Arthrinium subsporum as well as fungicide and application of arthrinium subsporum

Abstract

The invention belongs to the field of microorganisms, and provides arthrinium phaeospermum as well as a fungicide and application thereof, the arthrinium phaeospermum is arthrinium phaeospermum LF-2024, is preserved in Guangdong Microbiological Culture Collection Center, has a preservation number of GDMCC No: 65948, can grow by taking polylactic acid plastic as a unique carbon source, has a good degradation effect on the polylactic acid plastic, and can be applied to the field of biodegradation of the polylactic acid plastic. The strain can be used as an active component for preparing a bacterial agent for degrading polylactic acid plastic, is applied to biodegradation of polylactic acid plastic waste, and has a good application prospect and ecological environmental protection value.

Description

Technical Field

[0001] The present invention relates to the field of microorganisms and also to the field of plastic degradation, and in particular to a dark spore arthrosporum fungus and a bacterial agent and application thereof. Background Art

[0002] With the development of the chemical industry, plastic products are widely used in various packaging materials due to their lightness, durability, cheapness and convenience. Polylactic acid (PLA) is a polymer material made from lactic acid monomers. It has the advantages of biodegradability and renewability and is widely used in packaging, medical and agricultural fields. However, the global plastic pollution problem is becoming increasingly serious. Although PLA is biodegradable, its degradation rate is slow. It is still necessary to find efficient and green ways to solve the pollution problem of PLA plastics.

[0003] At present, the most widely used methods for PLA plastic pollution control include photodegradable plastics, chemical pyrolysis degradation and microbial degradation. Microorganisms are of various types and have strong decomposition and metabolism capabilities. They are important promoters of material circulation in the ecological environment. Therefore, in recent years, microbial degradation has become the mainstream due to its advantages such as low cost, low energy consumption and less negative impact on the environment. Microbial remediation can make up for the shortcomings of physical and chemical remediation technologies. It uses the characteristics of PLA degrading bacteria to use PLA as a carbon source and energy source to achieve the purpose of eliminating pollution and restoring ecological balance. It is a green, economical and promising PLA degradation technology. However, the number of strains with PLA plastic degradation function discovered so far is relatively small, and the degradation effect is limited. Therefore, it is of great significance to screen and cultivate strains with PLA plastic degradation ability. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a dark spore arthroncus and its bacterial agent and application. The dark spore arthroncus can grow with polylactic acid as the only carbon source and has a good effect on the degradation of polylactic acid.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, the present invention provides a kind of Arthrinium phaeospermum, which is Arthrinium phaeospermum LF-2024, which is deposited in Guangdong Microbiological Culture Collection Center with a deposit number of GDMCC No: 65948.

[0007] In a second aspect, the present invention provides the use of the above-mentioned Arthrosporum fusobacteria in degrading polylactic acid plastics.

[0008] According to the above solution, the polylactic acid plastic is polylactic acid plastic powder, granules or film.

[0009] According to the above scheme, the dark spore arthroncus uses polylactic acid plastic as the only carbon source to degrade the polylactic acid plastic.

[0010] According to the above scheme, the temperature at which the Arthrosporum fusobacteria degrades polylactic acid plastic is 25-30°C and the pH is 5-7. Preferably, the degradation temperature is 28-30°C.

[0011] In a third aspect, the present invention provides a bacterial agent for degrading polylactic acid plastics, comprising the above-mentioned Arthrospora fusca, wherein Arthrospora fusca LF-2024 is used as an active ingredient of the bacterial agent for degrading polylactic acid plastics.

[0012] According to the above scheme, the bacterial agent is in the form of a liquid bacterial agent obtained by culturing the dark spore arthroncus in a liquid culture medium, a freeze-dried powder form, or a tablet form or an aqueous solution form containing the freeze-dried powder and optional nutrients.

[0013] According to the above scheme, the nutrient that forms the tablet or aqueous solution with the lyophilized powder is an inorganic salt.

[0014] According to the above scheme, the liquid bacterial agent is the culture solution, culture solution concentrate or culture suspension of Arthrospora obscura.

[0015] In a fourth aspect, the present invention provides a method for degrading polylactic acid plastic, comprising the step of contacting the above-mentioned bacterial agent for degrading polylactic acid plastic with polylactic acid plastic.

[0016] According to the above scheme, the bacterial agent is applied to the polylactic acid plastic or a medium containing the polylactic acid plastic, so that the bacterial agent degrades the polylactic acid plastic.

[0017] According to the above scheme, the bacterial agent is applied in the following manner: spraying the liquid bacterial agent on the polylactic acid plastic or a medium containing the polylactic acid plastic so that the bacterial agent contacts the polylactic acid plastic; or

[0018] Sprinkling a freeze-dried bacterial agent on polylactic acid plastic or a medium containing polylactic acid plastic and allowing the bacterial agent to contact the polylactic acid plastic; or

[0019] Sprinkling a tablet-shaped bacterial agent containing the freeze-dried powder and optional nutrients on polylactic acid plastic or a medium containing polylactic acid plastic and allowing the bacterial agent to contact the polylactic acid plastic; or

[0020] The bacterial agent in the form of an aqueous solution containing the freeze-dried powder and optional nutrients is sprayed on the polylactic acid plastic or a medium containing the polylactic acid plastic to allow the bacterial agent to contact the polylactic acid plastic.

[0021] The beneficial effects of the present invention are:

[0022] The present invention screened and obtained a strain of Arthrinium phaeospermum LF-2024, which can grow with polylactic acid plastic as the sole carbon source and effectively degrade the polylactic acid plastic, thus providing a new strain resource for the biodegradation of polylactic acid plastic.

[0023] The Arthrinium phaeospermum LF-2024 can be mass-produced through cultivation, and is used to prepare a polylactic acid degradation bacterial agent, and is applied to the biodegradation of polylactic acid plastic waste in the environment. The production cost is low, the environment is friendly, and the use is convenient, and the application prospect and ecological and environmental protection value are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the growth morphology of strain Arthrinium phaeospermum LF-2024 in Example 1 of the present invention, wherein Figure 1 A is on PDA medium, 1B is on basal salt solid medium containing polylactic acid film;

[0025] Figure 2 The genetic evolution tree of the strain Arthrinium phaeospermum LF-2024 in Example 1 of the present invention;

[0026] Figure 3 is the weight loss rate of the polylactic acid film treated with strain Arthrinium phaeospermum LF-2024 in Example 2 of the present invention;

[0027] Figure 4 This is an infrared spectrum of the polylactic acid film during the treatment of the strain Arthrinium phaeospermum LF-2024 in Example 2 of the present invention;

[0028] Figure 5 This is an environmental scanning electron micrograph of the surface of a polylactic acid film during treatment with the strain Arthrinium phaeospermum LF-2024 in Example 2 of the present invention;

[0029] Figure 6 This is a schematic diagram of the change in water contact angle on the surface of a polylactic acid film during the treatment of the strain Arthrinium phaeospermum LF-2024 in Example 2 of the present invention;

[0030] Figure 7 The tensile properties of the polylactic acid film during the treatment of the strain Arthrinium phaeospermum LF-2024 in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art in the art described herein. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention.

[0033] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0034] Polylactic acid (PLA) plastic is widely used in industry due to its excellent performance. It is difficult to degrade under natural conditions. Microbial degradation is a low-cost, green and pollution-free method. The inventor enriched and screened a fungus LF-2024 from the soil of a landfill, which can grow with polylactic acid plastic as the only carbon source and degrade lactic acid plastic. Morphological and molecular biological identification showed that the fungus is Arthrinium phaeospermum LF-2024, which was deposited in the Guangdong Provincial Microbiological Culture Collection Center GDMCC on February 27, 2025. The address is: 5th Floor, Compound Experimental Building, No. 100 Xianlie Middle Road, Yuexiu District, Guangzhou City, Guangdong Province, and the deposit number is: GDMCC No: 65948.

[0035] In a specific embodiment of the present invention, the above-mentioned Arthrinium phaeospermum LF-2024 is inoculated on a basal salt solid culture medium containing a polylactic acid plastic film. It can grow normally and colonize on the polylactic acid plastic film. After 40 days of culture, the weight loss rate of the polylactic acid plastic film reaches 42.1%, and the weight average and number average molecular weights are significantly reduced. In addition, through environmental scanning electron microscopy, laser infrared imaging spectroscopy and contact angle test analysis, it is found that the surface of the degraded polylactic acid plastic is oxidized, hyphae are attached to the internal fiber surface, and the fibers are expanded. As the treatment time increases, the structure of the PLA plastic film is gradually destroyed, the fungus produces spores, the ester bonds in the polylactic acid molecular chain are broken, the hydrophilic groups on the film surface increase, and the mechanical strength decreases, which proves that the Arthrinium phaeospermum LF-2024 degrades the polylactic acid plastic.

[0036] The Arthrinium phaeospermum LF-2024 can be used for the degradation of polylactic acid plastics, which are polylactic acid plastic powders, particles or films.

[0037] The temperature at which the above-mentioned Arthrosporum obscura degrades polylactic acid plastic is 25-30°C and the pH is 5-7. Preferably, the degradation temperature is 28-30°C.

[0038] The invention also relates to a bacterial agent with the above-mentioned Arthronymus fusus as an active ingredient, which can degrade polylactic acid plastic.

[0039] The above-mentioned bacterial agent for degrading polylactic acid plastic is in the form of a liquid bacterial agent obtained by culturing the dark spore arthroncus in a liquid culture medium, a freeze-dried powder form, or a tablet form or an aqueous solution containing the freeze-dried powder and optional nutrients. The nutrients can be inorganic salts, such as the basic salts in the basic salt solid culture medium in the specific embodiment of the present invention. The liquid bacterial agent is a culture solution, a culture solution concentrate or a culture suspension of dark spore arthroncus.

[0040] Based on the above-mentioned bacterial agent for degrading polylactic acid plastic, the present invention also provides a method for degrading polylactic acid plastic, comprising the step of contacting the above-mentioned bacterial agent for degrading polylactic acid plastic with polylactic acid plastic.

[0041] Specifically, the bacterial agent is applied to polylactic acid plastic or a medium containing polylactic acid plastic, so that the bacterial agent degrades the polylactic acid plastic.

[0042] Specifically, the bacterial agent is applied in the following manner: spraying a liquid bacterial agent on polylactic acid plastic or a medium containing polylactic acid plastic and bringing the bacterial agent into contact with the polylactic acid plastic; or sprinkling a lyophilized powder bacterial agent on polylactic acid plastic or a medium containing polylactic acid plastic and bringing the bacterial agent into contact with the polylactic acid plastic; or sprinkling a tablet bacterial agent containing the lyophilized powder and optional nutrients on polylactic acid plastic or a medium containing polylactic acid plastic and bringing the bacterial agent into contact with the polylactic acid plastic; or spraying a bacterial agent in the form of an aqueous solution containing the lyophilized powder and optional nutrients on polylactic acid plastic or a medium containing polylactic acid plastic and bringing the bacterial agent into contact with the polylactic acid plastic.

[0043] The method of the invention is suitable for degrading polylactic acid in an environment containing polylactic acid plastic waste.

[0044] The culture medium used in the following examples is as follows:

[0045] Basal salt medium (based on 1L): 1g (NH 4 ) 2 SO 4 , 1g K 2 HPO 4 , 0.2gKH 2 PO 4 , 1g NaCl, 0.5mL trace metal salt solution, add water to make up to 1L (add agar for solid culture medium);

[0046] Trace metal salt solution (based on 100 mL): 0.5 mg EDTA, 1 mg CaCO 3 , 2 mg FeSO 4 ·H 2 O, 100mgMgSO 4 7H 2 O, 10 mg MnSO 4 ·H 2 O, 10mL Mixture;

[0047] Mixture solution (based on 100mL): 17.7mgNa 2 B 4 O 7 10H 2 O, 200 mg CuSO 4 ·5H 2 O, 20.1 mg CaCl 2 6H 2 O, 200 mg ZnSO 4 7H 2 O, 250 mg EDTA, 100-150 μL concentrated HO 2 SO 4 ;

[0048] The PLA in the following embodiments may be PLA powder, granules or films according to different usage environments.

[0049] The sterilization method of PLA powder is as follows: PLA powder is placed in a dry sterile culture dish, irradiated under ultraviolet light for 6 hours, and turned every 30 minutes to ensure that the PLA powder is fully sterilized. The ultraviolet sterilized PLA powder is inoculated on PDA and LB solid culture medium, and then cultured at a constant temperature of 30°C for 3 days. If there is no colony growth around the powder, it means that the PLA powder is sterile and can be directly used in the next experiment.

[0050] The sterilization method of PLA plastic film is as follows: place the PLA plastic film in a dry sterile potato dextrose agar (PDA) culture dish, irradiate it under ultraviolet light for 6 hours, and turn it over every 30 minutes to ensure that the PLA plastic film is fully sterilized. Inoculate the ultraviolet sterilized PLA plastic film on the PDA solid culture medium, and then culture it at a constant temperature of 30°C for 3 days. If there is no colony growth around the film, it means that the PLA plastic film is sterile and can be directly used in the next experiment.

[0051] The following are specific embodiments.

[0052] Example 1 Isolation, purification and identification of polylactic acid-degrading bacteria

[0053] (1) Separation and purification

[0054] Enrichment: Sediment samples were collected from soil sediments in landfills. 5 g of sediment samples were weighed and placed in a culture bottle containing 90 mL of physiological saline, and cultured in a constant temperature shaker at 28°C and 180 rpm for 24 hours. Then 2 mL of the suspension was added to 30 mL of basal salt liquid culture medium containing 0.2 g of PLA powder, and mixed in a shaker at 30°C and 180 rpm / min. After culture for 10 days, 2 mL of the bacterial suspension was added to the inorganic salt liquid culture medium containing 0.2 g of PLA, and PLA was used as the sole energy and carbon source. The enrichment was repeated 3 times.

[0055] Isolation and culture: Use physiological saline as diluent, take 100 μL of bacterial solution and dilute it in a continuous gradient, with three parallels for each gradient. For screening PLA-degrading bacteria, choose a basic salt solid medium containing PLA (0.2g PLA powder dissolved in 30mL medium). All solid culture media are inverted and cultured in a constant temperature incubator at 28°C for 72h.

[0056] A fungus strain was screened and was able to grow on inorganic salt solid medium containing PLA with PLA as the sole carbon source, and was named LF-2024.

[0057] (2) Growth characteristics and species identification of fungus LF-2024

[0058] a. Growth of fungus LF-2024 in basal salt medium with PLA as the sole carbon source

[0059] The fungus LF-2024 isolated and screened was inoculated into PDA solid culture medium and cultured until the hyphae covered the entire plate. The hyphae blocks with a diameter of about 0.5 cm were punched with a hole puncher and transferred to a basal salt solid culture medium covered with 0.1 g PLA plastic film for 20 days to observe the growth of the hyphae.

[0060] The results are as follows Figure 1 As shown, Figure 1 A shows the mycelial growth after 5 days of culture on PDA medium. The mycelium is well developed and white and flocculent. It is white at the beginning and then gradually turns red. Figure 1 B shows the growth of mycelium on a basal salt solid culture medium covered with a PLA plastic film. The mycelium of LF-2024 grows along the PLA plastic film in a basal salt solid culture medium containing a PLA plastic film. The mycelium is well developed, and the middle mycelium produces red and dark red pigments.

[0061] b. 16S rDNA identification and phylogenetic tree construction of fungus LF-2024

[0062] The fungus was cultured in PDA medium at 28°C for 2-3 days. Mycelium was removed from the culture medium using a sterile inoculation loop, transferred to a liquid culture medium, and then cultured at 28°C for 3 days. The mycelium was collected, and after lysis, centrifugation and dilution, a template for PCR amplification was obtained. The 16S rDNA fragment was obtained by PCR amplification, and the amplified product was recovered and sent to Qingke Biotechnology Co., Ltd. (Wuhan) for sequencing, and the blastn algorithm was used to query the National Center for Biotechnology Information (NCBI) database. Homologous strains were selected from the NCBI nucleotide database for identification, and then the sequences were phylogenetically analyzed using the ClustalW tool in MEGA-X. Finally, a phylogenetic tree was constructed using the maximum likelihood tree construction method. After Blast alignment of the sequencing results in the NCBI database, the results showed that the DNA gene sequence of the strain was more than 99% similar to that of Arthrinium phaeospermum. 20 bacterial DNA gene sequences with similar homology were selected to construct a phylogenetic tree, such as Figure 2 These strains were located on the same branch as Arthrinium phaeospermum, indicating a close genetic relationship.

[0063] According to the above molecular biological identification results and evolutionary tree, the fungus LF-2024 was determined to be Arthrinium phaeospermum and was named Arthrinium phaeospermum LF-2024.

[0064] Example 2 Degradation of PLA by Arthrinium phaeospermum LF-2024

[0065] In this embodiment, PLA plastic film is taken as an example to test the degradation of PLA plastic by Arthrinium phaeospermum LF-2024.

[0066] Through experimental exploration, the temperature for the degradation of PLA plastic by Arthrinium phaeospermum LF-2024 is 25-30°C, preferably 28-30°C, and the pH value of degradation is 5-7. The degradation temperature of the following experiment is 28°C and the pH value is 7.

[0067] Experimental group: Arthrinium phaeospermum LF-2024 was inoculated into PDA solid medium and cultured until the hyphae covered the entire plate. The hyphae blocks of about 0.5 cm were punched with a hole puncher and transferred to the basal salt solid medium covered with 0.1g PLA plastic film for a certain period of time. The weight loss rate of the film, the molecular weight of the degradation product, and the characterization and analysis of the treated PLC plastic film were measured. The hyphae of Arthrinium phaeospermum LF-2024 were not inoculated in the control group.

[0068] (1) Film weight loss analysis

[0069] The films were taken out and weighed on the 10th, 20th and 40th days respectively. In order to accurately determine the weight loss rate of the PLA plastic film, the PLA needs to be cleaned and recovered from the culture medium, and the steps are as follows: soak in PBS for 2 minutes; soak in 2% SDS for 2 hours; pour out the liquid, wash 2-3 times with warm distilled water; soak in 2% pentanediol for 2 hours; pour out the liquid, sonicate 2 times with 50% ethanol (30 minutes each time, and the ethanol needs to be replaced each time); 75% ethanol overnight; pour out the liquid, wash 3 times with 100% anhydrous ethanol (30 minutes each time, and the ethanol needs to be replaced each time), pour out the liquid, and dry; use a 1 / 10,000 analytical balance to measure the weight of the residue.

[0070] The weight loss rate of PLA is calculated as follows: Weight loss rate % = (initial weight - weight after culture) / initial weight × 100%

[0071] The results are as follows Figure 3 As shown in the figure, with the increase of treatment time, the weight loss rate of PLA plastic film in the control group did not decrease significantly, and the weight loss rate was only 3.6% after 40 days. In the experimental group, the weight loss rate of PLA plastic film treated with the degradation bacteria Arthrinium phaeospermum LF-2024 increased significantly with the increase of treatment time, and the weight loss rate of PLA plastic film was 42.1% after 40 days, indicating that Arthrinium phaeospermum LF-2024 degraded PLA plastic film.

[0072] (2) Gel permeation chromatography (GPC) analysis

[0073] On the 40th day, the PLA plastic films of the experimental group and the control group were subjected to gel permeation chromatography analysis to determine the number average molecular weight (Mn), weight average molecular weight (Mw) and dispersion coefficient of the films. The results are shown in Table 1 below.

[0074] Table 1 Number average molecular weight, weight average molecular weight and dispersion coefficient of PLA plastic films in the experimental group and the control group after 40 days

[0075]

[0076] After fungal treatment, the number average molecular weight and weight average molecular weight of the PLA plastic film decreased by 81.6% and 78.0% respectively. The molecular weight decreased significantly and the molecular weight dispersion coefficient increased, indicating that the PLA plastic film underwent a polymerization reduction reaction, the molecular weight distribution range became wider, and the molecular weight difference became greater.

[0077] (3) Characterization and analysis of PLA plastic films after biotreatment with Arthrinium phaeospermum LF-2024

[0078] In order to detect the changes of samples during the degradation process, Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) test, environmental scanning electron microscopy (ESEM) analysis, water contact angle (CA) analysis and tensile properties analysis were performed on the treated PLA plastic film samples on the 0th, 10th, 20th and 40th days of treatment, respectively.

[0079] a. FTIR-ATR test results are as follows Figure 4 As shown, these samples have a high -1 The polylactic acid film contrast is at 1749cm -1 There is an obvious carbonyl (-C=O) characteristic absorption peak at 1749cm -1The carbonyl stretching vibration peak at 1500-1600 cm -1 The plane bending vibration of the hydroxyl group shows obvious fluctuations (alcohol hydroxyl group, -OH), which means that as the degradation proceeds, more lower alcohol products are produced. In addition, the 3300 cm -1 The obvious absorption bands appeared at the bottom, which means that the carboxylic acid generated by the degradation of polylactic acid plastic forms carboxylic acid dimers due to intermolecular hydrogen bonding. These changes indicate that the polylactic acid bonds, the main component of the PLA plastic film, were hydrolyzed and broken after being treated by fungi, and the PLA plastic film was degraded.

[0080] b. Environmental scanning electron microscopy results Figure 5 As shown in the figure, it can be seen that the structure of the PLA plastic film that has not been treated with Arthrinium phaeospermum LF-2024 is neatly arranged and the fiber surface is smooth. After being treated with Arthrinium phaeospermum LF-2024, hyphae are attached to the internal fiber surface of the PLA plastic film, accompanied by the expansion of the fiber. As the treatment time increases, cracks appear in the PLA plastic film, the structure is gradually destroyed, and the fungus produces spores. This proves that the fungus destroys the structure of the PLA plastic film and degrades the PLA plastic film. Arthrinium phaeospermum LF-2024 grows with polylactic acid as the only carbon source, colonizes on the surface of the plastic film, and gradually degrades the plastic.

[0081] c. Water contact angle is used to characterize the hydrophobicity change of PLA plastic film before and after treatment. The results are shown in Figure 6 As shown in the figure, the PLA plastic film that has not been treated with Arthrinium phaeospermum LF-2024 has a large hydrophobicity (θ=147.6°). During the treatment process, the water contact angle of the PLA plastic film decreases with the increase of treatment time, and drops to 62.1° on the 40th day. This shows that the hydrophilicity of the PLA plastic film treated with Arthrinium phaeospermum LF-2024 increases, indicating that the fungus destroys the structure of the PLA plastic film and exposes the hydrophilic groups, resulting in an increase in the hydrophilicity of the PLA plastic film. As shown in the FTIR-ATR test, a large number of ester bonds (-COO-) contained in the PLA plastic film are decomposed into hydroxyl (-OH) and carboxyl (-COOH) groups by the enzymes produced by the fungi, both of which can form hydrogen bonds and combine with water, resulting in a macroscopic transformation of the PLA plastic film from hydrophobic to hydrophilic.

[0082] d. Tensile test results are as follows Figure 7As shown in the figure, the tensile stress of the PLA plastic film that has not been treated with Arthrinium phaeospermum LF-2024 is 1.8 MPa, and the tensile stress of the film after 40 days of treatment is only 0.05 MPa. The mechanical properties of the film decrease with the extension of the treatment time, indicating that the growth of fungi destroys the mechanical properties of the PLA plastic film, indirectly proving its degradation effect on the PLA plastic film.

[0083] Example 3

[0084] The above-mentioned Arthrinium phaeospermum LF-2024 is prepared into a bacterial agent for degrading polylactic acid plastic.

[0085] Specifically, Arthrinium phaeospermum LF-2024 is directly inoculated into a liquid culture medium for cultivation to obtain the culture solution containing Arthrinium phaeospermum LF-2024, or the culture solution is concentrated to obtain a culture solution concentrate, or the culture suspension is obtained after centrifugation and resuspension, all of which belong to liquid bacterial agents.

[0086] Arthrinium phaeospermum LF-2024 is directly inoculated into a liquid culture medium for expansion culture, and the obtained Arthrinium phaeospermum LF-2024 is freeze-dried to obtain a freeze-dried powder of Arthrinium phaeospermum LF-2024, or the freeze-dried powder and optional nutrients are made into tablets; or the freeze-dried powder and optional nutrients are prepared into an aqueous solution, all of which belong to different forms of bacterial agents. The nutrient can be an inorganic salt.

[0087] The above-mentioned bacterial agent can be used to treat polylactic acid plastic or waste containing polylactic acid plastic. Specifically, it is suitable for degrading lactic acid in a medium containing polylactic acid plastic or a medium of a material composed entirely or partially of polylactic acid, such as a mixture of household or industrial waste containing polylactic acid plastic, an organic waste mixture, etc.

[0088] Specifically, a liquid bacterial agent is sprayed on polylactic acid plastic or a medium containing polylactic acid plastic and the bacterial agent is in contact with the polylactic acid plastic; or a lyophilized powder bacterial agent is sprinkled on polylactic acid plastic or a medium containing polylactic acid plastic and the bacterial agent is in contact with the polylactic acid plastic; or a tablet bacterial agent containing the lyophilized powder and optional nutrients is sprinkled on polylactic acid plastic or a medium containing polylactic acid plastic and the bacterial agent is in contact with the polylactic acid plastic; or a bacterial agent in the form of an aqueous solution containing the lyophilized powder and optional nutrients is sprayed on polylactic acid plastic or a medium containing polylactic acid plastic and the bacterial agent is in contact with the polylactic acid plastic, thereby degrading the polylactic acid plastic in the medium.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A dark spore arthroncus, characterized in that It is Arthrinium phaeospermum LF-2024, which is deposited in Guangdong Microbiological Culture Collection Center with the deposit number GDMCC No: 65948.

2. Use of the dark spore Arthronymus as claimed in claim 1 in degrading polylactic acid plastics.

3. The use according to claim 2, characterized in that: The polylactic acid plastic is polylactic acid plastic powder, granules or film.

4. The use according to claim 2, characterized in that: The dark spore arthroncus grows with polylactic acid plastic as the only carbon source and degrades the polylactic acid plastic.

5. A bacterial agent for degrading polylactic acid plastic, characterized in that: It comprises the dark spore arthroncus of claim 1.

6. The bacterial agent according to claim 5, characterized in that The invention is in the form of a liquid bacterial agent obtained by culturing the Arthrospora obscura in a liquid culture medium, a freeze-dried powder, or a tablet or aqueous solution containing the freeze-dried powder and optional nutrients.

7. The bacterial agent according to claim 6, characterized in that The liquid bacterial agent is a culture solution, a culture solution concentrate or a culture suspension of Arthrospora obscura.

8. A method for degrading polylactic acid plastic, characterized in that: The method comprises the step of contacting the bacterial agent for degrading polylactic acid plastic as described in any one of claims 5 to 7 with polylactic acid plastic.

9. The method for degrading polylactic acid plastic according to claim 8, characterized in that: The bacterial agent is applied to polylactic acid plastic or a medium containing polylactic acid plastic, so that the bacterial agent degrades the polylactic acid plastic.

10. The method for degrading polylactic acid plastic according to claim 9, characterized in that: The bacterial agent is applied in the following manner: spraying the liquid bacterial agent on the polylactic acid plastic or a medium containing the polylactic acid plastic so that the bacterial agent contacts the polylactic acid plastic; or Sprinkling a freeze-dried bacterial agent on polylactic acid plastic or a medium containing polylactic acid plastic and allowing the bacterial agent to contact the polylactic acid plastic; or Sprinkling a tablet-shaped bacterial agent containing the freeze-dried powder and optional nutrients on polylactic acid plastic or a medium containing polylactic acid plastic and allowing the bacterial agent to contact the polylactic acid plastic; or The bacterial agent in the form of an aqueous solution containing the freeze-dried powder and optional nutrients is sprayed on the polylactic acid plastic or a medium containing the polylactic acid plastic to allow the bacterial agent to contact the polylactic acid plastic.

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