Strain of low-temperature straw-degrading bacteria of genus zygorhynchus NJAU-F2G6 and application thereof

Abstract

The application discloses a low-temperature straw degrading bacterium, fungi of the genus Zymophiles, NJAU-F2G6, which is preserved in the China General Microbiological Culture Collection Center on March 31, 2025, and has a preservation number of CGMCC No.41876. The application discloses application of the low-temperature straw degrading bacterium in low-temperature straw degradation and in promoting crop growth. The application also discloses a bacterium agent prepared from the low-temperature straw degrading bacterium and application of the bacterium agent in low-temperature straw degradation and in promoting crop growth. The application discloses that the strain NJAU-F2G6 can promote corn straw degradation under the condition of 10 DEG C low temperature according to the results of screening test and low-temperature soil incubation test. The application discloses that the corn straw degradation rate is greatly improved and the corn plant has a good growth promoting effect in the bacterium (NJAU-F2G6) treatment compared with the non-bacterium treatment according to the results of two-season potting test. The application provides a strain resource and technical support for enhancing low-temperature straw degradation and promoting crop growth.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural microorganism technology, in particular to a low-temperature straw degrading bacterium of the genus Pediococcus NJAU-F2G6 and its application. BACKGROUND

[0002] As a large agricultural country, China has a considerable amount of straw, with a total of about 800 million tons per year, of which corn straw accounts for about 25%. Due to the large biomass of corn straw and the low collection coefficient, the treatment cost has been high, which has seriously restricted the efficient promotion of corn straw resource utilization. Among the many straw treatment methods, direct return to the field is one of the main means of straw resource utilization due to its relatively simple operation and low cost. However, a large number of studies have shown that if the straw cannot be degraded in time, it will have an adverse effect on the growth of the next crop, such as hindering seed germination and affecting root growth. The application of microbial inoculants to promote degradation has become an effective and environmentally friendly solution to accelerate straw degradation, improve soil fertility, and promote crop growth.

[0003] Northeast China is one of the main grain producing areas in China and plays a crucial role in corn planting. However, the climate in this region is cold, and the soil temperature is below 20℃ for most of the year. The planting season is from May to October, and the soil temperature is already below 10℃ by the time of harvest. The low-temperature environment greatly limits the activity of straw degrading microorganisms in the soil, making the straw degradation process extremely slow. Low degradation efficiency not only affects the timely recovery of soil fertility but also directly hinders the sowing and growth of the next crop, seriously threatening the sustainable development of local agriculture.

[0004] Although there are many corn straw degrading microbial inoculants currently available at room temperature, there is a severe lack of efficient degrading inoculant products for the low-temperature environment in Northeast China. The existing room temperature inoculants have a significantly reduced activity at low temperatures, which cannot meet the actual agricultural production needs in Northeast China. In view of this, the present application focuses on the low-temperature environment (10℃) to simulate the degradation process of corn straw under low-temperature conditions, and constructs a screening and verification system with corn straw as the main carbon source. A low-temperature straw degrading bacterium of the genus Pediococcus NJAU-F2G6 is successfully located and obtained, in order to provide strong strain resources and technical support for efficient straw return to the field in Northeast China and effectively solve the straw treatment problems in local agricultural production. SUMMARY

[0005] The purpose of the present application is to provide a low-temperature straw degrading bacterium of the genus Pediococcus NJAU-F2G6 and its application to overcome the deficiencies of the prior art.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] The application provides a low-temperature straw degrading bacteria of the genus Zymoacus, and the bacteria is named as Zymoacus sp. Epicoccum The bacteria is preserved in the China General Microbiological Culture Collection Center, and the preservation date is March 31, 2025, and the preservation number is CGMCC No.41876.

[0008] The application provides a bacterial agent prepared from the low-temperature straw degrading bacteria of the genus Zymoacus.

[0009] Further, the bacterial agent is prepared by the following method: the Zymoacus sp. with the preservation number of CGMCC No.41876 is subjected to liquid fermentation, and after the fermentation is completed, mycelium is removed by filtration to obtain a fermentation liquor, and the fermentation liquor is adjusted to obtain a spore content to obtain a bacterial suspension, that is, the bacterial agent.

[0010] Further, the bacterial agent is prepared by the following method: the Zymoacus sp. with the preservation number of CGMCC No.41876 is inoculated into a first liquid culture medium to perform liquid fermentation, the first liquid culture medium comprises a PDA liquid culture medium, the liquid fermentation condition is that the fermentation temperature is 28-30 DEG C, the rotation speed is 170-190 r / min, and the fermentation time is 96-120 h, after the fermentation is completed, mycelium is removed by multi-layer gauze filtration to obtain a fermentation liquor, the fermentation liquor is adjusted by a second liquid culture medium to obtain a spore content to obtain a bacterial suspension, that is, the bacterial agent, the second liquid culture medium comprises a 1 / 2MS liquid culture medium, and the spore content in the bacterial suspension is greater than or equal to 5*10 6 Per milliliter.

[0011] The application provides an application of the bacterial agent in low-temperature straw degradation and crop growth promotion.

[0012] Further, the straw is corn straw.

[0013] Further, the crop is corn.

[0014] The application provides an application of the bacterial agent in low-temperature straw degradation and crop growth promotion.

[0015] Further, the straw is corn straw.

[0016] Further, the crop is corn.

[0017] The application has the beneficial effects that:

[0018] The present application aims at the problem that corn stalks cannot be degraded rapidly in the low-temperature environment in the northeast region, thereby affecting the growth of the following crops, and screens out a low-temperature stalk degrading strain of fungi of the genus Zymophiles NJAU-F2G6, so as to help the efficient stalk application in the northeast region. The screening test and low-temperature soil incubation test results of the present application show that the strain NJAU-F2G6 can promote the degradation of corn stalks under the condition of 10 DEG C low temperature. The two-season potting test results of the present application show that the bacteria (NJAU-F2G6) treatment greatly improves the corn stalk degradation rate compared with the non-bacteria treatment, and has a good growth promoting effect on the corn plants. The present application provides a strain resource and technical support for enhancing the low-temperature degradation of stalks and promoting the growth of crops. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a photo of the strain NJAU-F2G6 after being cultured on PDA solid medium at 28 DEG C for 120h.

[0020] Figure 2 It is a phylogenetic tree constructed based on the 16S rRNA gene sequence of the strain NJAU-F2G6.

[0021] Figure 3 It is the influence of the strain NJAU-F2G6 treatment on the corn stalk degradation rate in the first season potting test.

[0022] Figure 4 It is the influence of the strain NJAU-F2G6 treatment on the length of the above-ground part of the corn plant in the first season potting test.

[0023] Figure 5 It is the influence of the strain NJAU-F2G6 treatment on the stem thickness of the corn plant in the first season potting test.

[0024] Figure 6 It is the influence of the strain NJAU-F2G6 treatment on the dry weight-root of the corn plant in the first season potting test.

[0025] Figure 7 It is the influence of the strain NJAU-F2G6 treatment on the dry weight-above-ground part of the corn plant in the first season potting test.

[0026] Figure 8 It is the influence of the strain NJAU-F2G6 treatment on the corn stalk degradation rate in the second season potting test.

[0027] Figure 9 It is the influence of the strain NJAU-F2G6 treatment on the length of the above-ground part of the corn plant in the second season potting test.

[0028] Figure 10 It is the influence of the strain NJAU-F2G6 treatment on the stem thickness of the corn plant in the second season potting test.

[0029] Figure 11 Effect of the strain NJAU-F2G6 on the dry weight of the above-ground part of the corn plant in the second season potting experiment.

[0030] Figure 12 Effect of the strain NJAU-F2G6 on the corn straw degradation rate in the low-temperature soil incubation experiment.

[0031] In the column chart, ns represents p>0.05, no significant difference; * represents 0.01

[0032] Biological material preservation information

[0033] The strain NJAU-F2G6 is classified as a Cocciidium sp. Epicoccum It is preserved in the China General Microbiological Culture Collection Center, located at No. 1, Beichen West Road, Yard 3, Beijing City, Chaoyang District, Institute of Microbiology of Chinese Academy of Sciences, on March 31, 2025, and the preservation number is CGMCC No. 41876. DETAILED DESCRIPTION

[0034] The application will be further explained in conjunction with the embodiments and the drawings. The following examples are only used to illustrate the application, but not to limit the scope of the application. In the following examples, the test methods are conventional methods unless otherwise specified. In the following examples, the test materials used are purchased from conventional biochemical reagent stores unless otherwise specified.

[0035] Unless otherwise specified, the culture medium and other materials used in the following examples are as follows:

[0036] PDA solid medium (g / L): potato powder 6.0 g, glucose 20.0 g, agar powder 20.0 g. PDA liquid medium removes agar powder.

[0037] Cellulose Congo red medium (g / L): sodium nitrate 1.0 g, disodium hydrogen phosphate 1.2 g, potassium dihydrogen phosphate 0.9 g, magnesium sulfate 0.5 g, potassium chloride 0.5 g, yeast powder 0.5 g, acid hydrolysis casein 0.5 g, Congo red 0.2 g, cellulose powder 5.0 g, agar powder 15.0 g.

[0038] 1 / 2MS liquid medium (g / L): ammonium nitrate 1.0 g, potassium hydrogen phosphate 0.75 g, potassium dihydrogen phosphate 1.5 g, magnesium sulfate heptahydrate 0.05 g, anhydrous calcium chloride 0.005 g, EDTA 0.005 g.

[0039] Corn stalks: corn stalks from Gongzhuling City, Heilongjiang Province, the stems and stalks which are difficult to degrade were selected and dried in an oven at 60°C for 48h.

[0040] The following examples involve culture dishes (plates) with a diameter of 90 mm.

[0041] Example 1 Isolation and screening of functional bacterial strains

[0042] 1. Isolation of bacterial strains:

[0043] The full amount of corn stalks returned to the soil (a), three times the amount of corn stalks returned to the soil (b), five times the amount of corn stalks returned to the soil (c), and no corn stalks returned to the soil (d) were obtained from Harbin City, Heilongjiang Province, for three consecutive years; the full amount of corn stalks returned to the soil (f) and no corn stalks returned to the soil (e) were obtained from Zhaodong City, Heilongjiang Province; the full amount of corn stalks returned to the soil (g) for three consecutive years and the full amount of corn stalks returned to the soil (h) for 11 consecutive years were obtained from Gongzhuling City, Jilin Province.

[0044] The corn stalks were cut into strips about 2-3 cm long, 200g of soil (dry weight) and 2g of corn stalks (dry weight) were added to each treatment, and sterile water was added to 75% of the maximum water holding capacity, a total of eight treatments were cultured at 10°C. The corn stalks from each treatment were taken on the 10th day (referred to as the first batch), the 30th day (referred to as the second batch), and the 120th day (referred to as the third batch) for screening (the present application relates to the second batch). After washing the surface soil of the corn stalks with sterile water (pre-cooled to 10°C), they were placed in 30ml of sterile water (pre-cooled to 10°C), shaken at 200r / min for 1h at room temperature, and allowed to stand for 10min. The supernatant was used as the initial concentration and diluted to 10 -3 ,10 -4 ,10 -5 After three gradients, 0.1ml of bacterial suspension was taken and added to the surface of the cellulose Congo red culture medium for coating culture to screen out potential bacterial strains with straw degradation ability. Each sample was repeated three times, and cultured at 10°C for about 5d. Morphologically different colonies were picked and purified for use, and stored in an ultra-low temperature freezer glycerol tube for future use. The naming method was as follows: the abbreviation of the culture medium (fungi were named F and bacteria were named X in the screening, and the present application relates to fungi) + the sampling batch (the 30th day, i.e. the second batch) + the soil treatment number (capital letters / small letters) + the serial number, for example: F2G6 represents the sixth strain screened from the g soil treatment on the 30th day.

[0045] 2. Primary screening of functional bacterial strains:

[0046] Add 2g (dry weight) of chopped corn stalks (cut into strips approximately 2-3cm long) to each sterile petri dish, to be used for determining the degradation rate of the strain. Randomly selected fungal strains purified from the above-mentioned cellulose Congo red medium were inoculated into PDA liquid culture medium and cultured at 28℃ and 170r / min for 96h. After fermentation, the mycelium was removed by filtration through two layers of gauze. The fermentation broth was adjusted to a spore content ≥5×10⁻⁶ using 1 / 2 MS liquid medium. 6 5 × 10⁻⁶ cells / ml (in this example, it is 5 × 10⁻⁶ cells / ml) 6 Take 10 ml of the sample (each stalk per ml) and add it to the above-mentioned petri dish. Set up a control treatment CK (10 ml of 1 / 2 MS liquid medium was added to the petri dish). Incubate at 10℃ for 15 days. Then, dry the remaining corn stalks in the petri dish in an oven at 60℃ for 48 hours and weigh them to calculate the degradation rate of corn stalks.

[0047] Corn stalk degradation rate = (2g - remaining corn stalk amount (g)) / 2g × 100%

[0048] Thus, strain NJAU-F2G6, which has strong low-temperature degradation function of corn stalks, was obtained, as shown in Table 1 (strains with low corn stalk degradation rate are not listed one by one).

[0049] Table 1. Low-temperature degradation ability of screened strains of corn straw

[0050] Strains Corn stalk degradation rate NJAU-F2G6 5% CK 3% Other representative strains isolated from the same batch 1%

[0051] Example 2 Identification of strain NJAU-F2G6

[0052] After strain NJAU-F2G6 was cultured on PDA solid medium at 28°C for 120 h, as... Figure 1 As shown, the colonies are nearly circular, light yellow to golden yellow / orange, with a lighter, white edge (after 48 hours of incubation, the colonies are entirely white, some with a light yellow center and white edge; as they age, possibly due to the release of yellow or orange pigments, after 120 hours of incubation, the colonies appear light yellow to golden yellow / orange, with a lighter, white edge), and the edges are irregularly petal-shaped and uneven. Figure 2 As shown, the phylogenetic tree alignment analysis based on the 16S rRNA gene sequence of strain NJAU-F2G6 indicates that strain NJAU-F2G6 is related to... Epicoccum layuense NR 158265.1 showed the highest homology, reaching 99.6%. Based on the colony morphology characteristics and phylogenetic tree comparison analysis of the 16S rRNA gene sequence of strain NJAU-F2G6, strain NJAU-F2G6 was identified as a fungus of the genus *Plasmodium*. EpicoccumStrain NJAU-F2G6 has been preserved in China General Microbiological Culture Collection Center, and the preservation number is CGMCC No. 41876.

[0053] Example 3: Study on the effects of strain NJAU-F2G6 on the biomass of corn plants and the degradation rate of corn stalks by pot experiment (first season pot experiment)

[0054] The pot experiment was carried out in the glass greenhouse of Binjiang Campus of Nanjing Agricultural University in Nanjing, Jiangsu Province, from December 2024 to January 2025. The corn variety used in the experiment was a common corn variety (Jinhai No. 5). The corn seeds were sterilized and washed at room temperature, and then germinated in a 30°C incubator in the dark until they were white. The test bacterial agent was NJAU-F2G6 bacterial suspension: after activation, NJAU-F2G6 was added to PDA liquid medium and fermented in a shaker. The fermentation conditions were as follows: fermentation temperature was 28°C, rotation speed was 170 r / min, and fermentation time was 96 h. After fermentation, the mycelium was removed by filtering with two layers of gauze, and the fermentation broth was obtained. The fermentation broth was adjusted with 1 / 2MS liquid medium to obtain NJAU-F2G6 bacterial suspension. The spore content in the NJAU-F2G6 bacterial suspension was ≥5×10 6 6 The dried northeast black soil was mixed with vermiculite and quartz sand (vermiculite:quartz sand volume ratio = 2:1) through a 10-mesh sieve (black soil:vermiculite and quartz sand volume ratio = 6:4) to obtain the soil for the pot experiment. The soil was added to each pot to a depth of 5 cm, and 2 g (dry weight) of cut corn stalks (cut into 2-3 cm long strips) packaged in a 200-mesh bag were added to each pot. Then, 10 ml of 1 / 2MS liquid medium / bacterial agent (NJAU-F2G6 bacterial suspension) was poured on the bag, and then an equal amount of soil was added to each pot to a depth of 10 cm (the volume of the pot was 0.9 L, and the total volume of the soil added was about 750 cm 3 ​The pots were placed in a greenhouse (greenhouse conditions: average temperature of 20°C, air humidity of 80%, 16h light / 8h darkness), and each pot was added with an equal amount of water to completely immerse. On the 5th day, the germinated corn seedlings were transplanted into the pots, 3 corn seedlings per pot, and then watered as needed. On the 30th day after the corn seedlings were transplanted, the corn plants were removed, the above-ground length of the corn plants (the length from the connection between the above-ground part and the underground part to the top of the corn plant), the stem thickness (the thickness of the stem at the connection between the above-ground part and the underground part) were measured, and then the corn plants were cut at the connection between the above-ground part and the underground part with scissors, and the underground part and the above-ground part of the corn plants were separately placed in envelopes and put in an oven at 60°C for 48h, and the dry weight-root and the dry weight-above-ground part of the corn plants were measured, respectively. The net bag containing the corn straw buried in the soil was dug out, the surface soil was washed off with water, the internal corn straw was taken out and placed in a small aluminum box, and the remaining corn straw was dried in an oven at 60°C for 48h before measuring the weight, and the corn straw degradation rate was calculated.

[0055] The pot experiment was set up with 2 treatments, which were: 1) control group (CK), 10ml of 1 / 2MS liquid medium was added; 2) treatment group (F2G6), 10ml of NJAU-F2G6 bacterial suspension was added. Each treatment had 4 replicates (i.e. 4 pots per treatment).

[0056] The corn straw degradation rate results are shown in Table 2. Figure 3 The corn straw degradation rate of the non-inoculated control group was only 8.4%, and the corn straw degradation rate of the NJAU-F2G6 bacterial suspension inoculation treatment group was 9.5%. Compared with the non-inoculated control group, the corn straw degradation rate of the NJAU-F2G6 bacterial suspension inoculation treatment group increased by 13.1%.

[0057] The biomass of each treatment group is shown in Table 3. Figures 4-7 From the above-ground length of the corn plants, the stem thickness, the dry weight-root, and the dry weight-above-ground part, the growth of the corn plants in the NJAU-F2G6 bacterial suspension inoculation treatment group was significantly better than that of the corn plants in the non-inoculated control group.

[0058] Example 4: Verification of the effect of strain NJAU-F2G6 on corn plant biomass and corn straw degradation rate by pot experiment (second season pot experiment)

[0059] The pot experiment was conducted in the glass greenhouse of the Binjiang Campus of Nanjing Agricultural University in Nanjing, Jiangsu Province, from April to May 2025. The tested maize variety was the common maize variety (Jinhai 5). Maize seeds were sterilized and cleaned at room temperature, and then germinated in a 30℃ incubator under shade until they showed signs of germination. The tested inoculum was NJAU-F2G6 bacterial suspension: activated NJAU-F2G6 was added to PDA liquid medium and fermented in a shaker under the following conditions: fermentation temperature 28℃, rotation speed 170 r / min, and fermentation time 96 h. After fermentation, the mycelium was removed by filtration through two layers of gauze to obtain the fermentation broth. The fermentation broth was then adjusted with 1 / 2 MS liquid medium to obtain the NJAU-F2G6 bacterial suspension. The spore content of the NJAU-F2G6 bacterial suspension was ≥5×10⁻⁶. 6 spores / ml (in this example, the spore content in the NJAU-F2G6 bacterial suspension is 5 × 10⁻⁶ spores / ml) 6 (Units / ml). Dry, sieved Northeast black soil was uniformly mixed with vermiculite and quartz sand (volume ratio of vermiculite:quartz sand = 2:1) to obtain soil for pot experiments (volume ratio of black soil:vermiculite:quartz sand = 6:4). Equal amounts of soil were added to each pot to a depth of 5cm. 2g (dry weight) of chopped corn stalks (cut into strips approximately 2-3cm long) packaged in a 200-mesh mesh bag was added to each pot. Then, 10ml of 1 / 2MS liquid culture medium / inoculant (NJAU-F2G6 bacterial suspension) was poured onto the mesh bag as per the treatment instructions. Afterward, equal amounts of soil were added to each pot to a depth of 10cm (pot volume is 0.9L, total soil volume is approximately 750cm³). 3 Place each pot in a greenhouse (average temperature 20℃, air humidity 80%, 16h light / 8h darkness), adding an equal amount of water to each pot until completely saturated. On day 5, transplant the germinated corn seedlings (showing white tips) into the pots, planting 2 seedlings per pot. Then, supplement with an equal amount of 1 / 2 MS liquid culture medium as needed. On day 30 after transplanting, remove the corn plants and measure the aboveground length (length from the junction of the aboveground and underground parts to the top of the plant) and stem diameter (thickness of the stem at the junction of the aboveground and underground parts). Then, cut the corn plants at the junction of the aboveground and underground parts with scissors, place the aboveground parts of the plants separately in an envelope, and place them in a 60℃ oven for 48 hours. Measure the dry weight of the aboveground parts. The net bags containing corn stalks buried in the soil were dug up, the surface soil was washed away with water, the corn stalks inside were taken out and placed in a small aluminum box, and then dried in an oven at 60℃ for 48 hours. The weight of the remaining corn stalks was measured and the degradation rate of the corn stalks was calculated.

[0060] The pot experiment consisted of two treatments: 1) control group (CK), which received 10 ml of 1 / 2 MS liquid medium; and 2) treatment group (F2G6), which received 10 ml of NJAU-F2G6 bacterial suspension. Each treatment was replicated four times (i.e., four pots per treatment).

[0061] The results of corn stalk degradation rate are as follows Figure 8 As shown, the degradation rate of corn stalks in the uninoculated control group was only 9.9%, while the degradation rate in the group inoculated with NJAU-F2G6 bacterial suspension was 15.3%. Compared with the uninoculated control group, the degradation rate of corn stalks in the group inoculated with NJAU-F2G6 bacterial suspension increased by 54.5%, and the overall trend was consistent with the results of the first pot experiment (Example 3), further verifying the excellent ability of the NJAU-F2G6 strain to promote the degradation of corn stalks.

[0062] Biomass of each treatment such as Figures 9-11 As shown, in terms of aboveground length, stem diameter, and dry weight minus aboveground part, the maize plants in the NJAU-F2G6 bacterial suspension treatment group showed significantly better growth than the control group without the inoculum. This result is consistent with the results of the first season pot experiment (Example 3), further verifying the excellent growth-promoting effect of the NJAU-F2G6 strain on maize plants while promoting the degradation of maize straw.

[0063] Two pot experiments effectively demonstrated the excellent ability of strain NJAU-F2G6 to promote the degradation of corn stalks, and its excellent effect on promoting corn plant growth while simultaneously promoting stalk degradation. The difficulty in degrading corn stalks when returning them to the field in Northeast China is one of the reasons affecting stalk return. This invention provides strain resources and technical support for enhancing the low-temperature degradation of stalks while promoting crop growth.

[0064] Example 5: Low-temperature soil preparation experiment was used to further verify the effect of strain NJAU-F2G6 on the degradation rate of corn straw.

[0065] The low-temperature soil cultivation experiment was conducted in a low-temperature constant-temperature incubator (PHCbi brand) in the laboratory of Nanjing Agricultural University, Binjiang Campus, Nanjing City, Jiangsu Province, from March to May 2025. The test inoculum was NJAU-F2G6 bacterial suspension: activated NJAU-F2G6 was added to PDA liquid medium and cultured at 28℃ on a shaker at 170 r / min for 96 h. After fermentation, the mycelium was removed by filtration through two layers of gauze to obtain the fermentation broth. The fermentation broth was adjusted with 1 / 2 MS liquid medium to obtain the NJAU-F2G6 bacterial suspension. The spore content of the NJAU-F2G6 bacterial suspension was ≥5×10⁻⁶. 6 spores / ml (in this example, the spore content in the NJAU-F2G6 bacterial suspension is 5 × 10⁻⁶ spores / ml) 6ml size of tissue culture bottles, each of which was added a portion of dried and 10 mesh sieved northeast black soil, 2 g (dry weight) of cut corn straw (cut into 2-3 cm long strips) was added to each bottle, and 10 ml of 1 / 2MS liquid medium / agent (NJAU-F2G6 bacterial suspension) was poured on the bag, and the remaining soil was buried in the bag (the total amount of soil added to each tissue culture bottle was 160 g of dry weight). After 70 days of incubation at 10°C, the soil moisture content was maintained at 70% of the maximum water holding capacity of the soil by regular watering. After incubation, the bags containing corn straw buried in the soil were removed, washed with water to remove the surface soil, and the internal corn straw was removed and placed in a small aluminum box. The remaining corn straw was dried in an oven at 60°C for 48 h, and the weight of the remaining corn straw was measured to calculate the corn straw degradation rate.

[0066] Low temperature incubation soil test was set up with 2 treatments, namely 1) control group (CK), adding 1 / 2MS medium 10 ml; 2) treatment group (F2G6), adding NJAU-F2G6 bacterial suspension 10 ml. Each treatment was repeated 3 times (i.e. 3 tissue culture bottles for each treatment).

[0067] The corn straw degradation rate results are shown in Table 1. Figure 12 The corn straw degradation rate of the non-inoculated control group was only 8.3%, while the corn straw degradation rate of the NJAU-F2G6 bacterial suspension inoculation treatment group was 17.2%. Compared with the non-inoculated control group, the corn straw degradation rate of the NJAU-F2G6 bacterial suspension inoculation treatment group increased by 107.2%, further verifying the ability of NJAU-F2G6 strain to promote corn straw degradation under low temperature conditions (10°C).

Claims

1. A strain of *Pseudomonas* fungus, NJAU-F2G6, which is a low-temperature straw-degrading bacterium, was taxonomically named *Pseudomonas*. Epicoccum sp., deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 31, 2025, with accession number CGMCC No. 41876.

2. The inoculum prepared by the low-temperature straw-degrading fungus NJAU-F2G6 as described in claim 1.

3. The microbial agent according to claim 2, characterized in that, The microbial agent is prepared by the following method: liquid fermentation of *Plasmodium* fungus NJAU-F2G6 with preservation number CGMCC No.41876 is carried out. After fermentation, the mycelium is removed by filtration to obtain fermentation broth. The spore content of the fermentation broth is adjusted to obtain a microbial suspension, which is the microbial agent.

4. The microbial agent according to claim 3, characterized in that, The microbial agent is prepared by the following method: *Plasmodium* fungus NJAU-F2G6 (CGMCC No. 41876) is inoculated into a first liquid culture medium for liquid fermentation. The first liquid culture medium includes PDA liquid medium. The liquid fermentation conditions are: fermentation temperature 28-30℃, rotation speed 170-190 r / min, and fermentation time 96-120 h. After fermentation, the mycelium is removed by filtration through multiple layers of gauze to obtain the fermentation broth. The spore content of the fermentation broth is adjusted using a second liquid culture medium to obtain a microbial suspension, which is the microbial agent. The second liquid culture medium includes 1 / 2 MS liquid medium. The spore content of the microbial suspension is ≥5 × 10⁻⁶. 6 per ml.

5. The application of the low-temperature straw-degrading fungus NJAU-F2G6 described in claim 1 in low-temperature straw degradation and crop growth promotion, characterized in that, The crop is corn; the straw is corn stalks.

6. The application of the microbial agent according to any one of claims 2-4 in low-temperature straw degradation and crop growth promotion, characterized in that, The crop is corn; the straw is corn stalks.

Images