Isolation and Screening of Salt-Tolerance Lactic Acid Bacteria Strains from Soy Sauce Mash and Study on Its Characteristic Producing Lactic Acid

Abstract:

The salt-tolerance lactic acid bacteria strain was isolationed and identified from soy sauce mash in this study. The ability producing lactic acid was studied in different culture conditions. The salt-tolerance lactic acid bacteria strain was isolationed and screened by MRS medium with CaCO3 and NaCl gradient plate from soy sauce mash. They were identified according to morphorlogy characters and 16S ribosomal RNA(rRNA) gene sequencing methods. The ability producing lactic acid was studied at different fermentation temperature, NaCl concentration and pH value. The results showed: the strain with superior salt-tolerant was identified as Lactobacillus delbrueckii subsp. bulgaricus. The optimum temperature was 38 ℃. When NaCl concentration was 18%, the titer of lactic acid reach at 22.68 g/L. furthermore, it was found that a a high lactic acid production was achieved at a neutral or slight alkaline environmental .