without an organic carbon source is 7.0 - 7.4.

[0036] As an implementation manner, the medium without organic carbon source further includes an inorganic carbon source; the inorganic carbon source includes sodium bicarbonate and / or sodium carbonate. By adding an inorganic carbon source, especially sodium bicarbonate, the growth rate of Paenibacillus sp. GD-2 can be significantly increased, thereby improving its carbon fixation ability.

[0037] As an implementation manner, the concentration of the inorganic carbon source in the medium without organic carbon source is 0.3 - 0.8 g / L. As another implementation manner, the concentration of the inorganic carbon source in the medium without organic carbon source is 0.5 - 0.63 g / L.

[0038] As an implementation manner, the culture time is 5 - 7 days; the culture temperature is 28 °C.

[0039] Based on the above advantages, the present invention provides the application of Paenibacillus sp. GD-2 described in the above technical solution, or the carbon fixation microbial agent described in the above technical solution, or the carbon fixation microbial agent prepared by using the preparation method described in the above technical solution in carbon fixation, and the carbon source for carbon fixation includes an inorganic carbon source. As an implementation manner, the inorganic carbon source includes one or more of carbon dioxide, sodium bicarbonate and sodium carbonate. As another implementation manner, the carbon dioxide is the carbon dioxide in the atmosphere. The Paenibacillus sp. GD-2 provided by the present invention can convert the carbon dioxide in the atmosphere or the inorganic carbon in the medium into carbonate minerals, and grow by using carbon dioxide to convert into its own biological carbon (organic carbon), thereby playing a dual carbon fixation role; the carbon-containing minerals include but are not limited to calcium carbonate and the polymorphs of calcium carbonate.

[0040] In order to further illustrate the present invention, the following will combine the drawings and embodiments to describe in detail a novel Paenibacillus sp. GD-2 provided by the present invention and its application in carbon fixation, but they cannot be understood as limiting the protection scope of the present invention.

[0041] Example 1 Isolation and Identification of Carbon Fixation Strain Paenibacillus sp. GD-2

[0042] Taking the soil between the fixed plates in the Daqing saline-alkali photovoltaic field area as the target soil, the specific screening scheme is as follows:

[0043] 1. Collect the soil at a depth of 0 - 20 cm, take 10.0 g of the collected soil, add it to 100 mL of sterilized water, place it on a shaker for shaking (180 revolutions per minute, shake for 30 min) to make a soil suspension. Then dilute the soil suspension by a factor of 10 in a gradient to 10 -4Multiply by this factor, take 0.2 mL of the soil dilution, spread it onto a solid medium without an organic carbon source, and culture it at 28 °C for 7 days. The formulation of the solid medium without an organic carbon source is as follows: 0.5 g / L of Na2HPO4, 0.5 g / L of KH2PO4, 0.3 g / L of MgSO4, 0.2 g / L of CaCl2, 0.5 g / L of NaHCO3, 0.5 g / L of NH4Cl, 0.25 g / L of NaNO3, 0.4 g / L of NaCl, 10 mL / L of a trace element solution, and 20 g / L of agar, with a pH value of 7.0; the formulation of the trace element solution is as follows: 0.3 g / L of FeCl2, 0.3 g / L of FeSO4·7H2O, 0.15 g / L of MnSO4·H2O, 0.25 g / L of ZnSO4·7H2O, and 0.2 g / L of CoCl2.

[0044] 2. Pick different colonies with good morphology, growth vigor, and relatively fast growth rate from the solid medium without an organic carbon source, and use the inoculation loop to perform streak plate method multiple times to purify them on a new solid medium without an organic carbon source until pure culture. Through the dilution plate method, 25 carbon-fixing bacteria were initially isolated and purified. Select colonies with good growth vigor for the secondary screening of carbon-fixing function (refer to Example 2), and pick the 1 strain with the best effect among them, denoted as GD-2. Use a scanning electron microscope to determine that the cell morphology of this strain is rod-shaped ( Figure 1 ), and the colonies it produces on the solid medium are small, round, light yellow and viscous, with a moist, smooth, opaque surface and regular edges ( Figure 2 ).

[0045] 3. Further perform 16S rRNA gene sequencing on this strain: Use the universal primers 27F (SEQ ID NO.1) and 1492R (SEQ ID NO.2) to perform PCR amplification on the genomic DNA of the strain, and then sequence the amplification product. The sequencing result is as shown in SEQ ID NO.3, specifically as follows:

[0046]

[0047] The primer sequences are as follows:

[0048] 27F (SEQ ID NO.1): 5'-AGTTTGATCMTGGCTCAG-3';

[0049] 1492R (SEQ ID NO.2): 5'-GGTTACCTTGTTACGACTT-3'.

[0050] Then, using the NCBI database, BLAST analysis was performed based on the 16S rRNA gene sequence of the strain. The results showed that the homology of this strain with the 16S rRNA gene sequence of Paenibacillus pabuli strain Plu29 (accession number MK737158.1) was 99.79%, with the 16S rRNA gene sequence of Paenibacillus amylolyticus S124 (accession number AY509232.1) was 99.57%, with the 16S rRNA gene sequences of Paenibacillus vandeheii (accession number OQ836669.1) and Paenibacillus taichungensis Rz1.2-8 (accession number MN098861.1) was 99.29%, and with the 16S rRNA gene sequence of Paenibacillus xylanivorans A59 (accession number KT461879.1) was 99.08%. As Figure 3 shown, the phylogenetic analysis of the 16S rRNA gene indicated that this strain had the closest phylogenetic relationship with Paenibacillus pabuli. Combining its cell morphology and colony characteristics, this strain was identified as Paenibacillus sp.

[0051] However, the accurate classification of this strain cannot be determined solely by 16S rRNA gene sequencing analysis. Further, whole-genome sequencing was performed on it: The extracted whole genome was sent to Shanghai Personal Biotechnology Co., Ltd. for second-generation sequencing. The obtained sequence results were subjected to average nucleotide identity (ANI) analysis with the whole-genome sequences of the reference strains of closely related species Paenibacillus pabuli NBRC13638, Paenibacillus amylolyticus SQR-21, Paenibacillus vandeheii F6_3S_P_1C, Paenibacillus taichungensis 53B, and Paenibacillus xylanivorans A59 in the NCBI database. When the ANI value is greater than 95%, the two can be considered to be of the same bacterial species. The ANI results were shown as 81.91%, 90.13%, 82.16%, 82.16%, and 82.12% respectively, indicating that this strain is different from the above-mentioned closest related species and is a potential new species. The GD-2 strain was deposited in the General Microbiological Center of the China Committee for Culture Collection of Microorganisms, and the deposit number is CGMCC No. 31835.

[0052] Example 2 Carbon fixation enzyme activity of Paenibacillus carboniphilus GD-2

[0053] To determine the carbon fixation ability of Paenibacillus sp. GD-2, the colonies of Paenibacillus sp. GD-2 purified in Example 1 were picked and inoculated into 10 mL of a liquid medium without organic carbon source (the same as in Example 1), and cultured at 28 °C and 160 r / min for 5 days. The bacterial liquid (10 5 CFU / mL) at the end of the culture was taken for RubisCO enzyme activity determination. The ribulose-1,5-bisphosphate carboxylase / oxygenase (RuBisCO) kit provided by Beijing Biosynthesis Biotechnology Co., Ltd. was used for the determination. At the same time, the BCA protein concentration determination kit was used to measure the total protein content of the bacterial liquid, and the RuBisCO enzyme activity determination results were standardized. The specific measurement method refers to the kit instruction manual.

[0054] The original data of this example was preliminarily sorted out using Microsoft Excel Office 2016 software. The experimental results were plotted using Graphpad Prism 9.5. The measurement results are shown in Figure 4 , where GD-2 is the Paenibacillus sp. GD-2 deposited in the present invention, and 1-4 are the other 4 carbon-fixing bacteria isolated and purified in Example 1.

[0055] From Figure 4It can be seen that the RuBisCO enzyme activity of Bacillus sp. GD-2 is about 19.6 U / mg prot, which is much higher than that of the other 4 carbon-fixing bacteria, indicating that it has good carbon-fixing ability.

[0056] Example 3 Study on the carbon-fixing ability of Bacillus sp. GD-2 under different conditions

[0057] The formula of the culture medium used in this example is as follows:

[0058] Carbon-free liquid medium: Na2HPO4 0.5 g / L, KH2PO4 0.5 g / L, MgSO4 0.3 g / L, CaCl2 0.2 g / L, NH4Cl 0.5 g / L, NaNO3 0.25 g / L, NaCl 0.4 g / L, trace element solution 10 mL / L, pH value is 7.0. The formula of the trace element solution is: FeCl2 0.3 g / L, FeSO4·7H2O 0.3 g / L, MnSO4·H2O 0.15 g / L, ZnSO4·7H2O 0.25 g / L, CoCl2 0.2 g / L.

[0059] Na2CO3 liquid medium: Based on the carbon-free liquid medium, add Na2CO3 0.63 g / L, pH value is 7.0.

[0060] NaHCO3 liquid medium: Based on the carbon-free liquid medium, add NaHCO3 0.5 g / L, pH value is 7.0.

[0061] NaNO2 liquid medium: NaNO2 4.6 g / L, Na2HPO4 0.5 g / L, KH2PO4 0.5 g / L, MgSO4 0.3 g / L, CaCl2 0.2 g / L, NaHCO3 0.5 g / L, NH4Cl 0.5 g / L, NaNO3 0.25 g / L, NaCl 0.4 g / L, pH value is 7.0.

[0062] Na2S2O3 liquid medium: Replace NaNO2 4.6 g / L in the NaNO2 liquid medium with Na2S2O3 5 g / L, pH value is 7.0.

[0063] Study on the carbon-fixing ability of Bacillus sp. GD-2 under different inorganic carbon sources and different electron donors

[0064] Pick the colony of Bacillus sp. GD-2 purified in Example 1 and inoculate it into 5 mL of carbon-free liquid medium, and culture it at 28 °C, 160 r / min for 5 days. Take the bacterial liquid at the end of the culture (10 51 mL (CFU / mL), after measuring the strain abundance using a flow cytometer, 400 μL was taken and inoculated into 5 mL of carbon-free liquid medium (denoted as CO2), Na2CO3 liquid medium, NaHCO3 liquid medium, NaNO2 liquid medium, and Na2S2O3 liquid medium respectively, and 3 replicates were set. After culturing at 28 °C for 5 days, the strain abundance in the bacterial liquid was detected again. The specific measurement method of microbial abundance is as follows: After diluting SYBR-Green (10000×, Solarbio) 100 times, it was mixed with propidium iodide (PI, Solarbio) at a volume ratio of 50:1 (SYBR-Green:PI) to obtain a fluorescent dye. After passing 1 mL of the bacterial liquid through a 300-mesh nylon sieve to remove large particle impurities, 10 μL of the fluorescent dye was added and stained in the dark for 15 minutes, and then vortexed and detected to determine the number of viable bacteria.

[0065] The data in this example was analyzed using CytExpert SRT software and then preliminarily sorted using Microsoft Excel Office 2016 software. The experimental results were plotted using Graphpad Prism 9.5. The results are shown in Figure 5 .

[0066] Since during the strain culture process, the available carbon sources are only atmospheric carbon dioxide and inorganic carbon sources in the medium, the increase in strain biomass all comes from carbon fixation by the strain. The results show that in the presence of only atmospheric carbon dioxide, the strain concentration of Paenibacillus sp. GD-2 can increase by 331.79 Events / μL per day, indicating that it has a certain ability to fix atmospheric carbon dioxide. When an external inorganic carbon source is added, the daily average growth rate of its strain increases, especially when NaHCO3 is added, its carbon fixation ability is significantly improved (nearly ten times), and the daily average growth rate of the strain can reach 3232.25 Events / μL. This may be the result of the strain fixing carbon through other pathways. When an external electron donor is added, the carbon fixation ability of the strain does not increase, but is weakened to varying degrees. When Na2S2O3 is added, its daily average growth rate is 851.09 Events / μL, and when NaNO2 is added, the growth of the strain cannot even be detected.

[0067] The above results show that Paenibacillus sp. GD-2 can grow in a very low-nutrient salt medium, does not need to rely on an electron donor, and has a higher carbon fixation potential in a soil environment with a high content of carbonates and bicarbonates, which helps to develop the application of the strain in special environments (such as soda saline-alkali land).

[0068] Example 4 Analysis of the carbon fixation pathway of Paenibacillus sp. GD-2

[0069] 1. Materials and methods

[0070] The Paenibacillus GD-2 isolated and identified in Example 1 was sent to Shanghai Personal Biotechnology Co., Ltd. for second-generation sequencing using the Illumina Novaseq platform. A whole-genome framework map was assembled and spliced, and bioinformatics software and databases were used to annotate and functionally identify the bacteria. The carbon fixation pathway of strain GD-2 was speculated through the KEGG database, providing a basis for studying the carbon fixation ability of the strain.

[0071] 2. Results and Analysis

[0072] Based on the KEGG database, the CO2 fixation pathway of strain GD-2 was clarified. First, CO2 was fixed by phosphoenolpyruvate to generate oxaloacetate, which was converted to L-aspartate under the action of aspartate aminotransferase, and then further converted to threonine. Threonine was cleaved by threonine aldolase into glycine, and glycine was converted to serine by glycine hydroxymethyltransferase, and finally converted to pyruvate under the action of serine dehydrogenase to form a carbon fixation cycle ( Figure 6 ). The first stable product produced when this pathway fixes CO2 is the four-carbon compound oxaloacetate. Through the transformation of various amino acids, the renewal of phosphoenolpyruvate is finally achieved, and the synthesis and degradation of threonine are the core processes in this cycle. In addition, biological carbon fixation is usually completed under the catalysis of a series of enzymes. Strain GD-2 can also achieve the reaction of acetyl-CoA and HCO3 - to generate malonyl-CoA under the catalysis of the enzyme with higher carbon fixation efficiency, i.e., acetyl-CoA carboxylase (ACC). This step of reaction is the first step of fatty acid synthesis and the synthesis of other substances, which also explains to a certain extent the phenomenon that the addition of the inorganic carbon source NaHCO3 significantly improves the carbon fixation ability of this strain.

[0073] Study on the Induced Generation of Carbon-containing Minerals by the Carbon-fixing Bacterium Paenibacillus sp. GD-2 in Example 5

[0074] 1. Materials and Methods

[0075] 1.1 Test strain: Paenibacillus GD-2, isolated and identified in Example 1.

[0076] Urea broth liquid medium: Peptone 1.0 g / L, Glucose 1.0 g / L, NaCl 5.0 g / L, Na2HPO4 1.2 g / L, KH2PO4 0.8 g / L, Phenol Red 0.004 g / L; pH 7.0.

[0077] 1.2 Detection and Analysis of Carbon-containing Minerals Generated by the Carbon-fixing Bacterium Paenibacillus GD-2

[0078] The Paenibacillus sp. GD-2 colonies purified in Example 1 were inoculated into 10 mL of urea broth liquid medium and cultured at 28 °C, 160 r / min for 5 days. A control group without inoculating the strain was set up. At the end of the culture, 1 mL of the bacterial liquid was added to 1 mL of a CaCl2·2H2O solution with a concentration of 350 mmol / L, placed in a shaker for 15 min, centrifuged at a speed of 16179 g for 5 min, and then the precipitate was placed in an oven at 50 °C and dried for 24 h and weighed. Further, the precipitate was subjected to electron microscopy scanning and energy dispersive diffraction analysis to explore the morphological structure and elemental composition information of the precipitate.

[0079] 2. Results and Analysis

[0080] After the culture was completed, a total of 8.9 mg of precipitate was obtained. Scanning electron microscopy showed ( Figure 7 ) that the precipitate had a flaky structure and a pore structure where microorganisms lived. According to energy dispersive diffraction analysis, the main components of the precipitate were carbon, oxygen, and calcium, and the atomic percentages were close to 1:3:1 ( Figure 7 and Table 1). Therefore, it was judged that this precipitate was calcium carbonate, indicating that the Paenibacillus sp. GD-2 had the ability to generate carbon-containing minerals and could convert carbon dioxide in the atmosphere or inorganic carbon in the medium into carbonate minerals through the metabolic process, thereby achieving carbon fixation (mineralization carbon fixation).

[0081] Table 1 Elemental composition of the precipitate

[0082] Element type Atomic percentage (%) Carbon 13.29 Oxygen 65.38 Calcium 21.33 Total 100

[0083] In summary, the Paenibacillus sp. GD-2 screened in the present invention has the dual carbon fixation ability to fix inorganic carbon as organic carbon or inorganic carbon, that is, it can convert carbon dioxide in the atmosphere or inorganic carbon in the medium into carbonate minerals, and can also use carbon dioxide or inorganic carbon in the medium to convert into its own biological carbon (organic carbon) for growth, providing strain resources for improving the carbon fixation and emission reduction ability of saline-alkali soil, providing technical support for in-depth understanding of the microbial regulation process of the occurrence form of nutrients in saline-alkali soil, laying a foundation for proposing soil microbial improvement technology in photovoltaic fields, and promoting the high-quality development of the photovoltaic industry in fragile saline-alkali areas.

[0084] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A Paenibacillus sp. GD-2, with the deposit number of CGMCC No. 31835.

2. A carbon-fixing microbial inoculant, characterized in that, Including the Paenibacillus GD-2 described in claim 1.

3. The carbon-fixing microbial inoculant according to claim 2, wherein The OD of Paenibacillus sp. GD-2 in the carbon sequestration microbial inoculum 600 value ≥ 0.

6.

4. The preparation method of the carbon-fixing microbial inoculant according to claim 2 or 3, characterized in that, Including the following steps: Inoculate the Paenibacillus GD-2 described in claim 1 into a medium for cultivation to obtain the carbon fixation microbial inoculant; the medium includes a medium without an organic carbon source.

5. The preparation method according to claim 4, characterized in that, The medium without an organic carbon source includes components with the following concentrations: 0.5 g / L of Na2HPO4, 0.5 g / L of KH2PO4, 0.3 g / L of MgSO4, 0.2 g / L of CaCl2, 0.5 g / L of NH4Cl, 0.25 g / L of NaNO3, 0.4 g / L of NaCl, 10 mL / L of trace element solution; the trace element solution includes components with the following concentrations: 0.3 g / L of FeCl2, 0.3 g / L of FeSO4·7H2O, 0.15 g / L of MnSO4·H2O, 0.25 g / L of ZnSO4·7H2O, 0.2 g / L of CoCl2; the pH value of the medium without an organic carbon source is 7.0 - 7.

4.

6. The preparation method according to claim 4 or 5, characterized in that, The medium without an organic carbon source further includes an inorganic carbon source; the inorganic carbon source includes sodium bicarbonate and / or sodium carbonate.

7. The preparation method according to claim 4, characterized in that, The cultivation time is 5 - 7 days; the cultivation temperature is 28 °C.

8. The application of the Paenibacillus GD-2 described in claim 1 or the carbon fixation microbial inoculant described in claim 2 or 3 in carbon fixation, and the carbon source for carbon fixation includes an inorganic carbon source.

9. The application according to claim 8, characterized in that The inorganic carbon source includes one or more of carbon dioxide, sodium bicarbonate, and sodium carbonate.

10. The application according to claim 8 or 9, characterized in that, The carbon fixation includes: inducing the inorganic carbon source to generate carbon-containing minerals and / or using the inorganic carbon source to be converted into its own biological carbon.

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