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.
