云南傣族地区酸菜中发酵乳酸菌的筛选及鉴定

Screening and Identification of Strains of Lactic Acid Bacteria for Fermentation from Suancai in the Dai Ethnic Region of Yunnan

摘要:

【目的】筛选适用于酸菜发酵的乳酸菌。【方法】以云南傣族地区传统发酵酸菜为研究对象，分离纯化乳酸菌，并对其发酵性能（亚硝酸盐降解力、产酸能力、耐酸性、耐盐生长能力）、抑菌性、药物敏感性、溶血性和氨基酸脱羧酶活性等特性进行研究，以确定优势菌株。【结果】从40份酸菜样本中共分离出208株乳酸菌。通过亚硝酸盐降解能力的初步筛选，获得20株高效菌株，其中15株经16S rDNA分子鉴定为植物乳植杆菌，2株为短乳杆菌，1株为发酵乳杆菌，1株为食窦魏斯氏菌，1株为戊糖乳杆菌。经亚硝酸盐复筛试验，有5株菌降解率在95%以上，4株菌产乳酸质量浓度高达21 g/L。其中菌株D8的亚硝酸盐降解率为（98.42±0.45）%，发酵24 h后，pH下降至3.63±0.05，产酸量高达（22.65±0.05） g/L；在质量分数为8%的NaCl溶液中，其OD₆₀₀值达2.002±0.012；在pH=3的溶液中，其OD₆₀₀值为0.268±0.038，表现出了良好的耐酸、耐盐生长特性。菌株D8对大肠埃希氏菌、金黄色葡萄球菌、鼠伤寒沙门菌的抑菌圈直径分别为（18.40±0.08）、（19.36±0.24）、（16.52±0.57） mm，抑菌效果优越。所有菌株均无溶血活性，且精氨酸、赖氨酸、鸟氨酸脱羧酶活性试验结果均为阴性，对大部分抗生素敏感。【结论】菌株D8是适用于酸菜发酵的优势菌株。

Abstract:

[Objective]This study aims to screen the strains of lactic acid bacteria (LAB) suitable for Suancai fermentation.[Method]Traditional fermented Suancai from the Dai ethnic region of Yunnan was used as the research samples for the isolation and purification of LAB. The purified isolates were evaluated for fermentation characteristics, including nitrite degradation, acid production, acid resistance, and salt tolerance. Additionally, the antimicrobial activity, antibiotic susceptibility, hemolytic activity, and amino acid decarboxylase activity were assessed to identify dominant strains.[Result]A total of 208 LAB strains were isolated from 40 Suancai samples. Preliminary screening based on nitrite degradation identified 20 strains with high efficiency, and 16S rDNA sequencing identified 15 strains of Lactobacillus plantarum, 2 strains of Levilactobacillus brevis, 1 strain of Limosilactobacillus fermentum, 1 strain of Weissella cibaria, and 1 strain of Lactiplantibacillus pentosus. The secondary screening based on nitrite degradation revealed 5 strains with nitrite degradation efficiencies >95%, as well as 4 strains producing lactic acid at mass concentrations higher than 21 g/L. Among them, strain D8 demonstrated the nitrite degradation rate reaching (98.42±0.45)%, decreasing the pH to 3.63±0.05 and producing lactic acid as high as (22.65±0.05) g/L after 24 h of fermentation. Additionally, the OD₆₀₀ value of the strain reached 2.002±0.012 in a NaCl solution with the mass fraction of 8% and 0.268±0.038 in a solution with pH 3, indicating excellent acid and salt tolerance. Strain D8 showed the inhibition zone diameters of (18.40±0.08) mm against Escherichia coli, (19.36±0.24) mm against Staphylococcus aureus, and (16.52±0.57) mm against Salmonella typhimurium, indicating remarkable antimicrobial performance. All the strains were non-hemolytic and tested negative for arginine, lysine, and ornithine decarboxylase, and susceptible to most antibiotics.[Conclusion]Comprehensive evaluation suggests strain D8 as the dominant strain for Suancai fermentation.