乳酸菌的乙醇耐受机制及其在食醋生产中的应用OACSTPCD

Traditional solid-state fermented vinegar has superior flavor and quality due to its rich flora.As lactic acid bacteria are important functional microorganisms in solid-state vinegar fermentation,they are widely used in food-related and biological fields.However,lactic acid bacteria are stressed by high ethanol concentrations during vinegar fermentation.Therefore,how lactic acid bacteria survive at high ethanol concentrations should be explored.In this study,ethanol-tolerant Lactobacillus paracasei PC-5 and ethanol-intolerant Lactobacillus plantarum PR-7 were selected for comparison.Based on the biological indicators,the polysaccharide content and cell membrane permeability of PC-5 increased to 0.56%and 75%,respectively,and were significantly higher than those of PR-7 in an ethanol environment with a volume fraction of 8%.PC-5 outperformed PR-7 in terms of the activities of hexokinase(HK),6-phosphofructokinase(PFK),and pyruvate kinase(PK)in the metabolic pathway,with activities increasing to 99.80,2.78,and 3.43 U/mg,respectively.Finally,PC-5 was added to the vinegar at different fermentation stages to achieve mixed culture co-fermentation with yeast.Polyphenol production and total antioxidant capacity were found to increase by 32.14%and 55.56%,respectively,compared with those of single culture bacteria fermentation.Therefore,lactic acid bacteria had positive stimulation effects on vinegar fermentation.Such findings provide a good theoretical basis for the use of lactic acid bacteria in mixed culture fermentation of vinegar.