Screening and lactate-producing ability evaluation of acetic acid-tolerant lactic acid bacteria

Abstract:

[Background] Acetic acid-tolerant lactic acid bacteria are important for lactic acid and its derivatives production during acetic acid fermentation in traditional cereal vinegar brewing process. [Objective] To screen acetic acid-tolerant lactic acid bacteria from vinegar Pei of Zhenjiang aromatic vinegar, and evaluate its fermentation performance. [Methods] Selective MRS medium containing 4% (volume ratio) acetic acid was used to isolate acetic acid-tolerant lactic acid bacteria. The isolated strain was identified by 16S rRNA gene sequencing, whole genome sequencing and morphological, physiological and biochemical analyses. Lactic acid-producing ability of the isolated stain was evaluated under different culture conditions. [Results] A lactic acid bacterial strain JN500903 that resisted 6% acetic acid was screened and identified as Lactobacillus sp. The optimum conditions for lactic acid production were: anaerobic static culture, inoculum of 5%, acetic acid concentration of 5%, glucose concentration of 40 g/L, fermentation temperature at 37 °C and fermentation period of 10 d, the lactic acid production was 16.1 g/L under these conditions. [Conclusion] Strain JN500903 can produce lactic acid under the 6% acetic acid stress, suggesting its potential for industrial application.

Key words:Acetic acid-tolerant, Lactic acid bacteria, Vinegar Pei, Zhenjiang aromatic vinegar