Microbial agent for degrading lignin and application of microbial agent in regulation and control of soil organic carbon library

Abstract

The invention provides a microbial agent capable of degrading lignin and application of the microbial agent in regulation and control of a soil organic carbon library, and relates to the technical field of microorganisms, the microbial agent contains at least two of serratia marcescens, ochrobactrum anthropi, pseudomonas asparagi or burkholderia terricola, and the microbial agent contains at least two of the serratia marcescens, the ochrobactrum anthropi, the pseudomonas asparagi and the burkholderia terricola. The serratia marcescens a26, the ochrobactrum anthropi b1, the pseudomonas asparagi b6 or the burkholderia terricola b21 have good lignin degradation capability, after compounding, the lignin degradation capability of the strain is further improved, and the strain can be used for degrading moso bamboo litters with high lignin content and promoting accumulation of a soil organic carbon library. The technical problem that a microbial agent with a function of efficiently degrading lignin is lacked in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to a microbial agent for degrading lignin and its application in regulating soil organic carbon pools. Background Technology

[0002] Normally managed moso bamboo forests are thinned every two years, leaving behind a large amount of stumps and litter. For example, the total amount of litter produced by moso bamboo each year is 6.48 tons per hectare. The lignin content in these stumps and litter is as high as 34%, significantly higher than the lignin content (25%) in the litter of broad-leaved forests in the same area. The relatively high lignin content is not conducive to its natural decomposition, resulting in slow degradation. This makes it difficult for stumps and litter in bamboo forests to decompose in the short term, seriously hindering the normal development of underground rhizomes, high-quality management of bamboo forests, and nutrient recycling, which is detrimental to the improvement of bamboo forest productivity.

[0003] Lignin is the most difficult part of plant cell walls to degrade. Lignin-degrading bacteria can break down this complex organic compound into simpler organic matter. Currently, there are few lignin-degrading bacteria used for the decomposition of bamboo stumps and litter, and related studies often only focus on their degradation effects, neglecting the impact of lignin degradation on the soil organic carbon pool.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One of the objectives of this invention is to provide a microbial agent for degrading lignin, thereby solving the technical problem of the lack of a microbial agent with efficient lignin degradation function in the prior art.

[0006] The second objective of this invention is to provide a method for preparing the aforementioned microbial inoculant.

[0007] A third objective of this invention is to provide the application of the above-mentioned microbial inoculant or the microbial inoculant prepared by the above-mentioned preparation method in the degradation of lignin or the preparation of products for the degradation of lignin.

[0008] The fourth objective of this invention is to provide a product.

[0009] The fifth objective of this invention is to provide the application of the above-mentioned microbial agents, the microbial agents prepared by the above-mentioned method, and the above-mentioned products in degrading litter or regulating the soil organic carbon pool.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a microbial agent for degrading lignin, containing at least two of Serratia marcescens, Paleobacterium humanis, Pseudomonas azureina, or Burkholderia territorialis. The *Serratia marcescens* is *Serratia marcescens* (… Serratia marcescens a26, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251518; The human pallidum is human pallidum ( Ochrobactrum anthropi b1, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251521; The *Pseudomonas asseudomonas* is *Pseudomonas asseudomonas* (… Pseudomonas asuensis b6, which is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251520; The Burkholderia territorialis is Burkholderia territorialis ( Burkholderia territorii b21 is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251519.

[0011] Furthermore, it contains Serratia marcescens a26, Paleobacterium humanis b1, and Pseudomonas asseudomonas b6.

[0012] Furthermore, it contains Serratia marcescens a26, Paleobacterium humanis b1, and Burkholderia territorialis b21.

[0013] Furthermore, Serratia marcescens a26, Paleobacterium humanis b1, Pseudomonas asseudomonas b6, and Burkholderia territorialis b21 all existed in the form of living cells.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned microbial inoculant, comprising mixing single microbial inoculants in equal volume ratios to obtain the microbial inoculant.

[0015] Furthermore, the OD of the single microbial culture 600nm It is 0.1.

[0016] Thirdly, the present invention provides the application of the above-mentioned microbial inoculant or the microbial inoculant prepared by the above-mentioned preparation method in the degradation of lignin or the preparation of products for the degradation of lignin.

[0017] Fourthly, the present invention provides a product whose active ingredient includes at least one of the above-mentioned microbial inoculants and the microbial inoculants prepared by the above-mentioned preparation method.

[0018] Fifthly, the present invention provides the application of the above-mentioned microbial inoculant, the microbial inoculant prepared by the above-mentioned preparation method, and the above-mentioned product in degrading litter or regulating the soil organic carbon pool. Furthermore, the regulation of the soil organic carbon pool includes increasing the content of total soil organic carbon or promoting the conversion of particulate organic carbon in the soil into mineral-bound organic carbon.

[0019] This invention provides a microbial agent for degrading lignin. *Serratia marcescens* a26, *Ailuropoda spp.* b1, *Pseudomonas asseudomonas* b6, or *Burkholderia territorialis* b21 all possess good lignin-degrading capabilities. When combined, their lignin-degrading ability is further enhanced, and they can be used for the degradation of bamboo litter with high lignin content. This invention solves the technical problem of the lack of a microbial agent with highly efficient lignin-degrading function in the prior art. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 These are comparative photographs of the clear zones of lignin-degrading bacteria on lignin screening medium provided in Example 2 of the present invention. Figure 2 The aniline blue decolorization rate of the two-strain and three-strain microbial agents provided in Example 4 of the present invention is shown in the following statistical chart. Figure 3 The effect of leaf-inoculated and root-inoculated microbial communities on soil organic carbon content provided in Embodiment 5 of the present invention; Figure 4 The effect of leaf-inoculated microbial communities provided in Example 5 of this invention on key components of soil organic carbon; Figure 5 The effect of root-inoculated microbial communities on key components of soil organic carbon provided in Example 5 of this invention. Detailed Implementation

[0022] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The present invention provides a microbial inoculant for degrading lignin, containing at least two of Serratia marcescens, Paleobacterium humanis, Pseudomonas asseudomonas azureii, or Burkholderia territorialis. The *Serratia marcescens* is *Serratia marcescens* (… Serratia marcescens a26, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251518; The human pallidum is human pallidum ( Ochrobactrum anthropi b1, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251521; The *Pseudomonas asseudomonas* is *Pseudomonas asseudomonas* (… Pseudomonas asuensis b6, which is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251520; The Burkholderia territorialis is Burkholderia territorialis ( Burkholderia territorii b21 is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251519.

[0025] Preservation Instructions for Serratia marcescens Strain name: Serratia marcescens a26; Latin name: Serratia marcescens ; Preservation institution: China Center for Type Culture Collection; Abbreviation for depository institution: CCTCC; Address: Wuhan University, Wuhan City, Hubei Province; Deposit date: July 2, 2025; Collection Center Accession Number: CCTCC NO: M 20251518.

[0026] Preservation instructions for human paleobacterium b1 Bacterial strain name: Human anthrax b1; Latin name: Ochrobactrum anthropi ; Preservation institution: China Center for Type Culture Collection; Abbreviation for depository institution: CCTCC; Address: Wuhan University, Wuhan City, Hubei Province; Deposit date: July 2, 2025; Collection Center Accession Number: CCTCC NO: M 20251521.

[0027] Preservation instructions for Pseudomonas aeruginosa b6 Bacterial species name: Pseudomonas assueri b6; Latin name: Pseudomonas asuensis ; Preservation institution: China Center for Type Culture Collection; Abbreviation for depository institution: CCTCC; Address: Wuhan University, Wuhan City, Hubei Province; Deposit date: July 2, 2025; Collection Center Accession Number: CCTCC NO: M 202515120.

[0028] Preservation instructions for Burkholderia territories b21 Strain name: Burkholderia territorialis b21; Latin name: Burkholderia territorii ; Preservation institution: China Center for Type Culture Collection; Abbreviation for depository institution: CCTCC; Address: Wuhan University, Wuhan City, Hubei Province; Deposit date: July 2, 2025; Collection Center Accession Number: CCTCC NO: M 20251519.

[0029] Serratia marcescens a26, Aristolochic acid b1, Pseudomonas asseudomonas b6, or Burkholderia territorialis b21 all possess good lignin degradation capabilities. When combined, their lignin degradation capabilities are further enhanced, and they can be used to treat bamboo forest soils with high lignin content. This addresses the technical problem of the lack of a highly efficient lignin-degrading microbial agent in existing technologies.

[0030] In some specific embodiments, it contains Serratia marcescens a26, Paleobacterium humanis b1, and Pseudomonas asseudomonas b6.

[0031] In some specific embodiments, it contains Serratia marcescens a26, Paleobacterium humanis b1, and Burkholderia territorialis b21.

[0032] In some specific embodiments, Serratia marcescens a26, Paleobacterium humanis b1, Pseudomonas asseudomonas b6, and Burkholderia territorialis b21 are all present in the form of living cells.

[0033] According to another aspect of the present invention, a method for preparing the above-mentioned microbial inoculant is also provided, comprising mixing single microbial inoculants in equal volume ratios according to a formula to obtain the microbial inoculant.

[0034] In some specific embodiments, the OD of the single microbial culture 600nm It is 0.1.

[0035] According to another aspect of the present invention, the application of the above-described microbial agent or the microbial agent prepared by the above-described preparation method in the degradation of lignin or the preparation of products for the degradation of lignin is also provided.

[0036] According to another aspect of the present invention, a product is also provided, the active ingredient of which includes at least one of the above-described microbial inoculant and the microbial inoculant prepared by the above-described preparation method.

[0037] According to another aspect of the present invention, the application of the above-mentioned microbial inoculant, the microbial inoculant prepared by the above-mentioned preparation method, and the above-mentioned product in degrading litter or regulating the soil organic carbon pool is also provided. In some specific implementations, regulating the soil organic carbon pool includes increasing the total organic carbon content of the soil or promoting the conversion of particulate organic carbon in the soil into mineral-bound organic carbon.

[0038] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0039] Tryptone soybean broth medium (TSB medium): 17.0 g tryptone, 3.0 g plant peptone, 2.5 g dipotassium hydrogen phosphate, 5.0 g sodium chloride, 2.5 g glucose, and water to a final volume of 1000 mL, pH 7.3 ± 0.2.

[0040] Aniline blue medium: 17.0 g tryptone, 3.0 g plant peptone, 2.5 g dipotassium hydrogen phosphate, 5.0 g sodium chloride, 2.5 g glucose, 3 g aniline blue, and water to a final volume of 1000 mL, pH at natural.

[0041] Example 1: Isolation, Screening and Identification of Lignin-Degrading Bacteria 1. Preliminary isolation and screening of lignin-degrading bacteria Rhizosphere soil, as a key interface for plant-microbe interaction, provides natural screening conditions for the ecological niche selection and functional enrichment of lignin-degrading bacteria due to its unique physicochemical properties and dynamic metabolic characteristics. Therefore, this study selected rhizosphere soil as the target sample to isolate and obtain indigenous microbial resources with efficient lignin decomposition capabilities.

[0042] The experimental plots were located at the Long-Term Moso Bamboo Forest Experimental Platform in Lin'an District, Hangzhou City, Zhejiang Province (30.24°N, 119.42°E). Three 20 m × 20 m quadrats of Moso bamboo forest were randomly set up within the experimental plots. Five 1-year-old and 3-year-old standard Moso bamboo plants were selected from each quadrat based on their average diameter at breast height (DBH). The rhizosphere soil and fine roots (≤2 mm in diameter) of the rhizosphere roots and connected rhizomes (BRs) of the standard plants in each quadrat were collected using the root-shaking method. After thorough mixing, the samples were placed in a sample collection box and transported to the laboratory for the isolation of lignin-degrading strains.

[0043] Place 3 g of root sample (including soil) into a 50 ml sterile centrifuge tube, then add 40 mL of sterile phosphate buffered saline solution (PBS solution, pH=5), and incubate at 30℃ and 180 r·min. -1 Rhizosphere soil fungi suspension was obtained by incubation in a shaker for 15 min. Microplate high-throughput screening was employed using 10% aniline blue liquid medium (TSB medium supplemented with 3 g·L⁻¹). -1 Aniline blue was used as the screening medium, and the suspension was diluted in 5 gradients (10⁻⁶ ppm). -3 10 -4 10 -5 10 -6 and 10 -7 Screening for lignin-degrading bacteria was conducted. The optimal dilution gradient was determined when 30% of the wells in the culture plate showed visibly decolorized conditions. Using this optimal dilution gradient, plating was performed. After single colonies grew, they were picked and streaked onto aniline blue agar to isolate pure strains. The culture conditions were 30°C in the dark. Preliminary screening yielded 80 strains.

[0044] 2. Molecular identification DNA was extracted from the bacterial strains using the SPARKeasy Bacterial Genomic DNA Rapid Extraction Kit (Shandong Cisco Biotechnology Co., Ltd.). 16S rRNA sequencing was performed on the DNA using universal bacterial primers 27F: 5'-AGAGTTTGATCMTGGCTCAG-3' and 1492R: 5'-TACGGYTACCTTGTTACGACTT-3'. The obtained strain sequences were then selected using BLAST alignment in NCBI, followed by phylogenetic analysis using MEGA-X. A phylogenetic tree was constructed using the neighbor-joining method to identify 80 strains.

[0045] 3. Selected strains The lignin degradation capacity and enzyme activity of the above 80 strains were measured respectively. From the strains with the strongest lignin degradation capacity, strains from different genera were selected as preferred strains. The synthetic strains were obtained by using the standard that the aniline blue decolorization rate of the combined strains was greater than that of the single strains. Finally, four strains were obtained, namely a26, b1, b6 and b21.

[0046] Based on molecular identification results, strain a26 is *Serratia marcescens* (…). Serratia marcescens b1 is human pale bacillus ( Ochrobactrum anthropi b6 is Pseudomonas assuarii ( Pseudomonas asuensis b21 is Burkholderia territorialis ( Burkholderia territorii ).

[0047] Example 2: Lignin Degradation Capacity of Lignin-Degrading Bacteria This embodiment measures the lignin degradation ability of the four strains screened in Example 1.

[0048] 1. Clear zone determination: Single colonies obtained from isolation were inoculated onto aniline blue solid medium and incubated at 30°C for 3 days. The presence or absence of a clear zone was observed. The ratio of the clear zone diameter (D) to the colony diameter (d) (D / d) was used to preliminarily determine the lignin-degrading ability of the strain. The culture results are shown below. Figure 1 As shown.

[0049] 2. Determination of aniline blue decolorization rate: The isolated pure strains were inoculated into 24-well plates containing aniline blue medium and placed in a shaker at 180 rpm·min. -1 Incubate at 30℃ for 3 days. Stir the culture medium at 3000 rpm·min. -1 Centrifuge for 10 min, collect the supernatant, add it to an ELISA plate, and measure the absorbance at 590 nm using an ELISA reader. Substitute the absorbance into the standard curve to calculate the remaining dye content in the supernatant, and then calculate the decolorization rate using the formula: ; In the formula, C t C0 represents the remaining dye content; C0 represents the dye content in the control.

[0050] The higher the decolorization rate, the stronger the degradation ability.

[0051] 3. Determination of enzyme activity of lignin-degrading bacteria The strain was inoculated into TSB medium and placed on a shaker at 180 rpm·min. -1 Incubate at 30℃ for 3 days. Stir the culture medium at 10000 rpm·min. -1 Centrifuge for 10 min, and the supernatant is the crude enzyme solution. The activities of lignin peroxidase (LiP) and manganese peroxidase (MnP) were determined using the Tian Shuanglin method, and the activity of laccase (Lac) was determined using the ABTS method.

[0052] The results of D / d ratio, decolorization rate and enzyme activity determination are shown in Table 1.

[0053] Table 1

[0054] Note: Different lowercase letters in the same column indicate significant differences between strains (P<0.05). The results of D / d ratio, decolorization rate, and enzyme activity assays showed that all four strains possessed high lignin degradation capabilities. Specifically, b1 had the highest D / d ratio; a26 exhibited the highest lignin degradation capability in decolorization rate, followed by b6; a26 showed the highest LiP and Lac enzyme activities, followed by b21 with relatively high Lac enzyme activity; and b6 had the highest MnP enzyme activity.

[0055] Example 3: Preparation of Microbial Inoculants This invention uses four strains screened in Example 1 for preparation, specifically including the following steps: 1. Preparation of single-strain microbial inoculants: The strain was inoculated into TSB and cultured until OD600nm=0.1, which was then used to prepare compound microbial inoculants.

[0056] 2. Two-strain compound microbial inoculant: Take the culture broth (OD) of two strains of bacteria respectively. 600nm =0.1 (can be adjusted with sterile water), mix according to a 1:1 ratio.

[0057] 3. Three-strain compound microbial inoculant: Take the culture broth (OD) of each of the three strains of bacteria. 600nm =0.1 (can be adjusted with sterile water), mix according to a 1:1:1 ratio.

[0058] Example 4: Lignin Degradation Capacity of Microbial Agents The microbial inoculant prepared in Example 3 was inoculated into aniline blue liquid medium at an inoculum volume of 10%, and then placed in an incubator at 30°C and 180 rpm. -1 The sample was incubated in the dark for 36 h to determine the aniline blue decolorization rate, using the same method as described in Example 2.

[0059] The results are as follows Figure 2 As shown, A represents a two-strain complex, and B represents a three-strain complex. Data shows that the aniline blue decolorization rate was highest in the two-strain complexes (a26×b21, a26×b1, a26×b6 combinations), ranging from 55.96% to 58.74%, but all lower than that of a26 alone. In the three-strain complex, the synthetic flora composed of a26×b1×b6 strains showed the highest aniline blue decolorization rate, reaching 63.91%, followed by a26×b1×b21... Figure 2 The lignin degradation effect of the B-type microbial agent was higher than that of the two-microbial combination and the single-microbial agent, indicating that the single microorganisms in the above combination have a synergistic effect and can cooperate to improve the decolorization rate and enhance the lignin degradation ability. The a26×b1×b6 three-microbial compound agent with the highest decolorization rate was selected as the representative for subsequent experiments on the impact on the soil organic carbon pool.

[0060] Example 5: Effects of microbial inoculants on the soil organic carbon pool of moso bamboo forests 1. Method Soil used for testing: Soil for potted plants was collected from the long-term bamboo forest experimental platform in Lin'an District, Hangzhou City, Zhejiang Province (30.24°N, 119.42°E). Soil (0-20 cm soil layer) from normally managed bamboo forests was collected. This area is located on the northern edge of the mid-subtropical monsoon climate zone, with four distinct seasons, mild climate, abundant rainfall, an average annual precipitation of about 1420 mm, an average annual temperature of 15.6℃, and an average frost-free period of about 230 days.

[0061] Litter: Bamboo leaves and roots were collected in June 2023 and transported to the laboratory for drying at 60℃. The leaves were cut into 1×1cm pieces, and the roots were crushed and passed through a 20-mesh sieve for later use.

[0062] Weigh out 150 g of air-dried soil into a tissue culture bottle, add 2% (w / w) of fallen bamboo leaves and the same amount of bamboo rootlets, and mix thoroughly. Administer the mixed inoculum of single, double, and triple bacteria as a bacterial suspension (1×10⁻⁶). 10 CFU·mL -1 The inoculum was evenly sprayed onto the soil surface mixed with roots or leaves in the form of a 1% inoculum, and inoculated once per quarter. A control group was not inoculated. A total of 16 treatments were conducted, with 5 replicates per treatment. Water was replenished weekly by weight. Soil samples were collected at 90, 180, and 270 days after the first inoculation. The collected soil samples were passed through a 20-mesh sieve to separate undecomposed leaves and soil, which were used for subsequent parameter determination.

[0063] Determination of total organic carbon content in soil: Organic carbon (SOC) was determined using the potassium dichromate oxidation-spectrophotometric method.

[0064] Determination of particulate organic carbon (POC) and mineral-bound organic carbon (MAOC) in soil: Extraction and determination were performed using sodium hexametaphosphate extraction method. Approximately 10 g of air-dried soil passing through a 2 mm pore size was dissolved in 30 ml of 5 g / L sodium hexametaphosphate solution and shaken for 18 h. The soil aggregates were then separated into two particle sizes by passing through a 53 µm sieve: >53 µm was particulate organic matter (POM, which did not pass through the sieve), and <53 µm was mineral-bound organic matter (MAOM, which passed through the sieve). After drying, the organic carbon content in POM and MAOM was determined using the potassium dichromate oxidation method.

[0065] 2. Results 1) Total organic carbon content in soil like Figure 3As shown, A represents leaf input and B represents root input. Compared with the control (no inoculation), under leaf input, inoculation with a26×b1×b6 significantly increased soil SOC content by day 180. P <0.05), with an increase of 35.41%. At day 270 of cultivation, inoculation with a26×b6, b1×b6, and a26×b1×b6 significantly increased soil SOC content, with increases of 22.91%, 41.39%, and 29.34%, respectively. P <0.05). Under root input, inoculation with a26 single bacteria significantly increased soil SOC content at day 180, and inoculation with a26×b1 significantly increased soil SOC content at day 270.

[0066] 2) Key components of soil organic carbon like Figure 4 As shown, A represents POC, B represents MAOC, C represents POC / SOC, and D represents MAOC / SOC. Under leaf input, compared with the control (CK), at day 90 of cultivation, inoculation with a26 and b1 significantly increased soil MAOC, while POC showed no significant change. At day 180 of cultivation, all inoculation agents increased POC and its proportion in SOC, with inoculation with a three-strain synthetic agent showing the most significant increase in POC and its proportion in SOC. However, all inoculation treatments significantly decreased MAOC and its proportion in SOC (except for a26). At day 270 of cultivation, inoculation with b1×b6 agent significantly increased POC, while inoculation with b1, as well as with two-strain and three-strain agents, increased MAOC. However, the proportions of POC and MAOC in SOC did not change significantly.

[0067] like Figure 5 As shown, A represents POC, B represents MAOC, C represents POC / SOC, and D represents MAOC / SOC. Under root input conditions, at day 90 of culture, inoculation with single strains a26 and b6 both reduced POC and its proportion in SOC, while inoculation with b6 significantly increased the proportion of MAOC in SOC. At day 180 of culture, the contents of POC and MAOC did not change significantly compared with the control, while inoculation with a26 and a26×b1 significantly reduced the proportion of MAOC. At day 270 of culture, inoculation with both strains significantly increased the proportion of POC in SOC, but decreased the proportion of MAOC in SOC.

[0068] It was found that, under leaf input, inoculation with a26×b6, b1×b6, and a26×b1×b6 significantly increased soil SOC content, but did not change the proportion of POC and MAOC in SOC, indicating that it maintained the stability of soil organic carbon while improving soil carbon sequestration. Under root input, inoculation with the two-microbial combination increased root degradation and promoted POC formation. Inoculation with the a26×b1 combination significantly increased soil organic carbon content and had a better effect on soil carbon sequestration.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microbial inoculant for degrading lignin, characterized in that, It contains at least two of the following: Serratia marcescens, Paleobacterium humanis, Pseudomonas azumi, or Burkholderia territorialis. The *Serratia marcescens* is *Serratia marcescens* (… Serratia marcescens a26, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251518; The human pallidum is human pallidum ( Ochrobactrum anthropi b1, which is deposited in the China Center for Type Culture Collection, with accession number CCTCC NO: M 20251521; The *Pseudomonas asseudomonas* is *Pseudomonas asseudomonas* (… Pseudomonas asuensis b6, which is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251520; The Burkholderia territorialis is Burkholderia territorialis ( Burkholderia territorii b21 is deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 20251519.

2. The microbial agent according to claim 1, characterized in that, It contains Serratia marcescens a26, human paleobacterium b1, and Pseudomonas asseudomonas b6.

3. The microbial agent according to claim 1, characterized in that, It contains Serratia marcescens a26, Paleobacterium humanis b1, and Burkholderia territorialis b21.

4. The microbial inoculant according to any one of claims 1 to 3, characterized in that, Serratia marcescens a26, Paleobacterium humanis b1, Pseudomonas asseudomonas b6, and Burkholderia territorialis b21 all exist in the form of living cells.

5. The method for preparing the microbial inoculant according to any one of claims 1 to 4, characterized in that, This includes mixing single microbial inoculants in equal volume ratios to obtain microbial agents.

6. The preparation method according to claim 5, characterized in that, OD of the single microbial culture 600nm It is 0.

1.

7. The use of the microbial agent according to any one of claims 1 to 4 or the microbial agent prepared by the preparation method according to claim 5 or 6 in the degradation of lignin or the preparation of products for the degradation of lignin.

8. A product characterized in that, It includes at least one of the microbial inoculants according to any one of claims 1 to 4 and the microbial inoculants prepared by the preparation method according to claim 5 or 6.

9. The application of the microbial agent according to any one of claims 1 to 4, the microbial agent prepared by the preparation method according to claim 5 or 6, and the product according to claim 8 in degrading litter or regulating the soil organic carbon pool.

10. The application according to claim 9, characterized in that, The regulation of the soil organic carbon pool includes increasing the total organic carbon content of the soil or promoting the conversion of particulate organic carbon in the soil into mineral-bound organic carbon.

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