Safety assessment of Enterococcus lactis B3 isolated from the traditional Chinese fermented food Bianba and its effect on the quality change in radish paocai

Abstract

This study aimed to assess the safety and application of Enterococcus lactis B3, an unrecorded bacterium isolated from the traditional Chinese fermented food Bianba, in radish paocai. The whole genome sequencing verified the species level of strain B3 as E. lactis and detected antibiotic resistance and virulence genes, which are chromosomally located, suggesting a low risk of horizontal gene transfer. Additionally, the lack of plasmids reduces the risk of spreading resistance genes, and B3 was considered safe according to tests for antibiotic resistance, hemolysis, and gelatinase production. The strain B3 exhibited relatively strong artificial gastric juice (53.68 % ± 2.70 %) and bile salt (47.87 % ± 7.52 %) tolerances, which further revealed its probiotic potential. Thereafter, B3 was used as a starter to study its impact on paocai fermentation. The results suggested that inoculated fermentation led to a notably lower nitrite peak, more significant alterations in pH and titratable acidity in the initial stage of fermentation, stronger antioxidant capacity, higher levels of lightness, redness, and fracturability, and improved sensory parameters (appearance and texture) of the radish paocai samples compared with natural fermentation. Based on these findings, the strain B3 demonstrates safety characteristics and shows promising potential as a starter for fermented vegetables.