Separation screening and application of lead adsorption fermentation lactobacillus mucilaginosus

Abstract

The invention discloses separation, screening and application of lead adsorption fermentation lactobacillus mucilaginosus, and belongs to the field of lead adsorption based on a microbial technology. The lactobacillus plantarum RS7 disclosed by the invention has good acid production and acid resistance, and the adsorption rate to lead in a lead-containing MRS liquid culture medium is the highest and reaches 95%. Meanwhile, the preserved egg has good endurance capacity and adsorption capacity to lead ions in vitro, the content of lead in the preserved egg can be reduced, and the lead removal rate reaches about 60% after 48 h. The lactobacillus mucus RS7 is used for fermented food with a lead discharging function and other environments such as sewage polluted by lead, and has a very wide application prospect.

Description

Technical Field

[0001] The invention relates to the separation, screening and application of a lead adsorption and fermentation mucus lactobacillus, and belongs to the field of lead adsorption based on microbial technology. Background Art

[0002] Lead pollution in food mainly comes from human pollution. As a heavy metal, lead is highly toxic and permeable, and its natural degradation rate is very low, making it difficult to treat harmlessly. In the process of food processing, some traditional processing methods or equipment used may introduce lead pollution. For example, in the traditional production of preserved eggs, lead oxide is usually used as a food additive to make it better shaped. Some traditional popcorn machine furnace covers and furnaces are cast from lead-containing pig iron, which easily volatilizes and enters the popcorn when heated in a closed environment. At the same time, some food containers and packaging materials, such as food cans made of lead solder, lead-containing plastic packaging, and lead-containing food additives, may cause food to be contaminated with lead and endanger human health.

[0003] At present, there are physical, chemical and biological methods for the removal of lead. In recent years, microbial adsorption has been widely used in the treatment of heavy metal wastewater and soil due to its advantages of ease of use, high removal efficiency, abundant resources, low cost and few by-products. Bacteria are the most abundant microorganisms on the earth. Studies have shown that many types of bacteria, such as Lactobacillus, Pseudomonas, Bacillus subtilis, Enterobacter reuteri and other bacteria and their products have strong binding ability with metal ions. The phosphate polysaccharide in the cell wall of Gram-positive bacteria and the lipopolysaccharide in the outer layer of the peptidoglycan of the cell wall of Gram-negative bacteria are both strongly negatively charged. This charge characteristic enables them to adsorb heavy metal ions, and because there is a high affinity between the structural components of the bacterial outer membrane and metal ions, metal ions are easily adsorbed by bacteria. This adsorption not only reflects the chemical characteristics of the bacterial cell wall components, but also reveals the potential treatment ability of bacteria for heavy metal pollutants in the environment.

[0004] Lactic acid bacteria (LAB) are non-pathogenic, safe Gram-positive bacteria that can ferment carbohydrates and produce a large amount of lactic acid. Lactic acid bacteria participate in many metabolic activities in the human body, improve intestinal microbial flora and intestinal function, reduce serum cholesterol levels, enhance the body's immune function, prevent and inhibit tumor metabolism, improve food metabolism, facilitate digestion and absorption, improve vitamin metabolism and delay body aging, and also have the effect of improving food flavor. In recent years, heavy metal pollution in food has attracted more and more attention. In addition to its special health care ability for the human body, lactic acid bacteria also have the ability to adsorb heavy metals. Compared with traditional heavy metal removal methods, the removal effect of lactic acid bacteria has attracted more attention. Therefore, more and more researchers have joined the research on the adsorption of heavy metals by lactic acid bacteria. Man Zhaohong et al. screened out lead-resistant bacteria from the intestinal contents and excrement of broilers for the removal of heavy metal lead, among which the JT1 strain had the highest lead removal capacity of 66.95%; Bifidobacterium longum, Lactobacillus fermentum and Bifidobacterium lactis isolated by Halttumen et al. can effectively remove heavy metal lead, among which Bifidobacterium longum can remove lead by 175.7 mg / g; Ma Hongmei et al. analyzed the effects of three different lactic acid bacteria, Lactobacillus delbrueckii, Streptococcus thermophilus and Enterococcus faecium, on the adsorption of lead ions in seawater. These research reports show that lactic acid bacteria that can adsorb heavy metals have the potential to remove heavy metals from the human body, thereby reducing the damage of heavy metals to the human body. However, the lactic acid bacteria currently reported have poor lead adsorption and low survival rate in a high-concentration lead environment, and the types of lead salts adsorbed are limited. More excellent lactic acid bacteria are needed to improve this situation. Therefore, it is necessary to screen out a lactic acid bacteria with excellent tolerance and adsorption capacity to high concentrations of lead, and to prove that they have good lead-excretion effects in different forms of lead-containing fermented foods, while also developing the practical uses of these lactic acid bacteria. Summary of the invention

[0005] The purpose of the present invention is to provide a strain that can survive in a high-concentration lead environment and has a strong adsorption effect on various forms of lead.

[0006] [Technical solution]

[0007] The present invention is achieved through the following technical solutions.

[0008] The present invention relates to a lactic acid bacterium, which is identified as Limosilactobacillus fermentum RS7 by microbiological characteristics such as morphological characteristics, culture characteristics, and physiological and biochemical characteristics. The strain has been deposited in the Guangdong Provincial Microbiological Culture Collection Center on August 15, 2024, with a deposit number of GDMCC No: 64983. The address of the preservation unit is the Institute of Microbiology, Guangdong Academy of Sciences, 5th Floor, Building 59, Compound 100, Xianlie Middle Road, Guangzhou. The fermented mucus lactobacillus RS7 can be used to remove lead elements in matrices such as feed, soil, culture medium, etc., and can tolerate a lead concentration of up to 250 mg / L. Under the condition of pH 6, the lead adsorption rate of 100 mg / L lead acetate solution is more than 50%, and the removal rate of lead acetate in 100 mg / L solution reaches 74.17%.

[0009] In one embodiment, the fermented Lactobacillus mucilaginosus RS7 of the present invention has the following properties:

[0010] (1) It is acid-resistant and grows well in an environment with a pH of 3.0-8.0 and survives well in an environment with a pH of 2.5;

[0011] (2) Cultivated in lead-containing culture medium in vitro, the cells have good tolerance to lead ions;

[0012] (3) When incubated in an aqueous lead solution in vitro, it has a good adsorption capacity for lead ions;

[0013] (4) It has the potential to reduce the lead content in lead-containing fermented foods and promote lead excretion from lead-containing fermented foods mainly through lead adsorption.

[0014] In one embodiment, in some embodiments of the present invention, the base sequence of the 16SrRNA gene of the fermentative Lactobacillus mucilaginosus RS7 is as shown in SEQ ID NO.1.

[0015] In one embodiment, the fermentation Lactobacillus mucilaginosus RS7 has a bile salt tolerance concentration of 0.3%.

[0016] In one embodiment, the fermented Lactobacillus mucilaginosus RS7 has good acid resistance, and the fermented Lactobacillus mucilaginosus RS7 can basically grow normally between pH 3-7.

[0017] In one embodiment, the fermented Lactobacillus mucilaginosus RS7 has a good acid production capacity, and the acid production can be reduced from the initial 6.31 to 4.1 after 12 hours of fermentation.

[0018] In one embodiment, the fermented mucus Lactobacillus RS7 has a good lead tolerance, and in a solution with a lead ion concentration of 100 mg / L, the lactic acid bacteria still has a survival rate of more than 50%.

[0019] In one embodiment, fermented mucus Lactobacillus RS7 has good lead adsorption capacity and can be used to remove lead metal elements in a matrix, and the matrix can be lead-containing fermented food, soil, feed, culture medium and other substances from which lead needs to be removed.

[0020] The invention also provides a microbial preparation containing the fermented mucus lactobacillus RS7.

[0021] In one embodiment, the viable count of Lactobacillus mucilaginosus RS7 in the microbial preparation is not less than 1×10 9 CFU / mL or 1×10 9 CFU / g.

[0022] The invention also provides a product containing the fermented mucus lactobacillus RS7 or the microbial preparation.

[0023] In one embodiment, the product includes food, medicine, and health care products.

[0024] In one embodiment, the product comprises a food additive; preferably, the product comprises a heavy metal adsorbent.

[0025] In one embodiment, the product comprises a lead sorbent.

[0026] The present invention also provides a method for adsorbing lead, which comprises adding the fermented mucus lactobacillus RS7 or the microbial preparation into a matrix containing lead for culturing.

[0027] In one embodiment, the lead-containing matrix comprises a solid matrix, a liquid matrix, or a semisolid matrix.

[0028] In one embodiment, the type of lead includes lead acetate, lead oxide or lead nitrate.

[0029] In one embodiment, the adsorption conditions are: pH 3-7, and the adsorption time is at least 24 hours.

[0030] The present invention also provides the use of the fermented mucus lactobacillus RS7 or the microbial preparation in removing lead from a matrix, wherein the matrix includes food, soil, feed, and culture medium.

[0031] Furthermore, in some embodiments of the present invention, the pH of the matrix is ​​controlled to be 3-7.

[0032] Furthermore, in some embodiments of the present invention, the pH of the matrix is ​​controlled to be 5.5-6.3.

[0033] The present invention has found that under the condition of pH 3-7, the fermented Lactobacillus mucoides RS7 has a good lead adsorption rate. For example, under the condition of pH 6, its lead adsorption rate exceeds 70%, indicating that the fermented Lactobacillus mucoides RS7 has good application potential.

[0034] The present invention also provides the use of the fermented mucus lactobacillus RS7 or the microbial preparation in preparing a lead adsorbent.

[0035] Beneficial effects:

[0036] The invention provides a fermented mucus lactobacillus RS7. The fermented mucus lactobacillus RS7 has good acid resistance, bile salt resistance and lead resistance, can adsorb lead ions in lead acetate, lead nitrate and lead oxide solutions, and has a lead removal rate of 74.17% in a solution with a lead ion concentration of 100 mg / L; and has a lead removal rate of 95% in a solution with a lead ion concentration of 50 mg / L.

[0037] The application of this strain has a good lead adsorption effect on fermented foods containing lead and water bodies contaminated by lead in soil. Finally, fermented mucus lactobacillus RS7 can be prepared into a highly active microbial preparation, which is convenient for application in lead-contaminated matrices, and can also be used as a lead adsorbent, alone or in combination with an adsorbent with similar functions, to reduce the lead content in food and the environment.

[0038] Biomaterial Deposit

[0039] A strain of Lactobacillus fermentum RS7, taxonomically named Limosilactobacillus fermentum, was deposited in Guangdong Microbiological Culture Collection Center on August 15, 2024, with the deposit number GDMCC No: 64983. The address of the deposit unit is the Institute of Microbiology, Guangdong Academy of Sciences, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a picture of lactic acid bacteria separation on a plate.

[0041] Figure 2 Gram staining results of lactic acid bacteria.

[0042] Figure 3 Degradation rate of lead by different strains.

[0043] Figure 4Screening of strains for acid resistance.

[0044] Figure 5 Phylogenetic tree of lactic acid bacteria RS7 based on 16S rDNA gene.

[0045] Figure 6 Scanning electron micrographs of the strain before (left) and after (right) lead adsorption.

[0046] Figure 7 Removal rate of lead in preserved eggs by strain RS7. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0048] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0049] The adsorption rate of lead ions by the strains involved in the following examples was calculated according to the following formula:

[0050] Adsorption rate (%) = [(A0-A1) / A0] × 100%;

[0051] Wherein A0 represents the lead ion concentration of the initial solution, A1 represents the lead ion concentration of the solution after adsorption, and the lead ion concentration is detected by a flame atomic absorption spectrophotometer.

[0052] Example 1 Screening and identification of fermented mucus Lactobacillus RS7

[0053] 1. Isolation and screening of lead-adsorbing lactic acid bacteria

[0054] Take 1 mL of fermented food slurry such as kimchi, yogurt, and Yakult and add it to 30 mL of MRS liquid medium. Incubate it in a shaker at 37°C and 120 r / min for 48 hours to enrich lactic acid bacteria. Streak the liquid medium after 48 hours of enrichment onto MRS solid medium, place it in a biochemical incubator and invert it at 37°C for 48 hours, and take a single colony for separation and purification 3 times ( Figure 1 ), and subject the obtained strain to catalase test and Gram staining microscopy to preliminarily determine whether it is lactic acid bacteria.

[0055] The target strain obtained from the initial screening of the plate was picked out of a single colony and placed in 30 mL of MRS liquid culture medium. After constant temperature shaking and culture at 37 ° C and 120 r / min in a shaking incubator for 48 h, the inoculation amount was 1% (the initial inoculation amount was 10 6CFU / ml) was inoculated into 30mL of MRS liquid culture medium containing 100mg / L lead acetate and cultured in an oscillating incubator for 48h. An MRS liquid culture medium containing an equal amount of lead but no inoculation was used as a control. The culture solution was then centrifuged at 8000r / min for 20 minutes in a high-speed refrigerated centrifuge. After centrifugation three times, the lead content in the supernatant was determined using flame atomic absorption spectrometry. The degradation rate of lead by the test strain was calculated based on the lead content in the initial MRS liquid culture medium. The results showed that different strains had different adsorption rates for lead, among which the RS7 strain had the highest adsorption rate for lead of 74.17% ( Figure 3 ), so we identified this strain.

[0056] 2. Identification of lactic acid bacteria

[0057] (1) Gram staining

[0058] Pick a single lactic acid bacteria colony and mix it in 10 μL of sterile aqueous solution, spread it on a sterile slide, quickly fix it on a flame, cool it down, follow the Gram staining steps, observe it under an inverted microscope with an oil immersion lens, and confirm it as a Gram-positive bacterium ( Figure 2 ).

[0059] (2) 16S r RNA biological identification

[0060] After the screened lead-resistant strains were cultured overnight, the bacterial solution was taken to extract the genomic DNA of lactic acid bacteria according to the instructions of the DNA extraction kit, and the extracted DNA was used as a template for polymerase chain reaction amplification with universal primers, wherein the forward primer was 27F (5'-TGAGAGTTTGATCCTGGCTCAG-3') and the reverse primer was 1492R (5'-TACGGCTACCTTGTTACGAC-3'), which were synthesized by Shanghai Shenggong Biotechnology Co., Ltd. The PCR amplification system was 25 μL of 2X SanTaqPCR Mix (containing blue dye), 2 μL of DNA template, 2 μL of forward primer 27F, 2 μL of reverse primer 1492R, and Sterilized ddH2O was added to 50 μL, which was fully mixed and centrifuged briefly, and the reaction tube was placed in a PCR instrument for reaction. The PCR reaction conditions were 94°C pre-denaturation for 5 min, followed by PCR cycles, 94°C denaturation for 30 s, 55°C annealing for 30 s, 72°C extension for 90 s, a total of 35 cycles, and 72°C final extension for 10 min. After amplification, the PCR tube was placed in a 4°C refrigerator. A small amount of PCR amplification product was then taken for electrophoresis using 1% agarose gel to observe the amplification results, and the amplification product was sent for sequencing to Shanghai Bioengineering Company. After sequencing, the sequencing results were aligned by Blast on NCBI, and a gene phylogenetic tree was constructed using MEGA11.0 using the Neighbour-Joining method.

[0061] The 16S rRNA gene sequencing results are as follows (SEQ ID NO.1):

[0062]

[0063] The phylogenetic tree constructed based on 16S rRNA gene sequences is shown in Figure 5 ,according to Figure 5 As a result, it can be seen that RS7 is a fermented mucus Lactobacillus, and the fermented mucus Lactobacillus RS7 has been deposited in the Guangdong Provincial Microbiological Culture Collection Center on August 15, 2024, with the preservation number GDMCC NO: 64983.

[0064] Example 2 Characterization of the properties of fermented Lactobacillus mucilaginosus RS7

[0065] (1) Acid resistance of fermented Lactobacillus mucilaginosus RS7

[0066] The acid resistance of RS7 with higher lead adsorption capacity obtained by repeated screening was tested. The results are as follows Figure 4 As shown in the figure, it can be seen that RS7 can basically grow normally between pH 4-7. When the pH value is less than 3, both strains can hardly grow normally, so lactic acid bacteria cannot grow normally in a low acid environment (pH < 3).

[0067] The enhanced tolerance of lactic acid bacteria may be achieved by generating ammonia and arginine metabolism to maintain a suitable pH value in the cell. Arginine decarboxylase and urease pathways are two common pathways for generating NH3 in Gram-positive bacteria. + When lactic acid bacteria are in a low-acid environment, they mainly produce ammonia through the arginine decarboxylase pathway (Arginine decarboxylase, A-DI), thereby increasing the acidity in the cells and maintaining the pH balance in the cells.

[0068] (2) Bile salt tolerance of fermentative Lactobacillus mucilaginosus RS7

[0069] Table 1 Bile salt tolerance of screened strains

[0070]

[0071] The RS7 with higher lead adsorption capacity obtained by repeated screening was tested for its bile salt tolerance, as shown in Table 1. The time required for strain RS7 to grow in MRS was 1.13 h, and the time required for growth in MRS with 0.3% bile salt was 1.67 h, which was 0.54 h slower than the growth in MRS, indicating that RS7 had a certain tolerance to bile salts.

[0072] (3) Maximum lead tolerance of Lactobacillus mucilaginosus RS7

[0073] The fermented mucus Lactobacillus RS7 obtained in Example 1 was inoculated into 20 mL of MRS liquid culture medium at a 1% inoculum amount and cultured for 18 h. The absorbance was adjusted to 1 (OD 600), and then inoculated into MRS liquid culture medium containing final lead acetate concentration of 10 mg / L, 20 mg / L, 40 mg / L, 60 mg / L, 80 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, and 250 mg / L respectively according to the inoculum amount of 1% (v / v), and cultured at 37°C for 72 h to observe the results, and determine the maximum lead concentration that fermented mucus lactobacillus RS7 can tolerate. When the lead concentration exceeds 250 mg / L (Table 2), the survival rate of fermented mucus lactobacillus RS7 is 0; in the lead concentration range of 10-100 mg / mL, the survival rate of fermented mucus lactobacillus RS7 is above 46%.

[0074] Table 2 Survival rate of fermented Lactobacillus mucilaginosus RS7 under different lead concentrations

[0075]

[0076] (4) Adsorption of lead ions by fermented Lactobacillus mucilaginosus RS7

[0077] The lactic acid bacteria screened in Example 1 were inoculated into MRS liquid culture medium and cultured at 37°C for 24 h. Then, the inoculum was inoculated into MRS liquid culture medium containing 100 mg / ml lead acetate (initial inoculation concentration was 10 6 CFU / mL), and cultured in a shaker at 37°C for 48 hours. The lactic acid bacteria fermentation broth cultured for 48 hours was centrifuged at 8000 rpm for 20 minutes, and the centrifugation was repeated three times. The supernatant was taken to measure the lead ion concentration in a flame atomic absorption spectrophotometer, and the precipitate was collected for subsequent electron microscopy detection.

[0078] The results showed that the lead adsorption rate of fermented Lactobacillus mucilaginosus RS7 on 100 mg / L lead acetate solution was 74.17% ( Figure 3 ). This adsorption effect is much higher than the adsorption effect of Lactobacillus rhamnosus IBRC-M 10782 reported in the literature. In addition, we further increased the concentration of lead acetate solution to 150 mg / L and measured the adsorption rate of fermented mucus lactobacillus RS7. The results showed that the adsorption rate could still reach 42% at this concentration, which was also higher than the adsorption rate of lead by fermented Lactobacillus HNU312 at 150 mg / L (27.8%), indicating the advantage of fermented mucus lactobacillus RS7 in lead adsorption.

[0079] Further, the adsorption effect of fermented mucus lactobacillus RS7 under different conditions was investigated, and then we reduced the lead acetate concentration to 50 mg / L and investigated its lead adsorption rate after 24 hours and 48 hours. The results showed that the adsorption rate of lead by fermented mucus lactobacillus RS7 reached 89% after 24 hours, and the adsorption rate of lead by fermented mucus lactobacillus RS7 reached 95% after 48 hours, indicating that the adsorption effect of lead by fermented mucus lactobacillus RS7 was better when the lead concentration was reduced.

[0080] (5) Mechanism of lead degradation by fermentative Lactobacillus mucilaginosus RS7

[0081] Heavy metal Pb 2+ The treated (the collected cells after lead adsorption in step 4) and untreated cells were collected after centrifugation at 5000×g for 10 min, then immersed in 2.5% glutaraldehyde for fixation, and fixed in a 4°C refrigerator overnight. After fixation, the cells were rinsed 3 times with 0.1 mol / L PBS solution (pH 7.2), each time for 10 min, and then dehydrated with gradient ethanol (50%, 70%, 80%, 90%, 95%, 100%), each time for 15 min; the excess ethanol was replaced with isoamyl acetate, and then placed in a -80°C refrigerator for 24 h, and dried with a freeze dryer for scanning electron microscopy observation.

[0082] Figure 6 The following are scanning electron microscope images of the strain before and after lead adsorption. (a) is a scanning image before lead adsorption. It can be seen that the bacteria are rod-shaped, and the cells are in good growth state, the cell surface is complete and smooth, and the outline is clear. (b) is a scanning image after lead adsorption. It can be seen that the bacterial cells are wrinkled and deformed, some bacteria become slender, and some particles are adsorbed on the surface of the bacteria, which may be related to the toxicity of lead. Heavy metals will change the hydrophobicity and charge of the cell surface, and then change the structure of the cell. At the same time, when the strain is stressed by heavy metals, the cell will detoxify through ion exchange and surface deposition of particles, resulting in cell surface adsorption. Therefore, extracellular precipitation may be one of the important ways for tolerant strains to adsorb heavy metals.

[0083] Example 3 Application of lead-adsorbing lactic acid bacteria on lead-containing preserved eggs

[0084] Take lead-containing preserved eggs (containing lead oxide, 20 mg / kg) and remove their shells. Add the preserved eggs and MRS broth into a juicer at a ratio of 1:2 (m / v, g / mL). Start the juicer to obtain preserved egg juice. Centrifuge at 10000×g for 20 min and add the supernatant to a 50 mL conical flask. Sterilize at 121°C for 15 min to obtain preserved egg MRS mixed culture medium. Fermented Lactobacillus mucilaginosus RS7 was added at 10 6The inoculum of CFU / mL was inoculated into the preserved egg MRS mixed culture medium and cultured in a shaker at 37°C and 120 r / min. A total of 4 groups of lead removal rate comparison experiments were set up at 0h, 24h, 48h, and 72h.

[0085] The results are as follows Figure 7 As shown in the data, the removal rate of lead in preserved eggs by strain RS7 was 28.68% at 24 h, and reached 58.88% at 48 h, more than double the removal rate at 24 h, indicating that RS7 has a good removal ability for lead in preserved eggs. The removal rate of lead reached 63.51% at 72 h, which is almost the same as the removal rate at 48 h, indicating that the adsorption capacity of lead in preserved eggs by strain RS7 has reached its limit, and also indicating that the growth of the strain has reached a stable period.

[0086] Example 4 Application of lead-adsorbing lactic acid bacteria on lead-containing rice

[0087] Rice (lead acetate, lead nitrate, 10 mg / kg) was crushed into rice flour using a universal crusher, and the rice flour and MRS broth were mixed in a ratio of 1:2 and sterilized at 121°C for 15 min to obtain rice-MRS culture medium. 6 The inoculum of CFU / mL was inoculated in sterilized rice-MRS medium, and the rice-MRS medium without the target strain was used as a blank control. It was cultured at 37°C for 72h, and three groups were set up in parallel. Under a sterile environment, 1mL of fermentation liquid was taken at 0h, 24h, 48h, and 72h, and the lead concentration was determined using a flame atomic absorption spectrophotometer and the lead removal rate was calculated. The results showed that the removal rate of lead in rice by strain RS7 was 31% at 24h, and the removal rate of lead reached 45% at 48h, indicating that fermented mucus lactobacillus RS7 also has good lead adsorption for rice.

[0088] Example 5 Application of lead-adsorbing lactic acid bacteria in lead-containing sewage

[0089] The fermented Lactobacillus mucilaginosus RS7 was 10 6 The inoculum of CFU / mL was inoculated into sewage containing lead (lead nitrate, 10-30mg / L), and 1mL of liquid was taken at 0h, 24h, 48h, and 72h in a sterile environment. The lead concentration was determined using a flame atomic absorption spectrophotometer and the lead removal rate was calculated. The results showed that the removal rate of lead in sewage by strain RS7 was 40% at 24h, and the removal rate of lead in sewage reached 65% at 48h, indicating that fermented mucus lactobacillus RS7 also has a good adsorption capacity for lead in sewage.

[0090] Example 6 Application of lead-adsorbing lactic acid bacteria on lead-containing fish

[0091] The fish was crushed into fish paste (lead acetate, 2-4 mg / kg) using a crusher, and the fish paste was mixed with sterile water at a ratio of 1:2, sterilized at 121°C for 15 min, and fermented mucus Lactobacillus RS7 was added at 10 6 The inoculation amount of CFU / mL was inoculated into the sterilized surimi liquid, and the surimi liquid treated in the same way without the target strain was used as the blank control. It was cultured at 37°C for 72h, and three groups were set up in parallel. Under a sterile environment, 1mL of fermentation liquid was taken at 0h, 24h, 48h, and 72h, and the lead concentration was determined using a flame atomic absorption spectrophotometer and the lead removal rate was calculated. The results showed that the removal rate of lead in surimi by fermented mucus Lactobacillus RS7 was 40% at 24h, and the removal rate of lead reached 65% at 48h, indicating that fermented mucus Lactobacillus RS7 also has good lead adsorption for lead-contaminated fish.

[0092] Example 7 Application of lead-adsorbing lactic acid bacteria on lead-contaminated soil

[0093] The lead-contaminated soil (containing lead acetate and lead nitrate, with a total content of 10-30 mg / kg) was dissolved in sterile water at a certain ratio (1:10, m / v), and then supplemented with a certain amount of nutrients such as carbon source (10% w / w glucose) and nitrogen source (5% w / w peptone). 6 The inoculation amount of CFU / mL was inoculated into the lead-containing soil solution, and the lead-containing soil treated in the same manner without the target strain was used as a blank control. 1mL of liquid was taken at 0h, 24h, 48h, and 72h in a sterile environment, and the lead concentration was determined using a flame atomic absorption spectrophotometer and the lead removal rate was calculated. The results showed that the lead removal rate of fermented mucus lactobacillus RS7 was 35% at 24h, and the lead removal rate reached 55% at 48h, indicating that fermented mucus lactobacillus RS7 also has a good adsorption capacity for lead in the soil.

[0094] Example 8 Preparation of fermented Lactobacillus mucilaginosus RS7 microbial preparation

[0095] The preparation method of fermented mucus lactobacillus RS7 microbial preparation (liquid) comprises the following steps: taking the preserved RS7 strain and activating and culturing it on an MRS solid culture medium, culturing it at 37°C for 24-48 hours, inoculating it into an MRS culture medium triangular shake flask, culturing it at 37°C for 24-48 hours, and using it for seed tank inoculation; the seed tank is also inoculated with the bacterial liquid after sterilization of the MRS culture medium, and culturing it at 37°C for 72 hours; the final number of viable bacteria reaches 10 9 CFU / mL is enough.

[0096] The preparation method of fermented mucus lactobacillus RS7 microbial preparation (solid) comprises the following steps: taking the preserved RS7 strains and activating and culturing them on an MRS solid culture medium, culturing them at 37°C for 24-48 hours, inoculating them into an MRS culture medium triangular shake flask, culturing them at 37°C for 24-48 hours, and using them for seed tank inoculation; the seed tanks are also inoculated with the bacterial solution after sterilization of the MRS culture medium, culturing them at 37°C for 72 hours, centrifuging, removing the supernatant to obtain the bacterial cells, using skim milk (10%, m / v) as a protective agent, mixing them with the bacterial cells at a ratio of 1:1 (v / m), and then freeze-drying them for 48-72 hours, and the number of viable bacteria in the final solid microbial preparation is not less than 10 9 CFU / g.

[0097] Example 9 Preparation of lead adsorbent

[0098] The powder containing a certain amount of microbial preparation in Example 8 was mixed with a powder prepared from a fiber-containing matrix such as pineapple peel and sugarcane bagasse in a certain ratio (1:1), and then prebiotics (1% inulin, 1% sodium alginate, 1% chitosan) were added. After mixing, the mixture was stored at 4°C. The number of viable bacteria in the prepared microbial preparation was not less than 10 7 CFU / g or CFU / mL.

[0099] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A fermented mucus lactobacillus (Limosilactobacillus fermentum) RS7, which has been deposited in Guangdong Provincial Microbiological Culture Collection Center on August 15, 2024, with a deposit number of GDMCC NO: 64983.

2. A microbial preparation containing the fermented mucus lactobacillus RS7 according to claim 1.

3. The microbial preparation according to claim 2, characterized in that The number of fermented mucus lactobacillus RS7 in the microbial preparation is not less than 1×10 9 CFU / mL or 1×10 9 CFU / g.

4. A product containing the fermented mucilaginous Lactobacillus RS7 according to claim 1, or the microbial preparation according to claim 2 or 3.

5. The product according to claim 4, characterized in that The products include food, medicine or health products.

6. The product according to claim 4, characterized in that The product comprises a food additive; preferably, the product comprises a heavy metal adsorbent.

7. A method for adsorbing lead, characterized in that: The fermented mucus Lactobacillus RS7 according to claim 1 or the microbial preparation according to claim 2 or 3 is added to a lead-containing matrix for culturing, characterized in that the culturing is carried out at a pH of 3-7 for at least 24 hours.

8. The method according to claim 7, characterized in that The lead-containing matrix includes a solid matrix, a liquid matrix or a semi-solid matrix; the type of lead includes lead acetate, lead nitrate or lead oxide.

9. The use of the fermented mucilaginous Lactobacillus RS7 according to claim 1, or the microbial preparation according to claim 2 or 3 in removing lead from a matrix, characterized in that: The substrate includes food, soil, feed or culture medium.

10. Use of the fermented mucilaginous Lactobacillus RS7 according to claim 1 or the microbial preparation according to claim 2 or 3 in the preparation of a lead adsorbent.

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