Bacillus licheniformis and application thereof in degradation of malondialdehyde in grease

Abstract

The invention relates to the technical field of feed microorganisms, and particularly discloses bacillus licheniformis and application of the bacillus licheniformis in degradation of malondialdehyde in grease. The bacillus licheniformis PL-O-1-5 provided by the invention is classified and named as bacillus licheniformis, the bacillus licheniformis is preserved in the China General Microbiological Culture Collection Center (CGMCC) on November 26, 2025, and the preservation number is CGMCC No.36782. The bacillus licheniformis PL-O-1-5 can be used for preparing the bacillus licheniformis. The bacillus licheniformis PL-O-1-5 strain provided by the invention has excellent properties of acid resistance, salt resistance, sugar resistance and oil resistance, has very strong tolerance, and can be applied to various feed raw materials and feeds; through fermentation treatment, a certain effect on preventing rancidity of feed and raw material grease is achieved, meanwhile, the malondialdehyde value in rancidified feed can be reduced, and certain safety is achieved.

Description

Technical Field

[0001] This application relates to the technical field of feed microorganisms, specifically to a Bacillus licheniformis and its application in degrading malondialdehyde in oils. Background Technology

[0002] With the development of the feed industry, oils have been widely used. As a high-energy feed, oils not only provide livestock and poultry with sufficient fatty acids but also significantly improve feed palatability and increase feed conversion rate. However, they are prone to oxidative rancidity during storage, processing, and use, which has become a common problem faced by feed manufacturers both domestically and internationally. Rancidity not only reduces the nutritional value of animals but also affects their feed intake, health, and production performance, causing serious economic losses to farmers and producers. Feed rancidity has become an urgent problem to be solved in actual production.

[0003] In this study, malondialdehyde (MDA) content was used as an important indicator for evaluating the degree of feed oxidative rancidity. As a total byproduct of lipid oxidation, MDA causes cross-linking and polymerization of biomolecules such as proteins and nucleic acids, exhibiting cytotoxicity. As a significant toxic and harmful substance in feed rancidity, MDA ingestion by livestock and poultry can easily induce oxidative stress, leading to damage to tissue cell membrane structure, reduced liver antioxidant capacity, and decreased animal production performance and meat quality, causing significant economic losses to the livestock industry. Furthermore, excessive MDA accumulates in animal-derived foods and eventually enters the human body, harming health.

[0004] Therefore, reducing the malondialdehyde content in feed oils through bio-fermentation is crucial for the production performance and health of livestock and poultry. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a Bacillus licheniformis and its application in the degradation of malondialdehyde in oils.

[0006] In the first aspect, this application provides a Bacillus licheniformis PL-O-1-5, classified and named Bacillus licheniformis, which was deposited on November 26, 2025, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36782, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0007] In a specific implementation scheme, the *Bacillus licheniformis* PL-O-1-5 colonies have a rough surface and irregularly shaped edges. After staining, the strain appears as short rods with spores, are elliptical in shape, and have swollen sporangia. This *Bacillus licheniformis* PL-O-1-5 exhibits good resistance to sugar, acid, salt, and oil, and can survive and exert its effects in various feeds.

[0008] This application aims to provide a Bacillus licheniformis PL-O-1-5 strain with accession number CGMCC No.36782. This strain is acid-resistant, salt-resistant, sugar-resistant, and oil-resistant, exhibiting strong tolerance. Furthermore, through fermentation treatment, it can efficiently reduce the malondialdehyde (MDA) content in feed oils. This not only plays a role in preventing the rancidity of feed and raw material oils but also reduces the MDA value in already rancid feeds.

[0009] Preferably, the Bacillus licheniformis PL-O-1-5 is acid-resistant, with a survival rate ≥70.0% under pH 4.0 conditions; the Bacillus licheniformis PL-O-1-5 is salt-resistant, with a survival rate ≥95% under 5% high salt conditions; and the Bacillus licheniformis PL-O-1-5 is sugar-resistant, with a survival rate ≥85% under 10% high sugar conditions.

[0010] In a specific implementation scheme, the Bacillus licheniformis PL-O-1-5 exhibits acid resistance, with a survival rate of 71.64% at pH 4.0; it also exhibits salt resistance, with a survival rate of 96.47% at 5% high salt conditions; and it further exhibits sugar resistance, with a survival rate of ≥86% at 10% high sugar conditions.

[0011] Furthermore, the Bacillus licheniformis PL-O-1-5 isolation and screening method involves acclimatization and oil degradation acclimatization experiments, which demonstrates a certain degree of oil tolerance and allows it to grow well in culture media containing high concentrations of oil.

[0012] Secondly, this application provides a bacterial agent containing the aforementioned Bacillus licheniformis PL-O-1-5.

[0013] Thirdly, this application provides a fermentation broth obtained by fermenting the aforementioned Bacillus licheniformis PL-O-1-5.

[0014] Fourthly, this application provides a method for preparing the fermentation broth, comprising the following steps: (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured statically at 25-40℃ for 24-48h. Single colonies were screened and inoculated into modified LB medium and cultured with shaking at 25-40℃ for 18-48h to obtain activated seed culture. (2) Preparation of fermentation broth: Inoculate the activated seed liquid into the modified LB medium at a volume percentage of 0.5-10%, shake and culture for 24-48h, then centrifuge at 5000-12000rpm for 10-20min, and take the supernatant to obtain the fermentation broth.

[0015] Preferably, the method for preparing the fermentation broth includes the following steps: (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured statically at 35-39℃ for 24-48h. Single colonies were screened and inoculated into modified LB medium and cultured with shaking at 35-39℃ for 18-48h to obtain activated seed culture. (2) Preparation of fermentation broth: Inoculate the activated seed liquid into the modified LB medium at a volume percentage of 1-5%, shake and culture for 36-48h, centrifuge at 8000-12000rpm for 10-15min, and take the supernatant to obtain the fermentation broth.

[0016] The method for preparing Bacillus licheniformis PL-O-1-5 fermentation broth provided in this application has the advantages of simple process and easy industrialization.

[0017] By adopting the above technical solution, the supernatant obtained by centrifuging the fermentation broth from Bacillus licheniformis PL-O-1-5 can effectively delay the rancidity of feed raw materials and feed, inhibit the production of malondialdehyde (MDA), and efficiently degrade the MDA value in rancid feed oils. Naturally, the supernatant obtained after centrifuging the fermentation broth also includes the original fermentation broth obtained after inoculating the activated seed culture into modified LB medium for fermentation. Therefore, the fermentation broth obtained by fermenting Bacillus licheniformis PL-O-1-5 in this application can refer to the original fermentation broth obtained after inoculating the seed culture into modified LB medium for fermentation, or it can be the supernatant obtained after centrifuging the original fermentation broth.

[0018] Preferably, the modified LB medium comprises the following components at the following concentrations: tryptone 7-8 g / L, yeast extract 7-8 g / L, magnesium nitrate 2-3 g / L, and pH 7 ± 0.2; the modified LB solid medium comprises the following components at the following concentrations: tryptone 7-8 g / L, yeast extract 7-8 g / L, magnesium nitrate 2-3 g / L, agar 14-16 g / L, and pH 7.0 ± 0.2.

[0019] Preferably, the modified LB medium comprises the following components at the following concentrations: tryptone 7.2-7.8 g / L, yeast extract 7.2-7.8 g / L, magnesium nitrate 2.2-2.8 g / L, and pH 7±0.2; the modified LB solid medium comprises the following components at the following concentrations: tryptone 7.2-7.8 g / L, yeast extract 7.2-7.8 g / L, magnesium nitrate 2.2-2.8 g / L, agar 14.5-15.5 g / L, and pH 7.0±0.2.

[0020] Fifthly, this application provides a biological agent comprising the Bacillus licheniformis PL-O-1-5 and / or the fermentation broth.

[0021] Sixthly, this application provides the application of the Bacillus licheniformis PL-O-1-5, or the bacterial agent, or the fermentation broth, or the biological agent in the degradation of malondialdehyde in oils.

[0022] Seventhly, this application provides a method for degrading malondialdehyde in oils and fats, comprising the following steps: (1) The Bacillus licheniformis PL-O-1-5 was inoculated into a culture medium and fermented to obtain a fermentation broth; (2) Mix the fermentation broth with the oil to be treated thoroughly and incubate at a constant temperature of 30-40℃ to degrade malondialdehyde in the oil.

[0023] In summary, the technical solution of this application has the following effects: The Bacillus licheniformis PL-O-1-5 strain provided in this application has excellent resistance to acid, salt, sugar, and oil, and has strong tolerance, making it suitable for use in a variety of feed ingredients and feeds; and through fermentation treatment, it can effectively reduce the malondialdehyde content in feed oils.

[0024] The Bacillus licheniformis PL-O-1-5 fermentation broth provided in this application has a certain effect on preventing the rancidity of feed and raw material oils, and can also reduce the malondialdehyde value in rancid feed.

[0025] The Bacillus licheniformis PL-O-1-5 provided in this application is safe in the category of feed additives and is beneficial to feed preparation and application; compared with chemical removal methods, the biodegradation of malondialdehyde by Bacillus licheniformis PL-O-1-5 has a certain degree of safety. Attached Figure Description

[0026] Figure 1 This is a colony diagram of Bacillus licheniformis PL-O-1-5 in this application.

[0027] Figure 2 This is an image of Bacillus licheniformis PL-O-1-5 after Gram staining in this application. Detailed Implementation

[0028] The present application will be further described in detail below with reference to embodiments, comparative examples and performance test results. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0029] This application provides a strain of Bacillus licheniformis PL-O-1-5, which was isolated and screened from food waste. The strain was identified as Bacillus licheniformis by 16S rDNA testing and named Bacillus licheniformis PL-O-1-5. It was deposited on November 26, 2025, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36782, located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0030] This application also provides a fermentation broth obtained from Bacillus licheniformis PL-O-1-5 with accession number CGMCC No. 36782, specifically obtained through the following steps of cultivation and fermentation: (1) Preparation of Bacillus licheniformis PL-O-1-5 seed culture: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and statically cultured at 25-40℃ (e.g., 25℃, 28℃, 35℃, 40℃) for 24-48h (e.g., 24h, 32h, 40h, 48h). Larger single colonies were screened and inoculated into modified LB medium and shaken at 25-40℃ (e.g., 25℃, 28℃, 35℃, 40℃) for 18-32h (e.g., 18h, 22h, 26h, 32h). (2) Preparation of Bacillus licheniformis PL-O-1-5 fermentation broth: The activated seed liquid was inoculated into modified LB medium at a volume percentage of 0.5-10% (e.g., 0.5%, 2%, 5%, 10%), and cultured with shaking for 24-48h (e.g., 24h, 32h, 40h, 48h). After centrifugation at 5000-12000rpm (e.g., 5000rpm, 8000rpm, 10000rpm, 12000rpm) for 10-20min (e.g., 10min, 15min, 20min), the supernatant was collected to obtain the fermentation broth.

[0031] The culture media and raw material sources involved in the following examples are as follows: LB solid medium: tryptone 10 g / L, yeast extract 5 g / L, sodium chloride 10 g / L, agar 15 g / L, pH 7.0 ± 0.2.

[0032] LB medium: 10 g / L tryptone, 5 g / L yeast extract, 10 g / L sodium chloride, pH 7.0 ± 0.2.

[0033] In the following examples, strain activation refers to the process of streaking the strain from a preservation tube onto a solid culture medium plate and allowing a single colony to grow.

[0034] Example

[0035] Example 1

[0036] This embodiment provides a Bacillus licheniformis PL-O-1-5 strain and its isolation and screening method.

[0037] The isolation and screening method of Bacillus licheniformis strain PL-O-1-5 in this embodiment is as follows.

[0038] (1) Enrichment: Weigh 10g of food waste into 100mL of sterile water with glass beads and shake to prepare a suspension. Add 2mL of each suspension to a 50mL Erlenmeyer flask containing LB medium. Place the Erlenmeyer flasks in a shaker at 28℃ and 37℃ for 1-5 days (judging by the turbidity of the culture medium). Aseptically transfer the flasks to fresh liquid enrichment medium (enrichment medium contains 10.0g / L tryptone, 5.0g / L yeast extract, and 10.0g / L sodium chloride, with pH gradients of 6.0, 7.0, and 7.8, and perform parallel culture). Enrich three times consecutively to obtain the enriched culture medium.

[0039] (2) Acclimation Culture: The above-mentioned enriched culture solution was used for the acclimation experiment of the strain's lipid degradation. The soybean oil concentration was increased in a gradient (10 g / L, 15 g / L, 20 g / L), and the culture was shaken and cultured at a constant temperature for 5 days. Before acclimation, 10 mL of the enriched culture solution was inoculated into a fresh acclimation culture medium with a soybean oil concentration of 10 g / L and cultured for one cycle; then 10 mL of the culture solution was taken from the enriched culture solution and added to a fresh acclimation culture medium with a soybean oil concentration of 15 g / L for one cycle. After three cycles of culture, the lipid concentration of the acclimation culture medium in each cycle was higher than that of the acclimation solution after the end of the previous week, which was used for strain purification.

[0040] (3) Isolation: The clear zone method was used for bacterial isolation and purification. The bacterial strain was diluted and spread onto malondialdehyde plates (10 μg / mL). After inoculation, the plates were placed in constant temperature incubators at 28℃ and 37℃ for static incubation. After the colonies grew, they were developed with thiobarbituric acid at 90℃. Colonies with larger hydrolysis zones were selected as the target strain. The isolation and culture were repeated multiple times until the colony morphology was relatively consistent, which was considered as obtaining a pure strain. The strain was then cultured on slant plates and stored.

[0041] (4) Biological identification of the target strain: The isolated strain was inoculated into LB medium and cultured at 37°C for 24 hours. Morphological identification and 16S rDNA molecular biological identification were performed. The strain identification was performed by BGI Genomics Co., Ltd.

[0042] 138 colonies with clear zones were screened from waste cooking oil. Strains with larger clear zones were selected and amplified using 16S rDNA sequencing. The sequences were compared with those obtained using GenBank BLAST and showed 99% similarity to *Bacillus licheniformis*. This strain was named *Bacillus licheniformis* PL-O-1-5.

[0043] like Figure 1 This is a colony diagram of Bacillus licheniformis PL-O-1-5 in this application. As shown in the figure, the colony surface of Bacillus licheniformis is rough, and the edges are irregularly shaped.

[0044] like Figure 2 This is an observation image of Bacillus licheniformis PL-O-1-5 after Gram staining in this application. As shown in the image, after staining, the Bacillus licheniformis strain appears as short rods with spores, which are oval in shape and have swollen sporangia.

[0045] Example 2

[0046] In this embodiment, the tolerance of Bacillus licheniformis strain PL-O-1-5 was analyzed.

[0047] (1) Screening of acid-resistant strains Beef extract peptone medium with pH values ​​of 4.0, 4.5, and 5.0 was prepared, and Bacillus licheniformis strain PL-O-1-5 was diluted to a concentration of 1×10⁻⁶. 7 The concentrations were determined, and the plates were spread on plates under different pH conditions. The plates were then incubated at 37°C under the same conditions. After 2 days, the growth of the strains on the plates under different pH conditions was compared.

[0048] (2) Screening of salt-tolerant strains Beef extract peptone culture medium with NaCl concentrations of 2.5% and 5% was prepared, and Bacillus licheniformis strain PL-O-1-5 was diluted to a concentration of 1×10⁻⁶. 7 The concentrations of NaCl were determined, and the plates were spread on plates with different NaCl concentrations. The plates were then placed in a 37°C incubator under the same conditions. After 2 days, the growth of the strains on the plates with different NaCl concentrations was compared.

[0049] (3) Screening of sugar-tolerant strains Beef extract peptone culture media with sugar concentrations of 2.5%, 5%, and 10% were prepared, and Bacillus licheniformis strain PL-O-1-5 was diluted to 1×10⁻⁶ ppm. 7 The concentrations were determined by spreading the bacteria on plates with different sugar concentrations and incubating them in a 37°C incubator. All other conditions were kept the same, and the growth of the bacteria on the plates with different sugar concentrations was compared after 2 days.

[0050] The results are shown in Table 1.

[0051] Table 1. Survival rate of Bacillus licheniformis PL-O-1-5 under different conditions

[0052] Example 3

[0053] This embodiment provides a method for degrading malondialdehyde in rancid palm oil using Bacillus licheniformis.

[0054] The specific method for degrading malondialdehyde in rancid palm oil in this embodiment is as follows.

[0055] In this embodiment, the method for degrading malondialdehyde in rancid palm oil uses different modified LB solid medium / modified LB medium to culture Bacillus licheniformis PL-O-1-5 strain, the specific composition of which is shown in Table 2.

[0056] Table 2. Composition of modified LB solid medium / modified LB medium in Example 3

[0057] (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured at 37℃ for 24h. Larger single colonies were screened and inoculated into modified LB medium and cultured at 37℃ with shaking for 48h to obtain Bacillus licheniformis PL-O-1-5 seed culture.

[0058] (2) Bacillus licheniformis PL-O-1-5 seed culture was mixed with palm oil at a volume percentage of 10%, and a blank control group was set up. The mixture was incubated at a constant temperature of 37℃ for 2 hours. The malondialdehyde content of the two groups was measured by TBA colorimetric method. The results are shown in Table 3.

[0059] Table 3. Results of Bacillus licheniformis degradation of malondialdehyde in rancid palm oil

[0060] As shown in Table 3, the malondialdehyde (MDA) content in palm oil after 2 hours of mixing was significantly lower than that before mixing. Therefore, it can be inferred that directly mixing the Bacillus licheniformis PL-O-1-5 fermentation broth with oil can effectively degrade MDA in rancid palm oil.

[0061] Comparing the experimental results of Examples 3-1 and 3-6, it can be found that the seed culture of Bacillus licheniformis PL-O-1-5 prepared in Example 3-6 using traditional LB solid medium / LB medium showed only a moderate effect on the degradation of malondialdehyde in oils. However, the seed culture of Bacillus licheniformis PL-O-1-5 prepared in Example 3-5 using LB solid medium / LB medium containing 10 g / L tryptone, 5 g / L yeast extract, and 2.5 g / L magnesium nitrate, or the seed culture of Bacillus licheniformis PL-O-1-5 prepared in Example 3-4 using LB solid medium / LB medium containing 7.5 g / L tryptone, 7.5 g / L yeast extract, and 2.5 g / L magnesium chloride, effectively improved the degradation effect of malondialdehyde in oils. In contrast, this application uses LB solid medium / LB medium containing 7-8 g / L tryptone, 7-8 g / L yeast extract and 2-3 g / L magnesium nitrate to culture Bacillus licheniformis PL-O-1-5, and the resulting seed culture effectively improves the degradation effect of malondialdehyde in oils.

[0062] Example 4

[0063] This embodiment provides a method for preventing soybean oil rancidity using Bacillus licheniformis.

[0064] The specific method for preventing soybean oil rancidity in this embodiment is as follows.

[0065] (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured at 37℃ for 24h. Larger single colonies were screened and inoculated into modified LB medium and cultured at 37℃ with shaking for 48h to obtain activated Bacillus licheniformis PL-O-1-5 seed culture.

[0066] (2) Bacillus licheniformis PL-O-1-5 seed culture was mixed with soybean oil at a volume percentage of 10%, and a blank control group was set up. The mixture was cultured at a constant temperature of 37℃ and left open for 7 days. The malondialdehyde content in the two groups was measured by TBA colorimetric method. The results are shown in Table 4.

[0067] Table 4. Experimental results of Bacillus licheniformis in preventing soybean oil rancidity.

[0068] The results in the table show that after 7 days, the malondialdehyde (MDA) content in the soybean oil from the control group was significantly higher than that in the soybean oil from the fermentation broth. Therefore, it can be inferred that the Bacillus licheniformis PL-O-1-5 fermentation broth can prolong the rancidity time of soybean oil and increase its shelf life.

[0069] Example 5

[0070] This embodiment provides a method for degrading malondialdehyde in rancid feed using Bacillus licheniformis.

[0071] The specific method for degrading malondialdehyde in rancid feed in this embodiment is as follows.

[0072] (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured at 37℃ for 24h. Larger single colonies were screened and inoculated into modified LB medium and cultured at 37℃ with shaking for 48h to obtain activated Bacillus licheniformis PL-O-1-5 seed culture.

[0073] (2) Degradation test: Bacillus licheniformis PL-O-1-5 seed liquid was inoculated into rancid feed at a volume percentage of 10%, and then 5% water was added. The feed was then statically cultured at 37℃ for 24 h. The malondialdehyde content before and after fermentation of the rancid feed was determined by the TBA colorimetric method. The results are shown in Table 5.

[0074] Table 5. Results of Bacillus licheniformis degradation of malondialdehyde in rancid feed

[0075] The results in the table show that the malondialdehyde (MDA) content in the treated rancid feed was significantly lower than that in the untreated rancid feed. Therefore, it can be inferred that the Bacillus licheniformis PL-O-1-5 fermentation broth can effectively degrade MDA in rancid feed.

[0076] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A Bacillus licheniformis PL-O-1-5, characterized in that, The strain was classified and named Bacillus licheniformis, and was deposited on November 26, 2025, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36782. The deposit address is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

2. A bacterial agent comprising Bacillus licheniformis PL-O-1-5 as described in claim 1.

3. A fermentation broth, characterized in that, It is obtained by fermentation of Bacillus licheniformis PL-O-1-5 as described in claim 1.

4. A method for preparing the fermentation broth as described in claim 3, characterized in that, Includes the following steps: (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured statically at 25-40℃ for 24-48h. Single colonies were screened and inoculated into modified LB medium and cultured with shaking at 25-40℃ for 18-48h to obtain activated seed culture. (2) Preparation of fermentation broth: Inoculate the activated seed liquid into the modified LB medium at a volume percentage of 0.5-10%, shake and culture for 24-48h, then centrifuge at 5000-12000rpm for 10-20min, and take the supernatant to obtain the fermentation broth.

5. The method for preparing fermentation broth according to claim 4, characterized in that, Includes the following steps: (1) Seed culture preparation: Bacillus licheniformis PL-O-1-5 strain was inoculated into modified LB solid medium and cultured statically at 35-39℃ for 24-48h. Single colonies were screened and inoculated into modified LB medium and cultured with shaking at 35-39℃ for 18-48h to obtain activated seed culture. (2) Preparation of fermentation broth: Inoculate the activated seed liquid into the modified LB medium at a volume percentage of 1-5%, shake and culture for 36-48h, centrifuge at 8000-12000rpm for 10-15min, and take the supernatant to obtain the fermentation broth.

6. The method for preparing fermentation broth according to claim 4, characterized in that, The modified LB medium comprises the following components at the following concentrations: tryptone 7-8 g / L, yeast extract 7-8 g / L, magnesium nitrate 2-3 g / L, pH 7±0.2; the modified LB solid medium comprises the following components at the following concentrations: tryptone 7-8 g / L, yeast extract 7-8 g / L, magnesium nitrate 2-3 g / L, agar 14-16 g / L, pH 7.0±0.

2.

7. The method for preparing fermentation broth according to claim 6, characterized in that, The modified LB medium comprises the following components at the following concentrations: tryptone 7.2-7.8 g / L, yeast extract 7.2-7.8 g / L, magnesium nitrate 2.2-2.8 g / L, with a pH of 7±0.2; the modified LB solid medium comprises the following components at the following concentrations: tryptone 7.2-7.8 g / L, yeast extract 7.2-7.8 g / L, magnesium nitrate 2.2-2.8 g / L, agar 14.5-15.5 g / L, with a pH of 7.0±0.

2.

8. A biological agent, characterized in that, It includes Bacillus licheniformis PL-O-1-5 as described in claim 1, and / or the fermentation broth as described in claim 3.

9. The application of Bacillus licheniformis PL-O-1-5 as described in claim 1, or the bacterial agent as described in claim 2, or the fermentation broth as described in claim 3, or the biological agent as described in claim 8 in the degradation of malondialdehyde in oils.

10. A method for degrading malondialdehyde in oils and fats, characterized in that, Includes the following steps: (1) The Bacillus licheniformis PL-O-1-5 of claim 1 is inoculated into a culture medium and cultured to obtain seed liquid or fermentation liquid; (2) Mix the seed liquid or fermentation liquid with the oil to be treated thoroughly and culture it at a constant temperature of 25-40℃ to degrade malondialdehyde in the oil.

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