Lactobacillus strain for inhibiting biofilm and application thereof in food fermentation

Abstract

This application belongs to the field of microbial technology and relates to a strain of lactobacillus that inhibits biofilms and its application in food fermentation. This invention discloses a strain of *Lactobacillus brevis* with biofilm-inhibiting ability (…). Lentilactobacillus buchneri This invention relates to strain L4 and its application in food fermentation. This strain is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC M2026240, dated January 26, 2026. The L4 strain provided by this invention achieves highly efficient inhibition of blastocyst yeasts through multiple mechanisms, including acid production, bacteriocin production, and competitive exclusion. It simultaneously achieves rapid acidification, flavor substance accumulation, active ingredient enrichment, and spoilage bacteria control, solving the core problems of mold growth and unstable quality in traditional sour soup fermentation. This provides an excellent dedicated strain and effective method for the standardized, safe, and industrialized production of sour soup.

Description

Technical Field

[0001] This application belongs to the field of microbial technology and relates to a strain of lactobacillus that inhibits biofilms and its application in food fermentation. Background Technology

[0002] Sour soup is a traditional fermented fruit and vegetable food, made from rice, vegetables, and other ingredients through fermentation by microorganisms such as lactic acid bacteria. It has a unique sour taste and flavor, making it popular with consumers. Traditional sour soup relies heavily on natural fermentation, resulting in a complex microbial community that is susceptible to contamination by environmental microorganisms. The formation of biofilms is the most common and widespread phenomenon. Pichia membranifaciens, a biofilm-producing yeast, is the most prevalent genus producing biofilms. Excessive proliferation of this yeast during fermentation can lead to a deterioration in the flavor of the sour soup, the development of unpleasant odors, reduced product quality, and even food safety issues. This yeast forms a grayish-white film on the surface of the sour soup, affecting not only sensory quality but also potentially secreting fungal toxins that threaten human health. Current control methods largely rely on chemical preservatives or physical methods. However, chemical preservatives easily destroy the natural flavor and nutritional components of the sour soup, and long-term use poses safety risks. Physical methods (such as ultraviolet light and heat treatment) are difficult to use precisely without affecting the fermentation system and often only address the symptoms, not the root cause. Against this backdrop, a biological control strategy of "controlling bacteria with bacteria and using bacteria for biological prevention" has emerged. The Lactobacillus strain obtained by screening in this invention is a typical application of this concept. This strain does not rely on the addition of antibacterial substances externally, but rather utilizes the natural competitive relationship between microorganisms to significantly inhibit the growth of film-producing yeasts such as Pichia pastoris through multiple mechanisms such as acid production, bacteriocin production, and competitive exclusion, without affecting the original fermentation characteristics and flavor formation of the sour soup.

[0003] Currently, most sour soup production uses natural fermentation or mixed-strain fermentation, with few specialized strains specifically designed to inhibit harmful yeasts. For example, Chinese invention patent CN110699273B (by Wu Duqin et al.) discloses a strain of *Lactobacillus casei* LHZ-ST-002 (accession number CGMCC NO.16447) and its application in sour soup fermentation. This patent, "A *Lactobacillus casei* and its application," reports that using *Lactobacillus casei* to prepare sour soup results in a sour soup with an acidity 1.2–1.9 times higher than commercially available sour soup fermented with ordinary *Lactobacillus casei*. However, its fermentation time is only 10–15 days, which cannot guarantee the stability and safety of subsequent fermentation. This patent, after inoculating with L4 bacterial solution, does not produce a biofilm after 20 days of fermentation. It can effectively extend shelf life and enhance flavor and taste. Patent CN 117778207 A (A biofilm-producing yeast such as *Pichia pastoris* and its application in the enhanced fermentation of tomato sour soup) proposes using biofilm-producing yeasts such as *Pichia pastoris* (… Pichia membranifaciensThis type of yeast, *Pichia helmetii*, is used as an enhanced fermentation strain in tomato sour soup fermentation, and is believed to contribute significantly to both sourness and saltiness. However, film-forming yeasts such as *Pichia helmetii* have a dual role in the fermentation process: in the early stages of fermentation or during well-controlled short-term fermentation (e.g., 5–7 days), their metabolites may contribute to flavor formation; but as fermentation time increases (≥10 days), this yeast easily forms a grayish-white film (i.e., "flowering") on the liquid surface, and metabolizes to produce undesirable flavor substances, and may even secrete fungal toxins, leading to product spoilage. The patent titled "A Film-Forming Yeast such as *Pichia helmetii* and its Application in Enhanced Fermentation of Tomato Sour Soup" only ferments the sour soup for 4–6 days, and the subsequent film-forming issue is not addressed.

[0004] Therefore, screening a lactobacillus strain that can both promote the normal fermentation of sour soup and effectively inhibit biofilm formation is of great significance for achieving standardized and safe production of sour soup. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a strain of Lactobacillus (L4) that inhibits biofilm formation, as detailed below: A strain of Lactobacillus that inhibits biofilms is deposited at the China Center for Type Culture Collection (CCTCCM2026240) on January 26, 2026.

[0006] The Lactobacillus brucellosis L4 has the following characteristics: (1) Morphological characteristics: The bacteria are rod-shaped, Gram-positive, and catalase-negative.

[0007] (2) Culture characteristics: It grows well in MRS liquid medium, with an optimal growth temperature of 30-37℃ and an optimal pH of 5.5-6.5.

[0008] (3) Core functional characteristics: It has a strong inhibitory effect on film-producing yeasts such as Pichia pastoris, which cause spoilage of red sour soup. According to the Oxford cup method, the diameter of the inhibition zone of its sterile fermentation supernatant against strain pMY-S2 can reach 18.85±0.18 mm, and the antibacterial effect is significantly better than other common lactobacilli.

[0009] Furthermore, the lactobacillus that inhibits biofilm formation is *Lactobacillus brevis* (…). Lentilactobacillus buchneri ), whose strain number is L4.

[0010] Furthermore, the biofilm-inhibiting lactobacillus has rod-shaped cells, is Gram-positive, and negative for catalase.

[0011] The application of the biofilm-inhibiting lactobacilli in sour soup fermentation.

[0012] Furthermore, the application involves adding activated Lactobacillus brevis L4 cells or its fermentation broth as a starter culture to the sour soup fermentation system.

[0013] The specific application method is as follows: Lactobacillus brucellosis L4 is activated in MRS liquid medium until the viable count is ≥1×10⁴. 8 CFU / mL, at an inoculation rate of 1%-5% of the total weight of the fermentation raw materials, is inoculated into the red sour soup fermentation substrate (mainly including chili peppers, tomatoes, salt, ginger, garlic, glutinous rice, etc.), and fermented at 30-37℃ for 5-30 days.

[0014] Furthermore, the application in sour soup fermentation is an application to inhibit harmful yeast contamination during the sour soup fermentation process.

[0015] Furthermore, the aforementioned harmful yeast contamination refers to harmful yeasts that produce biofilms, especially biofilm-producing yeasts such as Pichia pastoris.

[0016] Furthermore, the sour soup mentioned is Guizhou fermented sour soup.

[0017] Furthermore, the Guizhou fermented sour soup is obtained by fermenting chili peppers, tomatoes, ginger, and garlic as the main raw materials.

[0018] The beneficial effects of this application are: (1) This invention discloses a strain of *Lactobacillus brucellosis* with the ability to inhibit biofilm formation. Lentilactobacillus buchneri L4 and its application in fermented red sour soup. This strain is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC M2026240 and deposit date of January 26, 2026. Strain L4 was isolated from a high-quality fermented red sour soup sample and obtained through antagonistic screening against eight putrefactive bacteria (all identified as film-producing yeasts such as *Pichia pastoris*). Oxford cup assay showed that the inhibition zone diameter of the aseptic fermentation supernatant of L4 against the putrefactive bacterium pMY-S2 reached 18.85 ± 0.18 mm, demonstrating a significantly superior antibacterial effect compared to other tested lactobacilli. When L4 was applied at a 3% inoculum for enhanced fermentation of red sour soup, it exhibited multiple synergistic effects: within 2 days of fermentation, the pH of the system rapidly decreased to 3.49±0.01 and remained stable; the peak total acid content reached 16.670 g / kg, and the peak amino acid nitrogen content reached 11.288 mg / 100g, significantly higher than that of the naturally fermented group; the reducing sugar content rapidly decreased to 0.063 mg / g in the first 3 days and stabilized at around 0.043 mg / g after day 4, demonstrating its highly efficient sugar metabolism rate; in terms of active ingredients, the total phenols, total flavonoids, and vitamin C reached 3.611 mg GAE / g, 9.028 mg / 100g, and 14.796 mg / 100g, respectively, far exceeding those of the naturally fermented group; in terms of antibacterial ability, the fungal colony count in the L4 group remained below 1.0×10⁻⁶ within 17 days of fermentation.1 CFU / mL, with no "flowering" or budding membrane phenomenon throughout the entire process, while the naturally fermented group showed obvious budding membrane on day 14, and the fungal colony count reached as high as 1.88 × 10⁻⁶ on day 17. 6 CFU / mL. The strain L4 provided by this invention achieves highly efficient inhibition of film-producing yeasts such as Pichia pastoris through multiple mechanisms including acid production, bacteriocin production, and competitive exclusion. It simultaneously completes rapid acidification, flavor substance accumulation, active ingredient enrichment, and spoilage bacteria control, solving the core problems of easy "mold formation" and unstable quality in traditional sour soup fermentation. It provides an excellent dedicated strain and effective strategy for the standardized, safe, and industrialized production of sour soup.

[0019] (2) The enhanced fermentation using Lactobacillus brevis L4 provided by this invention can produce the following synergistic and beneficial effects: ① Highly effective inhibition of spoilage and improved product stability: L4 can effectively inhibit the growth of spoilage yeast, completely prevent the "flowering" and film formation on the product surface during the fermentation process and shelf life, avoid abnormal pH increases and loss of flavor acids caused by excessive consumption of organic acids by yeast, and significantly reduce the risk of spoilage such as product bloating and off-flavor. ② Dominate the fermentation process and improve quality indicators: L4 can quickly start fermentation, rapidly reduce the pH of the system, and the total acid content is significantly higher than that of the naturally fermented group, making the product have a pure and rich sour taste. At the same time, it can improve the level of umami substances such as amino acid nitrogen in the product. ③ Enrichment of active ingredients and enhancement of nutritional function: Compared with natural fermentation, the content of antioxidant active ingredients such as total phenols, total flavonoids, and vitamin C in red sour soup fermented with L4 is significantly increased, enhancing the nutritional and health value of the product. Attached Figure Description

[0020] Figure 1 This image shows the antibacterial effect of Lactobacillus brevicornu L4 of this invention against putrefactive bacteria.

[0021] Figure 2 This is the phylogenetic tree of Lactobacillus brucellosis L4 of the present invention.

[0022] Figure 3 These are colony morphology photos and cell morphology photos of Lactobacillus brucei L4 of the present invention.

[0023] Figure 4 This is a comparison chart of the total bacterial count in red sour soup at different fermentation times between the Lactobacillus brevis L4 fermentation group and the naturally fermented group of this invention.

[0024] Figure 5 This is a diagram showing the results of fermenting red sour soup with Lactobacillus brevicornu L4 according to the present invention.

[0025] Figure 6 This is a comparison chart of the total phenols, total flavonoids, and vitamin C content of the L4 fermentation group and the naturally fermented group of *Lactobacillus brevicornu* at different fermentation times.

[0026] Figure 7 This is a diagram illustrating the natural fermentation process of the red sour soup of this invention. Detailed Implementation

[0027] The present application will be further described in detail below with reference to specific embodiments. The description is for explanation and not limitation of the present application.

[0028] Example 1: Screening for inhibiting putrefactive yeast Lactobacillus Eleven strains of Lactobacillus with strong fermentation performance and inhibitory effect on putrefactive bacteria were screened from high-quality fermented sour soup samples. The screening was performed using both the double-layer plate method and the Oxford cup method. The eleven Lactobacillus strains were inoculated into MRS medium and activated twice. Using an inoculation loop, a 2 cm "+" shape was drawn in the center of the MRS agar medium, and the medium was incubated at 37℃ for 24 h. The Lactobacillus grew in the "+" shape. A suspension of indicator bacteria (six putrefactive yeast strains screened from abnormal sour soup samples) was inoculated at 2% onto 5 mL of PDB soft agar medium (0.7% agar), mixed well, and poured onto the MRS agar medium containing the "+" Lactobacillus strains. After solidification, the medium was incubated at 30℃, with three replicates per group, for 48 h. Figure 1 The Oxford cup method involves mixing the indicator bacteria suspension with 50°C PDB soft agar medium, pouring the mixture onto a plate containing Oxford cups, and removing the cups after the medium has cooled. 100 μL of Lactobacillus culture supernatant is then added to each well. MRS broth is used as a control group. The plates are incubated at 30°C for 24 hours. The diameter of the opaque circle around each well is measured using calipers. The experiment is repeated three times, and the size of the inhibition zone reflects the inhibitory effect on Lactobacillus. Figure 1 Ultimately, strain L4 was found to have the best inhibitory effect on the six putrefactive bacteria, as shown in Table 3. Among them, L4 had the largest inhibition zone diameter against the putrefactive bacterium pMY-S2 (18.85±0.18 mm) and the smallest inhibition zone diameter against the putrefactive bacterium pMY-Y (14.00±0.08 mm, with an Oxford cup well diameter of 8.0 mm).

[0029] Example 2 Identification of L4 strain Systematic molecular biological and classical microbiological identification of strain L4 was performed. First, genomic DNA was extracted from the strain, and its 16S rRNA gene was amplified using universal primers and sequenced. The sequence was then aligned using BLAST and analyzed using a phylogenetic tree. The results (…) Figure 2 The results showed that strain L4 was similar to *Lactobacillus brucellosis* (…). Lentilactobacillus buchneri The standard strains clustered together, showing a homology higher than 99%, and were therefore tentatively identified as *Lactobacillus brucellosis*. Gram staining microscopy showed ( Figure 3 This strain is a Gram-positive short rod-shaped bacterium, non-spore-forming, and usually found singly or in pairs; it forms small, milky-white colonies with neat edges on MRS solid medium. Physiological and biochemical identification shows that it is catalase-negative, does not produce indole or hydrogen sulfide (H2S), and is negative for nitrate reduction.

[0030] Example 3: Application of the dominant inhibitory bacterium L4 Inoculate L4 at 2%–5% to ferment red sour soup, with a chili:tomato ratio of 1:5–5:1, and add 2%–10% of ginger, garlic, salt, and glutinous rice. Ferment at 35℃, and take samples for analysis on days 1, 2, 3, 4, 5, 7, 10, and 14.

[0031] 3.1 Determination of physicochemical properties The pH of the samples was determined using a Leici PHS-3C handheld pH meter; the total acid of the samples was determined according to GB12456-2021 Determination of Total Acid in Food (Acid-Base Titration Method); the amino acid nitrogen of the samples was determined according to GB 5009.235-2016 Determination of Amino Nitrogen in Food (Acidity Meter Method); the reducing sugar of the samples was determined according to NY / T 2742—2015 Determination of Soluble Sugars in Fruits and Fruit Products - 3,5-Dinitrosalicylic Acid Colorimetric Method; the soluble solids were determined using an HP-TD32 handheld digital refractometer; and the nitrite of the samples was determined according to GB 5009.33-2016 Determination of Nitrite and Nitrate in Food (Spectrophotometric Method).

[0032] The L-4 fermentation group rapidly produced acid within 2 days, causing the system pH to drop quickly to the 3.4–3.5 range and stabilize, before slightly recovering after 7 days of fermentation. The total acid (TTA) content peaked on day 7 (16.670 g / kg), then decreased to 13.583 g / kg. The higher acidity helped inhibit the growth of contaminating microorganisms, thus improving product quality. The amino acid nitrogen (AAN) content in the L-4 group showed a trend of first decreasing and then increasing: AAN reached its lowest value on day 4 (3.783 mg / 100g), then gradually increased to 11.288 mg / 100g on day 10; this change indicates that microorganisms consumed nitrogen sources for growth and reproduction in the early stages of fermentation, while enzymatic hydrolysis increased in the later stages, leading to increased AAN accumulation. Regarding carbon source utilization, the reducing sugar (RS) content in the L-4 group dropped sharply in the first 3 days, stabilizing at around 0.043 mg / g after day 4, indicating a rapid metabolic rate and good acid-generating effect. Changes in soluble solids (SS) and reducing sugars together influence the flavor formation and microbial metabolic dynamics of the product.

[0033] Table 1 Physicochemical properties of L-4 fermented red sour soup

[0034] 3.2 Determination of active ingredients Total phenols in the samples were determined using the Folin-Ciocalteu colorimetric method. 2.0 g of the sample was weighed and extracted with 10 mL of 70% ethanol by ultrasonic extraction for 30 min, followed by centrifugation at 6000 r / min for 8 min. The resulting solution was used as a test solution. The absorbance at 765 nm was measured, a standard curve was plotted, and the content (expressed as gallic acid equivalent, GAE) was calculated. The total flavonoid content in the samples was determined according to the method of Dewanto et al. (Dewanto et al., 2002). The vitamin C content in the samples was determined according to the 2,6-dichlorophenolindophenol titration method in GB 5009.86-2016.

[0035] The results showed that L4 Lactobacillus fermentation effectively enhanced the enrichment of active ingredients in red sour soup. The contents of total phenols, total flavonoids, and vitamin C exhibited dynamic changes during the fermentation cycle. The total phenol content in the L4 fermentation group initially increased and then fluctuated during fermentation, reaching a peak of 3.611 mg GAE / g on day 4. The total flavonoid content accumulated rapidly in the early stages of fermentation, reaching a maximum of 9.028 mg / 100 g on day 3, and then gradually decreased with increasing fermentation time, continuing to decline after day 4, stabilizing at a certain level from day 7 until the end of fermentation. The vitamin C content remained at a high level throughout the fermentation process, showing a fluctuating upward trend followed by a decline, reaching a maximum of 14.796 mg / 100 g on day 5. In conclusion, the L4 fermentation process can significantly enrich the active ingredients in red sour soup.

[0036] Table 2. Total phenols, total flavonoids, and vitamin C content of L4 red sour soup at different fermentation times.

[0037] 3.3 Antibacterial activity in the L4 fermented red sour soup system (1) Sample pretreatment Take 10 g (or 10 mL) of homogeneous L4 fermented red sour soup sample and place it in a 250 mL Erlenmeyer flask containing 90 mL of sterile physiological saline (0.85% NaCl) and several sterile glass beads. Vortex thoroughly for 20 min, or until the sample is completely homogenized, to prepare 10 g of the sample. -1 The initial sample homogenate.

[0038] (2) Gradient dilution In the biosafety cabinet, accurately pipette 1 mL of 10 mL of liquid. -1 The sample homogenate was injected into a test tube containing 9 mL of sterile physiological saline, and gently mixed by pipetting to prepare 10... -2Diluent. Following this method, prepare a series of 10-fold dilutions to 10... -7 (Usually 10 is selected) -4 Up to 10 -7 (Apply the coating in gradients). Replace the sterile pipette tip at each dilution.

[0039] (3) Lactic acid bacteria count Culture medium: Use MRS agar medium, autoclave at 121℃ for 15 min, and then cool to 45-50℃. Pour the liquid onto a flat plate for later use.

[0040] Inoculation and culture: Select 2-3 suitable dilutions, and inoculate 0.1 mL of bacterial suspension onto MRS plates using the spread plating method. Perform 3 replicates for each dilution. After the bacterial suspension has been absorbed, invert the plates into anaerobic incubators and incubate anaerobically at 37°C for 48-72 h.

[0041] Counting: Select plates with colony counts between 30 and 300 for counting. Lactic acid bacteria colonies are typically milky white, round, with regular edges and a smooth surface.

[0042] (4) Total count of fungi (yeast and mold) Culture medium: Potato glucose agar (PDA) was autoclaved at 121°C for 15 min. When cooled to about 50°C, chloramphenicol solution (final concentration 50 μg / mL) was added after filtration and sterilization. After mixing, the mixture was poured into plates.

[0043] Inoculation and culture: Select 2-3 suitable dilutions, and spread 0.1 mL of bacterial culture onto PDA plates for each dilution. Perform 3 replicates for each dilution. Incubate the plates upside down in a 28℃ incubator for 3-5 days.

[0044] Counting: Count yeast colonies (usually moist, viscous, and milky white) and mold colonies (fluffy, flocculent, or powdery, often producing pigment), or report the total fungal count. Select plates with colony counts between 10 and 150 for counting.

[0045] Monitoring the trend of microbial community changes during the fermentation process showed that ( Figure 4 In the L4 fermentation group, due to the rapid start-up and nutrient consumption in the early stage of fermentation, the number of lactic acid bacteria increased from 9.3 × 10⁻⁶ on day 1. 7 CFU / mL gradually decreased to 2.48 × 10⁻⁶ on day 22. 4 The trend of CFU / mL. In terms of inhibiting putrefactive bacteria, the L4 fermentation group showed significant antifungal ability. During the first 17 days of fermentation, the fungal colony count in the L4 group remained below 1.0 × 10⁻⁶. 1 CFU / mL decreased to only 3.14 × 10⁻⁶ on day 22. 3CFU / mL. No deterioration characteristics were observed in the L4 fermentation group throughout the entire cycle. Figure 5 The results showed that inoculation with L4 fermentation could effectively inhibit the growth and reproduction of fungi and other miscellaneous bacteria, significantly prevent the formation of mold and flowers in the fermentation system, and demonstrated excellent fermentation stability and anti-fouling ability.

[0046] Comparative Experiment 1: Inhibitory Effects of Other Lactobacilli on Putrefactive Bacteria Other lactobacilli (L2, L3, L6, L8, L21, L23, RY, RF-1, RF-2, RF-6) were used instead of strain L4 in Example 1, with the remaining experimental procedures unchanged. RY was *Lactobacillus paracasei*, L2 was *Lactobacillus fructose*, L3 was *Lactobacillus double fermentation*, L6 was *Lactobacillus fructose*, and the rest were *Lactobacillus plantarum*. The antibacterial effects of different lactobacilli against yeast are shown in the table. Based on the combined results of the double-layer plate test and the Oxford cup inhibition zone test, L4 showed the best antibacterial effect against *Prunella vulgaris*.

[0047] Table 3. Diameter of the inhibition zone of Lactobacillus (mm)

[0048] Note: The diameter of the Oxford cup hole is 8.0 mm. Comparative Experiment 2: Physicochemical Quality of Fermented Red Sour Soup Without L4 Bacterial Solution The ingredients from Example 3 were naturally fermented without inoculation with L4 bacterial culture, while all other conditions remained unchanged. The results showed that the total acid content in the CK group increased sharply after 4 days, remaining at a high level of approximately 11.3 g / kg from 10 to 14 days. Correspondingly, the pH value gradually decreased from 4.22 on day 1, reaching a low of 3.40-3.47 on days 4-5, and then stabilizing in the acidic range of 3.45-3.57. Regarding amino acid nitrogen, the CK group showed relatively small fluctuations, with a peak of only 8.703 mg / 100g on day 1. The soluble solids content remained high at 9.767%-10.467% from day 2 to 7 (reaching a peak of 10.467% on day 7), subsequently decreasing to 8.200% on day 14. The reducing sugar content remained high at 0.811-0.863 mg / g from day 1 to day 3, and was rapidly consumed after day 4, decreasing to 0.277 mg / g and 0.261 mg / g at the end of fermentation on day 10 and day 14, respectively.

[0049] Table 4 Physicochemical properties of fermented red sour soup (control group, CK)

[0050] Figure 6The results showed that the total phenol content in the naturally fermented group was 2.822 mg GAE / g; the total flavonoid content was 7.846 mg / 100 g; and the vitamin C content was only 7.868 mg / 100 g. In summary, the use of L4 fermentation agent can significantly improve the enrichment levels of active ingredients such as total phenols, total flavonoids, and vitamin C in red sour soup, demonstrating good technical effectiveness.

[0051] Figure 4 The results showed that after natural fermentation began, the number of lactic acid bacteria first increased and then decreased, reaching a peak of 5.8 × 10⁸ on day 5. 6 CFU / mL eventually decreased to 6.3 × 10⁻⁶. 3 CFU / mL; Regarding fungal control, the natural fermentation group achieved a fungal count of 3.2 × 10⁻⁶ on day 10. 2 CFU / mL, then continued to rise, reaching 1.88 × 10⁻⁶ on day 17. 6 CFU / mL. Meanwhile, the naturally fermented group began to show obvious membrane formation on day 14. Figure 7 In contrast, no film formation was observed in the L4 fermentation group throughout the entire fermentation process, indicating that inoculation with L4 starter culture can effectively inhibit the growth and reproduction of fungi and other miscellaneous bacteria, significantly prevent the formation of film in the fermentation system, and demonstrate good fermentation stability and anti-film and anti-pollution capabilities.

[0052] Finally, it should be noted that the above embodiments are merely representative examples of this application. Obviously, the technical solutions of this application are not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the content disclosed in this application should be considered within the scope of protection of this application.

Claims

1. A strain of lactobacillus that inhibits biofilm formation, characterized in that, It is deposited at the China Center for Type Culture Collection, with accession number CCTCC M2026240, and the deposit date is January 26, 2026.

2. The lactobacillus that inhibits biofilm formation according to claim 1, characterized in that, The lactobacillus that inhibits biofilm formation is *Lactobacillus brevis* (…). Lentilactobacillus buchneri ).

3. The lactobacillus that inhibits biofilm formation according to claim 1, characterized in that, The biofilm-inhibiting lactobacillus has rod-shaped cells, is Gram-positive, and negative for catalase test.

4. The application of the biofilm-inhibiting lactobacillus as described in claim 1 in the fermentation of sour soup.

5. The application according to claim 4, characterized in that, The application described in the fermentation of sour soup is to inhibit harmful mold and yeast contamination during the fermentation process.

6. The application according to claim 5, characterized in that, The harmful yeast contamination refers to harmful yeasts that produce biofilms.

7. The application according to claim 6, characterized in that, The harmful yeast that produces biofilm is Pichia pastoris, a biofilm-producing yeast.

8. The application according to claim 4, characterized in that, The sour soup mentioned is Guizhou fermented sour soup.

9. The application according to claim 8, characterized in that, The Guizhou fermented sour soup is made by fermenting chili peppers, tomatoes, ginger, and garlic as the main ingredients.

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