Compound microbial inoculant with adsorption function separated from sour soup, preparation method and application thereof

Abstract

The application discloses a composite microbial inoculant separated from sour soup and having an adsorption function, a preparation method and application thereof, and belongs to the technical field of microorganisms, and particularly relates to a composite microbial inoculant separated from sour soup and having an adsorption function, which comprises Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1, the preservation number of the Lactobacillus plantarum MJ-S1 is CCTCC NO: M 2026044, and the preservation number of the Lactobacillus casei MJ-P1 is CCTCC NO: M 2026043. The application discloses an application of the composite microbial inoculant in adsorbing microplastics. The composite microbial inoculant composed of the Lactobacillus plantarum MJ-S1 and the Lactobacillus casei MJ-P1 has a microplastic adsorption function and can be used for fermenting to prepare red sour soup with good flavor.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, and particularly relates to the preparation method and application of a composite bacterial agent with adsorption function isolated from sour soup. Background Technology

[0002] Microplastics refer to plastic particles with a diameter of less than 5 mm. Microplastics can exist in soil, freshwater, sediment, atmosphere, drinking water, and the human body. With soaring global plastic consumption and inadequate waste management, microplastic pollution has been rapidly propelled and is now widely distributed across all environments. Long-term exposure to microplastics poses potential risks to human health. Due to the presence of microplastics in plastic products, contact can occur through ingestion, inhalation, and skin contact, as well as through food and air. In all biological systems, microplastic exposure may lead to particulate toxicity, accompanied by oxidative stress, inflammatory lesions, and increased uptake or translocation, impacting human health.

[0003] In recent years, some patents in this field have mentioned the use of probiotics to adsorb microplastics. Although probiotics have a certain effect in adsorbing microplastics, the effect in probiotic compositions is limited. For example, publication number CN117089486 A, entitled "A strain of Lactobacillus plantarum DT55 and its application in the preparation of products with microplastic adsorption and removal functions," mentions Lactobacillus plantarum isolated from healthy human feces. Lactiplantibacillus plantarum DT55 can adsorb microplastics, but the effect of probiotic combination on the microplastic adsorption function is not mentioned; CN119372103A, "A plant lactobacillus MPs-68 with microplastic adsorption and uric acid degradation and its application", mentions plant lactobacillus MPs-68 isolated from marine products and Lactobacillus curvilinearis ( Latilactobacillus curvatus The product is a microplastic adsorbent composed of MPA01, but the specific ratio of the probiotic combination is not mentioned, and the combined strains used are Lactobacillus plantarum and Lactobacillus curvilinearis.

[0004] Microplastics, as widespread pollutants in the environment, can enter the human body through the food chain, posing a potential threat to the balance of the gut microbiota and host health. Studies have shown that certain probiotics can effectively capture and degrade microplastic particles through mechanisms such as biofilm encapsulation, surface adsorption, and extracellular polymeric binding, thereby reducing their retention and absorption in the gut. Furthermore, probiotics can indirectly reduce oxidative stress and inflammatory responses induced by microplastics by regulating intestinal barrier function and maintaining gut microbiota homeostasis. In food processing and environmental remediation, adding probiotics as biosorbents can bind microplastics before they are absorbed by the gut and excreted through feces, significantly inhibiting their toxic damage to the body. Therefore, screening probiotic strains with highly efficient microplastic adsorption capabilities holds significant application potential in environmental remediation and health protection. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a composite bacterial agent with adsorption function isolated from sour soup, its preparation method, and its application. The agent is composed of *Lactobacillus plantarum* (…). Lactiplantibacillus plantarum MJ-S1 and Lactobacillus casei ( Lacticaseibacillus casei The compound microbial agent composed of MJ-P1 has microplastic adsorption function and can be used to ferment and prepare flavorful red sour soup.

[0006] To achieve the above objectives, this invention provides a composite microbial agent with adsorption function isolated from sour soup. The composite microbial agent includes *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1. *Lactobacillus plantarum* MJ-S1 was deposited at the China Center for Type Culture Collection (CCTCC) on January 8, 2026, at Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026044. *Lactobacillus casei* MJ-P1 was also deposited at the same CCTCC on January 8, 2026, at Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026043.

[0007] Preferably, the mass ratio of *Lactobacillus plantarum* MJ-S1 to *Lactobacillus casei* MJ-P1 in the compound microbial agent is 2:1.

[0008] Preferably, the total number of effective viable bacteria in the compound microbial agent is ≥1×10⁻⁶. 10 CFU / mL.

[0009] The present invention also provides a method for preparing the compound microbial agent, comprising the following steps: mixing *Lactobacillus plantarum* MJ-S1 bacterial solution and *Lactobacillus casei* MJ-P1 bacterial solution at a mass ratio of 2:1 to prepare the compound microbial agent.

[0010] Preferably, the effective viable count of the *Lactobacillus plantarum* MJ-S1 bacterial suspension is 1 × 10⁻⁶.9 CFU / mL, the effective viable count of the *Lactobacillus casei* MJ-P1 bacterial suspension is 1×10⁻⁶ CFU / mL. 9 CFU / mL.

[0011] The present invention also provides the application of the composite microbial agent in the adsorption of microplastics.

[0012] Preferably, the microplastic is PS.

[0013] The present invention also provides the application of the composite microbial agent in the preparation of formulations with microplastic adsorption function, wherein the microplastic is PS.

[0014] The present invention also provides the application of the compound microbial agent in the preparation of red sour soup.

[0015] Preferably, the application specifically involves: taking chili peppers and tomatoes, breaking the cell wall, adding salt to obtain fermentation raw materials, inoculating the fermentation raw materials with compound microbial agent at an inoculation rate of 6% (v / v), and allowing it to ferment at 32°C for 7 days to obtain red sour soup.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] This invention provides a composite microbial agent with adsorption function isolated from fermented soup, composed of *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1. *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 were isolated from a homemade fermented soup sample from farmers in Majiang County, Guizhou Province. The composite microbial agent exhibits a significant adsorption effect on microplastics (PS) after being combined with *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1. Compared to single-strain bacteria, the composite microbial agent shows a significant synergistic effect in adsorbing microplastics (PS). In addition, the red sour soup prepared by fermentation with a compound microbial agent composed of Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 has a very popular flavor. The compound microbial agent improves the flavor of red sour soup, and the relative contents of volatile compounds such as esters, alkenes and alkanes in red sour soup are significantly increased. As the core flavor components, esters contribute typical aromas such as fruit and floral aromas. Alkenes present a fresh and citrusy fruity aroma. Although the contents of alkanes are low, they work synergistically with other flavor components, ultimately resulting in red sour soup prepared by the compound microbial agent producing more kinds of volatile flavor substances as a whole. Moreover, it shows a significant advantage in the content of key flavor components compared with the naturally fermented control group. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a colony diagram of *Lactobacillus plantarum* MJ-S1.

[0020] Figure 2 Phylogenetic tree of Lactobacillus plantarum MJ-S1;

[0021] Figure 3 This is a colony diagram of Lactobacillus casei MJ-P1.

[0022] Figure 4 Phylogenetic tree of Lactobacillus casei MJ-P1;

[0023] Figure 5 Acid resistance determination for Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1;

[0024] Figure 6 The bile salt tolerance of Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 was determined.

[0025] Figure 7 To determine the survival ability of Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 in simulated intestinal fluid;

[0026] Figure 8 To determine the survival ability of Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 in simulated gastric juice;

[0027] Figure 9 The adsorption effect of *Lactobacillus plantarum* MJ-S1, *Lactobacillus casei* MJ-P1, and compound microbial agent on microplastics was determined. Among them, A is the blank group, B is the *Lactobacillus plantarum* MJ-S1 group, C is the *Lactobacillus casei* MJ-P1 group, and D is the compound microbial agent group.

[0028] Figure 10 Microscopic observation of the precipitation after the compound bacterial agent adsorbs microplastics;

[0029] Figure 11 Red sour soup prepared by fermentation with compound microbial agents;

[0030] Figure 12 It is a naturally fermented red sour soup.

[0031] Preservation Information

[0032] Lactobacillus plantarum MJ-S1, Latin name Lactiplantibacillus plantarum Its taxonomic name is Lactobacillus plantarum MJ-S1 Lactiplantibacillus plantarum MJ-S1 strain is deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, on January 8, 2026, with accession number CCTCC NO:M 2026044.

[0033] Lactobacillus casei MJ-P1, Latin name Lacticaseibacillus casei Its taxonomic name is Lactobacillus casei MJ-P1 Lacticaseibacillus casei The strain MJ-P1 is deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, on January 8, 2026, with accession number CCTCC NO:M2026043. Detailed Implementation

[0034] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, for numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within the scope of the invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. While only preferred methods and materials are described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of the invention. All references to this specification are incorporated by reference to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary. The terms "comprising," "including," "having," "containing," etc., as used herein are open-ended, meaning they include but are not limited to.

[0035] The materials used in this invention were sourced from the following sources: Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 were isolated from fermented sour soup samples made by farmers in Majiang County, Guizhou Province; the DNA kit, liquid MRS medium and PBS buffer were purchased from Sangon Biotech (Shanghai) Co., Ltd.

[0036] Example 1

[0037] Isolation and identification of strains: On the day of sampling from the sour soup, the sample was temporarily stored in a 4℃ refrigerator. In a clean bench, 5 mL of the sample was aseptically aspirated and placed into an Erlenmeyer flask containing 45 mL of sterile physiological saline. The mixture was thoroughly mixed in a shaker for 5 min to prepare a 1:10 serial dilution homogenate, at which point the concentration was 10. -1 Accurately pipette 1 mL of 10 mL of liquid. -1 The diluted sample was placed in 9 mL of sterile physiological saline, vortexed for 1 min, and the serial dilution steps were repeated to serially dilute the sample to the bacterial suspension.

[0038] DNA identification was performed on the strain initially determined to be pure culture. The strain was first activated and expanded, and the DNA extraction procedure was followed according to the DNA kit instructions. The specific detection method is as follows: Take 1-1.5 mL of bacterial culture cultured for 12 h, centrifuge at 4500 rpm for 5 min, discard the supernatant, add 180 μL of lysozyme to the bacterial slurry, incubate at 37℃ for 1 h, inverting and mixing every 10 min. Then add 400 μL of buffer digestion solution, mix well, and incubate at 65℃ for 1 h, inverting and mixing every 10 min. After complete lysis, add 200 μL of PB buffer, mix by pipetting, and incubate at -20℃ for 5 min to allow for complete reaction. After the reaction is complete, centrifuge at 10000 rpm for 5 min, take 500 μL of the supernatant, add an equal volume of isopropanol, mix by pipetting, and incubate at room temperature for 3 min. Centrifuge at 10000 rpm for 5 min, discard the supernatant, and retain the solid. Add 1 mL of 75% ethanol to the tube, mix well by pipetting, centrifuge at 10,000 rpm for 2 min, discard the supernatant, repeat twice, and allow the residual ethanol to evaporate completely at room temperature for 5 min with the cap open. Dissolve in 50-100 μL of TE buffer to obtain the extracted DNA, and store at 4℃.

[0039] Table 1 16S rDNA amplification system

[0040]

[0041] The 16S rDNA amplification system is shown in Table 1: Lactic acid bacteria DNA was used as the PCR amplification template, with a total volume of 50 μL; the nucleotide sequence of the 16SF upstream primer (27F) was 5'-AGAGTTTGATCCTGGCTCAG-3' (SEQ ID NO.3); the nucleotide sequence of the 16SR downstream primer (1492R) was 5'-GGCTACCTTGTTACGACT-3' (SEQ ID NO.4). PCR amplification conditions: 95℃ pre-denaturation for 5 min, 94℃ denaturation for 1 min, 55℃ annealing for 1 min, 72℃ extension for 3 min, for a total of 30 cycles, with a final extension at 72℃ for 10 min, and incubation at 16℃ for 1 h.

[0042] Colony characteristics of strain MJ-S1 are as follows Figure 1 As shown, the phylogenetic tree is as follows: Figure 2 As shown, strain MJ-S1 was identified as *Lactobacillus plantarum*, with the Latin name: Lactiplantibacillus plantarum It was named MJ-S1. The colony characteristics of strain MJ-P1 are as follows: Figure 3 As shown, the phylogenetic tree is as follows: Figure 4 As shown, strain MJ-P1 was identified as *Lactobacillus casei*, with the Latin name: Lacticaseibacillus casei They named it MJ-P1.

[0043] The sequencing results were searched for similar sequences in the NCBI database using Blast software. The sequences of strains MJ-S1 and MJ-P1 were compared with the 16S rRNA gene sequences of related species obtained from the gene bank. The 16S rRNA gene sequencing results are as follows: The nucleotide sequence of the 16S rRNA of strain MJ-S1 is shown in SEQ ID NO.1. The nucleotide sequence of the 16S rRNA of strain MJ-P1 is shown in SEQ ID NO.2.

[0044] Activated strains: Take bacterial suspensions of strains MJ-S1 and MJ-P1 stored at -80℃, and inoculate them into liquid MRS medium at 4% (v / v). Place them in an incubator at 37℃ and let them stand for 24 hours. Repeat the operation twice to obtain activated culture solutions of strains MJ-S1 and MJ-P1 for use in experiments.

[0045] Acid tolerance test: A low pH environment significantly inhibits the growth of probiotics. The strains must not only tolerate the low pH environment of fermentation but also the acidic environment of the human stomach. The pH of human stomach acid is typically around 3.0, lower than the pH during the fermentation process of sour soup. Therefore, it is necessary to screen for strains with strong acid tolerance to better exert their beneficial effects on the human body.

[0046] 1 mL of each of the activated cultures of strains MJ-S1 and MJ-P1 were centrifuged at 4500 rpm, 4℃, for 5 min to collect the bacterial cells. The cells were resuspended in liquid MRS culture medium at pH 3.0 and 3.5, respectively. The suspensions were then incubated at 37℃. Samples were taken at 0 h and 3 h, and the viable cell count was calculated using the dilution-spreading method. Using strains inoculated in ordinary liquid MRS culture medium as a control, the survival rate of the strains under different acidic conditions was determined. Three independent experiments were performed, and the average value was taken. The formula for calculating the strain survival rate is: Strain survival rate (%) = N t / N0×100%, where N t N is the colony count after 3 hours, and N0 is the colony count after 0 hours.

[0047] The results are as follows Figure 5 As shown, after 3 hours of culture in a gradient acidic medium, the survival rates of *Lactobacillus plantarum* MJ-S1 in liquid MRS culture media at pH 3.0 and 3.5 were 62.14% and 52.36%, respectively; the survival rates of *Lactobacillus casei* MJ-P1 in liquid MRS culture media at pH 3.0 and 3.5 were 83.38% and 74.03%, respectively. Although the survival rate of the strains decreased after the pH gradient was changed, the survival rates of *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 remained relatively high, indicating that both *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 have strong acid resistance and can survive in the gastric environment.

[0048] Bile salt tolerance test: Probiotics in the intestines face the stress of bile salts, which can damage cell membrane structure, inhibit bacterial growth, and potentially cause death. Given that bile salts are mainly distributed in the small intestinal fluid, the survival and function of probiotics are highly dependent on their tolerance to bile salts.

[0049] 1 mL of each of the activated cultures of strains MJ-S1 and MJ-P1 were centrifuged at 4500 rpm, 4℃, for 5 min to collect the bacterial cells. These cells were then inoculated into MRS culture media with bile salt concentrations of 0.2% and 0.3%, respectively, and resuspended. The bacterial suspensions were incubated at 37℃. Samples were taken at 0 h and 3 h, and the viable cell count was calculated using the dilution-spreading method. The survival rate of the strains under different bile salt concentrations was determined, with the strains inoculated in ordinary liquid MRS culture media serving as a control. Three independent experiments were performed, and the average value was taken. The formula for calculating the strain survival rate is: Strain survival rate (%) = N t / N0×100%, where N t N is the colony count after 3 hours, and N0 is the colony count after 0 hours.

[0050] The results are as follows Figure 6As shown, after 3 hours of culture in a gradient bile salt medium, the survival rates of *Lactobacillus plantarum* MJ-S1 were 113.49% and 75.43%, respectively, while the survival rates of *Lactobacillus casei* MJ-P1 were 88.43% and 55.33%, respectively. After the bile salt concentration gradient was changed, the survival rate of the strains showed a decreasing trend. *Lactobacillus plantarum* MJ-S1 had a higher survival rate, indicating that the strains had considerable bile salt tolerance and could survive in the small intestine.

[0051] Intestinal fluid resistance test: 1 mL of activated culture medium for strains MJ-S1 and MJ-P1 was taken from each strain and centrifuged at 4500 rpm, 4℃ for 5 min to collect the bacterial cells. These cells were then inoculated into simulated intestinal fluid and resuspended. The bacterial suspensions were incubated at 37℃, 150 rpm in a constant temperature window. Samples of the simulated intestinal fluid were taken at 0 h, 3 h, and 6 h. The viable cell count was calculated using the dilution-spreading method to determine the survival rate of the strains in the simulated gastrointestinal fluid. Three independent experiments were repeated, and the average value was taken. Strain survival rate formula: Strain survival rate (%) = N t / N0×100%, where N t N is the colony count after 3 hours or 6 hours, and N0 is the colony count after 0 hours.

[0052] The results are as follows Figure 7 As shown, after 3-6 hours of culture in simulated intestinal fluid, the survival rates of *Lactobacillus plantarum* MJ-S1 were 47.41% and 85.85%, respectively, while the survival rates of *Lactobacillus casei* MJ-P1 were 42.94% and 136.74%, respectively. The survival rates of the strains showed an increasing trend over time. The high survival rates of *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 indicate that they exhibit significant tolerance to the high bile salt environment and trypsin activity in the intestine, and can effectively survive in simulated intestinal fluid.

[0053] Gastric fluid resistance test: 1 mL of activated culture medium for strains MJ-S1 and MJ-P1 was taken from each strain and centrifuged at 4500 rpm, 4℃ for 5 min to collect the bacterial cells. These cells were then inoculated into simulated gastric fluid and resuspended. The bacterial suspensions were incubated at 37℃, 150 rpm in a constant temperature window. Samples of the simulated gastric fluid were taken at 0 h and 3 h. The viable cell count was calculated using the dilution-spreading method to determine the survival rate of the strains in the simulated gastrointestinal fluid. Three independent experiments were repeated, and the average value was taken. Strain survival rate formula: Strain survival rate (%) = N t / N0×100%, where N t N is the colony count after 3 hours, and N0 is the colony count after 0 hours.

[0054] The results are as follows Figure 8As shown, after 3 hours of culture in simulated gastric juice medium, the 3-hour survival rate of *Lactobacillus plantarum* MJ-S1 was 84.49%, and that of *Lactobacillus casei* MJ-P1 was 86.96%. With the passage of time, the survival rate of the strains showed an increasing trend. The high survival rates of *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 indicate that they can effectively resist the erosion of acid and pepsin and exhibit good survival ability under simulated gastric juice conditions.

[0055] Example 2

[0056] Lactobacillus plantarum MJ-S1 and Lactobacillus casei MJ-P1 were inoculated into liquid MRS medium and cultured anaerobically at 37°C for 18 h. The cultured bacterial suspensions were centrifuged at 2000 rpm for 10 min, the supernatant was discarded, and each suspension was washed twice with 450 μL of sterile PBS buffer. The suspensions were then resuspended in PBS buffer, and the bacterial concentration was adjusted to 1 × 10⁻⁶. 9 CFU / mL, *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 bacterial suspensions were obtained, respectively. The *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 bacterial suspensions were mixed at a mass ratio of 2:1 to prepare a compound bacterial agent. The effective viable count of the compound bacterial agent was ≥1×10⁻⁶. 10 CFU / mL.

[0057] Experimental Example 1

[0058] Adsorption effect of microplastics: 100 μL each of the *Lactobacillus plantarum* MJ-S1 bacterial suspension, *Lactobacillus casei* MJ-P1 bacterial suspension, and the composite bacterial agent prepared in Example 2 were added to 1.5 mL EP tubes. 900 μL of PS fluorescent microsphere working solution (0.16 mg / mL, particle size 5 μm, Basel) was added to each tube, and the mixture was incubated on a shaker in the dark for 4 h at 37°C and 300 rpm. For the blank control group, 100 μL of PBS buffer was added to 900 μL of PS fluorescent microsphere working solution, and the mixture was incubated on a shaker in the dark for 4 h at 37°C and 300 rpm. After incubation, the incubation solution was observed and photographed.

[0059] Take the incubation solution from each group, centrifuge at 2000 rpm for 10 min, and take 100 μL of supernatant from each group. Measure the fluorescence intensity using a microplate reader. The microplate reader parameters are: excitation wavelength 494 nm; detection wavelength 518 nm. Calculate the adsorption rate based on the fluorescence intensity values. The formula for calculating the adsorption rate is: Adsorption rate (%) = (A1 - A2) / A1 × 100% (A1: fluorescence value of the blank group, A2: fluorescence value of each bacterial agent group).

[0060] The results are as follows Figure 9 China A Figure 9B, Figure 9 C and Figure 9 As shown in Figure D, in the blank group, the PS fluorescent microspheres did not self-aggregate. In each bacterial agent group, the bacteria and PS fluorescent microspheres showed specific adsorption and agglomeration of flocculent matter. The adsorption rate of *Lactobacillus plantarum* MJ-S1 reached 76.13%, and that of *Lactobacillus casei* MJ-P1 reached 75.51%, both strains exhibiting strong adsorption capacity for microplastics. This indicates that the adsorption effect of *Lactobacillus plantarum* MJ-S1 and *Lactobacillus casei* MJ-P1 on microplastics is strain-specific. The adsorption rate of the compound bacterial agent was 94.49%, and the adsorption effect of the compound bacterial agent was significantly different from that of individual probiotics.

[0061] After centrifugation, the precipitate from the compound bacterial agent group was fixed overnight with glutaraldehyde at 4°C, then dehydrated using a gradient of ethanol, dried, and observed under an electron microscope. Figure 10 As shown, the compound microbial agent group exhibits significant specific adsorption and aggregation of flocculent matter, further demonstrating the good adsorption effect of the compound microbial agent.

[0062] Experimental Example 2

[0063] Mix 500g of chili peppers and 500g of tomatoes, along with 5g of garlic and 5g of ginger. Break down the cell wall, add 30g of salt, and stir thoroughly to obtain the fermentation raw material. Inoculate the fermentation raw material with the compound microbial agent prepared in Example 2 at a 6% (v / v) inoculation rate. Add white wine to the top layer for sealing, and let it ferment at 32℃ for 7 days to obtain red sour soup (e.g., Figure 11 ).

[0064] Natural fermentation: Mix 500g of chili peppers and 500g of tomatoes, along with 5g of garlic and 5g of ginger. Blend them together, add 30g of salt, and stir thoroughly to obtain the fermentation ingredients. Add white wine to the top layer to seal the mixture. Transfer it to an earthenware jar for fermentation for 3 months without opening the lid or stirring. This will produce naturally fermented red sour soup (such as...). Figure 12 ).

[0065] The composition and content of flavor compounds are key indicators for evaluating the quality of fermented foods. In the fermentation system of red sour soup, microorganisms transform substrates into diverse flavor components through metabolic activities, giving the product its unique flavor characteristics.

[0066] Table 2 Volatile Compounds

[0067]

[0068]

[0069]

[0070] As shown in Table 2, 85 volatile compounds were identified in the samples of red sour soup fermented with compound microbial agents and naturally fermented red sour soup using gas chromatography-mass spectrometry (GC-MS). The volatile flavor compounds in both groups of red sour soup were dominated by alcohols, esters, and alkenes, with alcohols being the most abundant. Alcohols can react with organic acids through esterase catalysis to form esters, or combine with glycerides and acetyl-CoA under the action of acyltransferases / esterases to form ester compounds. The experiment showed that the relative contents of esters, alkenes, and alkanes were significantly increased in the compound microbial agent fermentation group: esters, as core flavor components, contributed typical aromas such as fruit and floral notes; alkenes exhibited a fresh, citrus-like fruity aroma; although alkanes were present in lower amounts, they synergistically interacted with other flavor components, ultimately leading to a significant difference in overall flavor between the compound microbial agent fermentation group and the naturally fermented group. This combination not only produces a wider variety of volatile flavor compounds, but also shows a significant advantage over the naturally fermented group in terms of the content of key flavor components.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A compound microbial agent with adsorption function isolated from sour soup, characterized in that, The compound microbial agent includes *Lactobacillus plantarum* (… Lactiplantibacillus plantarum MJ-S1 and Lactobacillus casei ( Lacticaseibacillus casei MJ-P1; The *Lactobacillus plantarum* MJ-S1 was deposited at the China Center for Type Culture Collection (CCTCC) on January 8, 2026, at Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026044. The Lactobacillus casei MJ-P1 was deposited at the China Center for Type Culture Collection (CCTCC) on January 8, 2026, at Wuhan University, Wuhan, China, with accession number CCTCC NO:M 2026043.

2. The compound microbial agent according to claim 1, characterized in that, The mass ratio of *Lactobacillus plantarum* MJ-S1 to *Lactobacillus casei* MJ-P1 in the compound microbial agent is 2:

1.

3. The compound microbial agent according to claim 1, characterized in that, The total number of effective viable bacteria in the compound microbial agent is ≥1×10⁻⁶. 10 CFU / mL.

4. The method for preparing the compound microbial agent according to any one of claims 1 to 3, characterized in that, Includes the following steps: A compound bacterial agent was prepared by mixing Lactobacillus plantarum MJ-S1 bacterial solution and Lactobacillus casei MJ-P1 bacterial solution at a mass ratio of 2:

1.

5. The preparation method according to claim 4, characterized in that, The effective viable count of the *Lactobacillus plantarum* MJ-S1 bacterial suspension was 1×10⁻⁶. 9 CFU / mL, the effective viable count of the *Lactobacillus casei* MJ-P1 bacterial suspension is 1×10⁻⁶ CFU / mL. 9 CFU / mL.

6. The application of the composite microbial agent as described in any one of claims 1 to 3 in the adsorption of microplastics, characterized in that, The microplastic is PS.

7. The application of the composite microbial agent according to any one of claims 1 to 3 in the preparation of formulations with microplastic adsorption function, characterized in that, The microplastic is PS.

8. The application of the compound microbial agent as described in any one of claims 1 to 3 in the preparation of red sour soup.

9. The application according to claim 8, characterized in that, The specific application is as follows: take chili peppers and tomatoes, break the cell wall, add salt to obtain fermentation raw materials, inoculate the compound bacterial agent into the fermentation raw materials at an inoculation rate of 6% (v / v), and let it ferment at 32℃ for 7 days to obtain red sour soup.

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