Soil enterobacter capable of efficiently degrading polypropylene and application of soil enterobacter

Abstract

The invention discloses soil enterobacter capable of efficiently degrading polypropylene and application of the soil enterobacter. The bacterium is a strain FJNUIM-S2, is classified and named as Enterobacter soli, and is preserved in the China General Microbiological Culture Collection Center (CGMCC), the preservation time is October 17, 2024, the preservation number is CGMCC No.32241, and the preservation address is Institute of Microbiology, Chinese Academy of Sciences, No.3, No.1 Yard, West Beichen Road, Chaoyang District, Beijing. The strain FJNUIM-S2 disclosed by the invention can grow by taking polypropylene as a unique carbon source, has a good polypropylene degradation characteristic, provides a microbial resource for bioremediation of waste polypropylene in the environment, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to a soil enterobacterium capable of efficiently degrading polypropylene and application thereof. Background Art

[0002] Plastic products are widely used in various fields due to their low production cost and good durability. With the development of the plastics industry and the widespread use and consumption of plastic products, more and more waste petroleum-based plastic products are entering the environment. Conventional physical and chemical methods for treating plastic waste have limitations such as high cost, many by-products and secondary pollution. "White pollution" has become a global problem. The consumption of polyethylene (PE), polypropylene (PP) and polystyrene (PS) plastics accounts for 50% of the total synthetic plastics and is the main component of plastic waste. Polypropylene is widely used in masks, packaging and packaging boxes, etc., accounting for 18.9% of the global plastic production in 2022, making it the second largest plastic in terms of production after polyethylene. Moreover, polypropylene is more chemically inert than polyethylene and is more difficult to degrade.

[0003] The recycling technology of waste polypropylene is single, the added value of recycled products is low, and the value of reuse is not reflected. Waste plastics in the environment have caused serious damage to the ecosystem. The formation of small-sized microplastics and nanoplastics under abiotic or biotic factors endangers the health of animals, plants and humans. Incineration will produce harmful gases, and landfill treatment has a long degradation cycle, which seriously affects the soil ecological environment. At present, there is an urgent need for an environmentally friendly, efficient and simple degradation method to alleviate the global pollution problem caused by polypropylene plastics, and microbial degradation of plastics has therefore attracted much attention.

[0004] Among the reported microorganisms with the ability to degrade plastics, most are concentrated on polyethylene (PE) and polyethylene terephthalate (PET). Among them, the bacteria mainly include Pseudomonas and Bacillus, and the fungi mainly include Aspergillus and Fusarium. The microorganisms with high degradation performance for plastics mainly include: Balasubramanian et al. screened out Pseudomonas sp. GMB7 and Arthrobacter sp. GMB5 that can efficiently degrade high-density polyethylene (HDPE), with a weight loss of 15% and 12% respectively after incubation for 30 days (Balasubramanian V, Natarajan K, Hemambika B, et al. High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India. Lett Appl Microbiol 2010, 51(2): 205-211.); Elsamahy et al. constructed Sterigmatomyces halophilus SSA1575, Meyerozyma guilliermondii SSA1547 and Meyerozyma caribbica isolated from the intestine of termites. SSA1654 yeast colony, which caused a 63.4% reduction in tensile strength and a 33.2% reduction in net low-density polyethylene (LDPE) mass (Elsamahy T, Sun J, Elsilk SE, et al. Biodegradation of low-density polyethylene plastic waste by a constructed tri-culture yeast consortium from wood-feeding termite: Degradation mechanism and pathway. Hazard Mater 2023, 448: 130944.); Auta et al. found that Bacillus cereus and Bacillus gottheilii lost 6.6% and 3.0% of PET weight respectively after 40 days of shake flask experiment (Auta HS, Emenike CU, Fauziah SH.Screening of Bacillus strains isolated from mangrove ecosystems in Peninsular Malaysia for microplastic degradation. Environ Pollut 2017, 231 (Pt 2): 1552-1559.); Das et al. screened out two bacterial strains, Pseudomonas aeruginosa NBTU01 and Achromobacter sp. NBTU02, with degradation rates of 35.65% and 34.63% for PVC in 180 days, respectively (Das G, Bordoloi NK, Rai SK, et al. Biodegradable and biocompatible epoxidized vegetable oil modified thermostable poly (vinyl chloride): thermal and performance characteristics post biodegradation with Pseudomonas aeruginosa and Achromobacter sp. Hazard Mater 2012, 209-210: 434-442.); Ganesh et al. screened out a strain of Bacillus paralicheniformis G1 degraded 34% of PS membrane within 60 days (Ganesh Kumar A, Hinduja M, Sujitha K, et al. Biodegradation of polystyrene by deep-sea Bacillus paralicheniformis G1 and genome analysis. Science Total Environ 2021, 774: 145002.); Jeon et al. screened out the bacteria Stenotrophomonas panacihumi PA3-2, which degraded LMWPP-1 (Mn: 2,800, Mw: 10,300) by 20.3 ± 1.39% and LMWPP2 (Mn: 3,600, Mw: 19,700) by 16.6 ± 1.70% after 90 days of composting (Jeon HJ, Kim MN. Isolation of mesophilic bacterium for biodegradation of polypropylene.International Biodeterioration&Biodegradation 2016, 115: 244-249.); Skariyachan et al. isolated 8 strains of plastic degrading bacteria, among which the combined flora of Aneurinibacillus aneurinilyticus btDSCE01, Brevibacillus agri btDSCE02, Brevibacillus sp. btDSCE03 and Brevibacillus brevis btDSCE04 had the highest degradation rate and was higher than that of the individual flora. The degradation rate of PP particles was as high as 56.3±2% after 140 days of cultivation at 50°C (Skariyachan S, Patil AA, Shankar A, et al. Enhanced polymer degradation of polyethylene and polypropylene by novel thermophilic consortia of Brevibacillus sps. and Aneurinibacillus sp. screened from waste management landfills and sewage treatment plants. Polymer Degradation and Stability 2018, 149: 52-68.). These strains with degradation properties reflect the good prospects of biodegradable plastics and lay the foundation for the possible degradation mechanism of efficient degradation strains and the exploration of efficient degradation enzymes.

[0005] However, there are currently very few reports on the biodegradation of polypropylene plastics, and there is a serious lack of polypropylene plastic-degrading strains that can be studied and applied. Therefore, finding effective microbial and enzyme resources for biodegrading polypropylene plastics, enriching the degradation strain resource library, and developing and improving the green recycling process for biodegrading polypropylene are of great significance to the environmental pollution caused by polypropylene plastics. Summary of the invention

[0006] The invention aims at providing a soil enterobacterium capable of efficiently degrading polypropylene and application thereof.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The present invention first provides a strain FJNUIM-S2 for efficiently degrading polypropylene, which is classified and named as soil Enterobacter soli, and is deposited in the General Microbiology Center (CGMCC) of the China Microbiological Culture Collection Administration. The deposit time is October 17, 2024, the deposit number is CGMCC No. 32241, and the deposit address is the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0009] The nucleotide sequence of 16S rDNA of the strain FJNUIM-S2 is shown in SEQ ID No.1.

[0010] The strain FJNUIM-S2 can be used for biodegrading polypropylene, especially polypropylene plastic, including polypropylene plastic film, granules or powder.

[0011] The present invention also provides the use of the strain FJNUIM-S2 in preparing a degradation bacterial agent for degrading polypropylene.

[0012] The present invention also provides a polypropylene degradation bacterial agent produced by strain FJNUIM-S2, and the preparation method thereof comprises the following steps:

[0013] (1) The strain FJNUIM-S2 was streaked and isolated on an LB plate, and after activation, a single clone was picked and inoculated into a test tube containing LB liquid medium, and cultured until the exponential growth phase as a primary seed solution; then, an inoculum amount of not less than 0.5% (v / v) was inoculated into LB liquid medium, and shaken and cultured until the exponential growth phase to obtain a seed solution for fermentation;

[0014] (2) inoculating the fermentation seed solution into the culture medium of the seed tank at an inoculation rate of 5-20% (v / v), and culturing until the exponential growth phase to obtain the secondary seed solution;

[0015] (3) The secondary seed liquid is inoculated into the culture medium of the production tank at an inoculation amount of not less than 0.2% (v / v) and cultured and fermented for 8-12 hours. During the culture process, the pH is adjusted online to about 7.0, the ventilation volume of sterile air is 1-2vvm, the stirring rate is 200-400rpm, and the culture temperature is 30-37°C. After the fermentation is completed, the culture liquid is directly packaged into liquid degradation bacteria agent, or the bacteria are dried to form powder, or prepared into a high-purity preparation through separation and purification steps. The culture medium of the seed tank is LB culture medium, and the culture medium of the production tank is polypropylene powder (film) only carbon source culture medium.

[0016] The polypropylene degradation bacterial agent can be used for biodegrading polypropylene plastics, and the polypropylene plastics are polypropylene plastic wastes existing in landfills or water bodies.

[0017] The present invention also provides a method for polypropylene degradation, which comprises culturing the strain FJNUIM-S2 or the polypropylene degradation bacterial agent as claimed in claim 1, and contacting the polypropylene plastic to be degraded with the strain culture or the degradation bacterial agent.

[0018] Compared with the prior art, the polypropylene efficient degradation strain FJNUIM-S2 obtained by separation and screening in the present invention can be used for microbial degradation of polypropylene, especially polypropylene film, granules, and powdered polypropylene plastics discarded in the environment. The strain FJNUIM-S2 of the present invention can grow with polypropylene as the only carbon source, has good polypropylene degradation characteristics, provides microbial resources for the bioremediation of discarded polypropylene in the environment, and has broad application prospects.

[0019] The strain FJNUIM-S2 of the present invention has a very good polypropylene degradation ability, especially a significant degradation effect on polypropylene film. After 60 days of treatment for polypropylene plastic degradation, the surface of the polypropylene film becomes obviously rough, with obvious holes, gullies and grooves, and the surface is seriously damaged. The weight loss of the degraded polypropylene film before and after degradation can reach about 0.5 mg; and the thermal decomposition temperature of the degraded polypropylene film is reduced, and the thermal stability is deteriorated. The degradation is green and environmentally friendly, the degradation cost is low, and the operation is simple and convenient.

[0020] The degradation bacterial agent of the present invention can be produced using fermentation equipment commonly used in the fermentation industry, has the advantages of good degradation effect, low production cost, easy operation, etc., is suitable for treating difficult-to-degrade waste polypropylene in the environment, and has positive significance in protecting the ecological environment and maintaining human health. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the single colony morphology of the plate dilution spread of strain FJNUIM-S2.

[0022] Figure 2 The phylogenetic tree was constructed based on 16S rRNA sequences, in which strain FJNUIM-S2 was used Annotation.

[0023] Figure 3 This is the growth curve of soil Enterobacter FJNUIM-S2 with polypropylene as the only carbon source.

[0024] Figure 4 The surface microscopic features of polypropylene membrane before and after degradation under scanning electron microscope. (A) Control group (no inoculation); (B) Polypropylene membrane degraded by soil Enterobacter FJNUIM-S2.

[0025] Figure 5 It is the Fourier transform infrared spectroscopy analysis of polypropylene film before and after degradation.

[0026] Figure 6 It is the thermogravimetric analysis of polypropylene film before and after degradation. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0028] Unless otherwise specified, the raw materials and reagents in the present invention are commercially available.

[0029] Example 1 Isolation, screening and identification of strain FJNUIM-S2

[0030] 1. Isolation and screening of polypropylene-degrading bacteria

[0031] 1.1 Sample collection: The soil samples were collected from the Wengcuoshan landfill (old site) in Minhou County, Fujian Province. The collection depth was 3-10 cm. The collected soil samples were placed in sterile triangular bottles and brought back to the laboratory for use.

[0032] 1.2 Experimental culture medium

[0033] (1) LB medium: 10 g / L tryptone, 5 g / L yeast extract, 10 g / L NaCl, 15-20 g / L agar powder for solid medium, add double distilled water to 1000 mL, adjust pH to 7.2 with 5 mol / L NaOH, and sterilize at 121°C for 30 min.

[0034] (2) 10× trace element mother solution: weigh 10 g FeSO4·7H2O, 10 g MgSO4·7H2O, 1 g MnSO4·H2O, 1 g ZnSO4·7H2O, and 1 g CuSO4·5H2O into 800 mL of double distilled water, stir until completely dissolved, then make up to 1000 mL and filter through a 0.22 μm filter to sterilize.

[0035] (3) Trace carbon source medium: Weigh 0.5 g yeast extract, 2 g (NH4)2SO4, and 4.5 g polypropylene powder into 800 mL of double distilled water, stir until completely dissolved, then dilute to 900 mL, and sterilize at 121°C for 15 min. After cooling, add 100 mL of 10× trace element stock solution.

[0036] (4) Polypropylene powder as the sole carbon source culture medium: Weigh 2 g (NH4)2SO4 and 5 g polypropylene powder into 800 mL of double distilled water, stir until completely dissolved, then adjust the volume to 900 mL, sterilize at 121°C for 15 min. After cooling, add 100 mL of 10× trace element stock solution.

[0037] (5) Polypropylene membrane sole carbon source culture medium: Weigh 0.1 g (NH4)2SO4 into 40 mL of double distilled water, stir until completely dissolved, then dilute to 45 mL, sterilize at 121°C for 15 min. After cooling, add pretreated polypropylene membrane and 5 mL of 10× trace element stock solution.

[0038] 1.3 Isolation of strains

[0039] Add 2g of the collected soil sample to 50mL of trace carbon source medium, and culture the trace carbon source medium without inoculation of the sample under the same conditions as a blank control, 37℃, 180rpm culture for 6 days, centrifuge at 4℃, 5000rpm to collect the culture bacteria, transfer the centrifuged bacterial precipitate to a new 50mL trace carbon source medium and continue to culture for 6 days. Collect the culture bacteria by centrifugation at 4℃, 5000rpm, transfer to 50mL of polypropylene powder as the only carbon source medium, and culture the polypropylene powder as the only carbon source medium without inoculation of bacterial precipitate under the same conditions as a blank control, 37℃, 180rpm culture for 10 days. Collect the culture bacteria by centrifugation at 4℃, 5000rpm, add 200μL of physiological saline to resuspend the bacteria, apply it on LB solid medium, and culture at 37℃ for 12-24h. After the colonies grow, pick colonies with different morphologies and inoculate them on LB solid medium plates, and repeatedly streak and separate until a single colony is obtained. After a single colony grows out, it is transferred to a new LB test tube slant medium for storage to obtain the purified strain FJNUIM-S2. Meanwhile, the liquid cultured bacterial solution is stored in LB medium containing 30% glycerol at -80°C for future use.

[0040] 1.4 DNA extraction and PCR amplification of strains

[0041] 5 mL of bacterial culture cultured overnight at 37°C was collected and DNA was extracted according to the operation steps of the bacterial genomic DNA extraction kit (Nanjing Novozyme Biotechnology Co., Ltd., Catalog No.: DC103-01). The extracted bacterial DNA was stored in a -20°C refrigerator for future use. The extracted genome was used as a template to amplify bacterial 16S rRNA using universal primers 27F and 1492R (primers 27F: 5'-AG AGTTTGATCCTGGCTCAG-3' and 1492R: 5'-TACGGCTACCTTGTTACGACTT-3' were synthesized by Beijing Qingke Biotechnology Co., Ltd.). The PCR amplification reaction system was a 20 μL system: 1 μL DNA template, 0.8 μL of primers 27F and 1492R (10 μM), 10 μL of 2×Phanta Max Master Mix (Nanjing Novozyme Biotechnology Co., Ltd., Catalog No.: P515-01), and ddH2O was added to a total volume of 20 μL. The PCR reaction conditions were as follows: 95°C pre-denaturation for 5 min; 95°C denaturation for 30 s, 56°C annealing for 30 s, 72°C extension for 1 min, for a total of 30 cycles; 72°C extension for another 5 min, and storage at 4°C. The qualified PCR products were sent to Fuzhou Qingke Biotechnology Co., Ltd. for sequencing.

[0042] 2 Identification of strains

[0043] After the purified strain FJNUIM-S2 was inoculated into LB solid medium and cultured at 37°C for 1 day (3 replicates), the colony morphology was described, and the microscopic morphology was measured and described after slide preparation, as follows:

[0044] Morphological description of strain FJNUIM-S2: The bacteria were cultured on LB solid medium for 1 day and their morphology was observed and data was recorded. The colony morphology was round, the colony size was 1-2 mm, the front was white, opaque, the edges were neat, the middle was raised, the surface was smooth, and the texture was moist ( Figure 1 ).

[0045] The purified strain FJNUIM-S2 was inoculated into LB liquid culture medium and cultured at 37°C and 180 rpm until the exponential growth phase. Gram staining was performed. Under an optical microscope, it was observed that the strain was red after Gram staining, indicating that it was a Gram-negative bacterium.

[0046] Based on the 16S rRNA sequence, the sequence with high similarity to strain FJNUIM-S2 was downloaded, and the strain and the downloaded sequence were compared using ClustalX2 software. The phylogenetic tree of strain FJNUIM-S2 and related strains was constructed using the maximum likelihood method with Bacillus sp. Strain A6 as the outgroup using MEGA11 software. The results showed that the strain sequence was well clustered with the sequence of Enterobacter ( Figure 2 ). The results of 16S rRNA sequence BLASTn comparison showed that the similarity between strain FJNUIM-S2 and Enterobacter soli was as high as 99.93%. Based on the morphological characteristics and molecular biological experimental data, strain FJNUIM-S2 was identified as soil Enterobacter soli.

[0047] The soil Enterobacter soli FJNUIM-S2 (Enterobacter soli FJNUIM-S2) of the present invention is deposited in the General Microbiology Center (CGMCC) of the China Microbiological Culture Collection Administration, the deposit time is October 17, 2024, the deposit number is CGMCC No.32241, and the deposit address is the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0048] 3. Preservation and subculture of bacterial strains:

[0049] The soil Enterobacter FJNUIM-S2 strain was streaked and activated on a LB solid medium plate, incubated at 37°C for 1 day, and then a single colony was picked and inoculated into LB liquid medium, and cultured at 37°C, 180rpm overnight. Under sterile conditions, the culture was aspirated and added to a sterilized 30% glycerol cryopreservation tube, 3 tubes were stored in a -20°C refrigerator, and 3 tubes were stored in a -80°C ultra-low temperature refrigerator, and the survival of the strain was checked regularly.

[0050] Example 2 Experiment on degradation of polypropylene powder by soil Enterobacter strains

[0051] In order to evaluate the degradation ability of polypropylene-degrading bacteria on waste polypropylene plastics in the environment, polypropylene powder was selected as the only carbon source and energy culture medium to determine the growth curve of the degradation microorganisms:

[0052] Inoculate soil Enterobacter FJNUIM-S2 at a 2% inoculation rate into the culture medium with polypropylene powder as the sole carbon source and mix well. Use the polypropylene powder as the sole carbon source without inoculation of bacteria as the control. Use the control group as the blank for zero adjustment and measure the initial OD 600 Culture at 37°C, 180 rpm, and measure OD at fixed points every 3 days 600The growth curve of the strain in the culture medium with polypropylene as the sole carbon source was drawn. The growth curve shows that when the soil Enterobacter FJNUIM-S2 grew on the culture medium with polypropylene powder as the sole carbon source, it was in the lag phase for the first 9 days, entered the exponential growth phase on the 9th day, and continued until the 18th day when it entered the stable phase ( Figure 3 ).

[0053] Example 3 Experiment on degradation of polypropylene film by soil Enterobacter strains

[0054] 1.1 Determination of weight loss of polypropylene film

[0055] The polypropylene film with a thickness of 0.3 mm was cut into 1.5×1.5 cm, soaked in 2% SDS for 4 hours, ultrasonically cleaned for 30 minutes, and then moved into the clean bench. After soaking in 75% alcohol for 4 hours, it was rinsed 3 times with sterile double distilled water, and naturally air-dried in the clean bench. The initial weight was weighed and recorded with a 1 / 10,000 balance, and the corresponding polypropylene film sole carbon source culture medium was prepared after marking the number. The soil Enterobacter FJNUIM-S2 was inoculated into the polypropylene film sole carbon source culture medium with an inoculation rate of 2%. Each strain was paralleled in three groups, and the polypropylene film sole carbon source culture medium without inoculation of strains was used as a control. The flask was shaken for 60 days at 37°C and 100rpm. After the shake flask culture was completed, the polypropylene film was taken out and the weight of the remaining polypropylene film after degradation was weighed on a 1 / 10,000 balance. The weight loss of the polypropylene film degraded by the soil Enterobacter FJNUIM-S2 strain before and after degradation can reach about 0.5 mg.

[0056] 1.2 Scanning electron microscope observation of the surface of polypropylene film

[0057] Cut the degraded polypropylene film into a 2mm×2mm size at the center, spray gold twice, and observe on the machine. Find the sample under the low-power microscope, then switch to high-power mode, manually adjust the brightness and contrast, and scan slowly after the sample morphology is clear. After determining the required sample morphology, take a picture and save it. Spray gold twice on the degraded polypropylene film and observe on the machine. Compared with the control group (no inoculation), the surface of the polypropylene film degraded by soil Enterobacter FJNUIM-S2 became obviously rough, with obvious holes, gullies and grooves, and the degree of damage was large ( Figure 4 ).

[0058] 1.3 Fourier transform infrared spectroscopy detection of polypropylene film

[0059] Cut the degraded polypropylene film into small pieces and mark them for later use. Wipe the sample slide, medicine spoon, ground agate, etc. with alcohol cotton and put them in an oven to dry. Take the sample to be tested and potassium bromide powder and grind them in the ground agate at a ratio of 1:50. Load the ground mixture into the sample slide, then put it on the tablet press and tighten it slightly. Adjust the pressure to 1.5 and wait for a while before loosening it. Take out the sample slide and put it in the middle of the infrared cavity. Then use Fourier transform infrared spectroscopy analysis to collect sample data. The control groups include PP (untreated polypropylene film) and PP / shaking (polypropylene film without inoculation of bacteria). The PP / shaking sample is at ~1635cm -1 and ~3448cm -1 There is a clear absorption peak, which is considered to be the result of the trace elements in the culture medium being firmly adsorbed on the polypropylene during the shaking process and cannot be washed off. The polypropylene film degraded by soil Enterobacter FJNUIM-S2 is at ~3435cm -1 The characteristic peak absorption intensity of hydroxyl (-OH) at Figure 5 ), it was speculated that the polypropylene film degraded by soil Enterobacter FJNUIM-S2 might have undergone hydroxylation reaction.

[0060] 1.4 Thermogravimetric testing of polypropylene film

[0061] Cut the degraded polypropylene film into 2mm×2mm size, weigh 5-10mg, and dry it at 85℃ for 4 hours for later use. After loading the sample, place the crucible on the tray, and start the thermogravimetric test after ensuring that the tray is stable. The thermogravimetric curve of the polypropylene film degraded by soil Enterobacter FJNUIM-S2 showed a significant left shift compared with the control group (PP: untreated polypropylene film; PP / shaking: polypropylene film without inoculation of bacteria) ( Figure 6 ), indicating that the thermal decomposition temperature of the degraded polypropylene film decreased and its thermal stability became worse; indicating that soil Enterobacter FJNUIM-S2 can destroy the molecular structure of the polypropylene film and reduce its thermal stability.

[0062] Example 4 Preparation of a degradation agent based on soil Enterobacter FJNUIM-S2

[0063] (1) Streaking and activating the strain FJNUIM-S2 on an LB solid medium plate, picking a single clone and inoculating it into a test tube containing LB liquid medium, and culturing it until the exponential growth phase as a primary seed solution; then inoculating it into LB liquid medium at an inoculum amount of not less than 0.5% (v / v), shaking and culturing it until the exponential growth phase, and obtaining a seed solution for fermentation;

[0064] (2) inoculating the fermentation seed solution into the culture medium of the seed tank at an inoculation rate of 5-20% (v / v), and culturing until the exponential growth phase to obtain the secondary seed solution;

[0065] (3) The secondary seed liquid is inoculated into the culture medium of the production tank at an inoculation amount of not less than 0.2% (v / v) and cultured and fermented for 8-12 hours. During the culture process, the pH is adjusted online to about 7.0, the ventilation volume of sterile air is 1-2vvm, the stirring rate is 200-400rpm, and the culture temperature is 30-37°C. After the fermentation is completed, the culture liquid is directly packaged into liquid degradation bacteria agent, or the bacteria are dried to form powder, or prepared into a high-purity preparation through separation and purification steps. The culture medium of the seed tank is LB culture medium, and the culture medium of the production tank is polypropylene powder (film) only carbon source culture medium.

[0066] The bacterial agent prepared in Example 4 of the present invention can directly react with polypropylene plastic films, particles or powders to effectively degrade polypropylene plastics to achieve the effects of Examples 2 and 3.

[0067] The above results show that soil Enterobacter FJNUIM-S2 has a good effect in degrading polypropylene plastic without pretreatment.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A strain FJNUIM-S2 that efficiently degrades polypropylene, characterized in that: Its classification is named as soil Enterobacter Enterobacter soli ), deposited in the General Microbiology Center of China Microorganism Culture Collection (CGMCC), the deposit date is October 17, 2024, the deposit number is CGMCC No.32241, and the deposit address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

2. Use of the strain FJNUIM-S2 as claimed in claim 1 in biodegradation of polypropylene.

3. The use according to claim 2, characterized in that: The polypropylene includes polypropylene plastic film, particles or powder.

4. Use of the strain FJNUIM-S2 as claimed in claim 1 in preparing a degradation bacterial agent for degrading polypropylene.

5. A polypropylene degrading bacterial agent produced using the strain FJNUIM-S2 described in claim 1.

6. The method for preparing the polypropylene degradation bacterial agent according to claim 5, characterized in that: The following steps are involved: (1) The strain FJNUIM-S2 described in claim 1 is streaked and isolated on an LB plate, and after activation, a single clone is picked and inoculated into a test tube containing LB liquid culture medium, and cultured until the exponential growth phase as a primary seed liquid; then, an inoculum amount of not less than 0.5% (v / v) is inoculated into LB liquid culture medium, and shaken and cultured until the exponential growth phase to obtain a seed liquid for fermentation; (2) Inoculate the fermentation seed solution into the culture medium of the seed tank at an inoculation rate of 5-20% (v / v), and culture until the exponential growth phase to obtain the secondary seed solution; (3) The secondary seed liquid is inoculated into the culture medium of the production tank at an inoculation rate of not less than 0.2% (v / v) and cultured and fermented for 8-12 hours. During the culture process, the pH is adjusted online to about 7.0, the ventilation volume of sterile air is 1-2 vvm, the stirring rate is 200-400 rpm, and the culture temperature is 30-37°C. After the fermentation is completed, the culture liquid is removed from the tank and packaged to obtain a liquid degradation bacterial agent.

7. The method for preparing the polypropylene degradation bacterial agent according to claim 6, characterized in that: The culture solution after fermentation in step (3) is dried to prepare a powder, or prepared into a high-purity preparation by separation and purification.

8. Use of the polypropylene degrading bacterial agent as claimed in claim 5 in biodegrading polypropylene plastics.

9. The use according to claim 8, characterized in that: The polypropylene plastic is polypropylene plastic waste existing in landfills or water bodies.

10. A method for polypropylene degradation, characterized in that: The method comprises culturing the strain FJNUIM-S2 as claimed in claim 1 or the polypropylene degradation bacterial agent as claimed in claim 5, and contacting the polypropylene plastic to be degraded with the strain culture or the degradation bacterial agent.

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