Metabolic characteristics of lactic acid bacteria and interaction with yeast isolated from light-flavor Baijiu fermentation

During spontaneous fermentation of light-flavor Baijiu, the microbial diversity decreased gradually. Lactic acid bacteria (LAB) and yeast predominated at the end of fermentation and showed a strong positive correlation with esters in Baijiu. Exploring the metabolic characteristics of LAB and interactions with yeast are important for revealing the mechanism of Baijiu fermentation. The carbon source utilization heatmap showed that Lactobacillus acetotolerans, Lactobacillus brevis, and Lactobacillus hilgardii could utilize various organic acids. Lactobacillus plantarum could utilize a variety of amino acids. The utilization efficiency of different substrates was supposed to be an important factor for different LAB species dynamics during fermentation. The effects of pH, temperature and ethanol on the esterase activity of LAB were further analyzed. The results showed that pH was the most significant factor on esterase activity, and all the strains showed the highest activity at pH 7.0. Principal component analysis indicated that co-culture of LAB and Saccharomyces cerevisiae could promote the formation of esters, and the co-culture of Lactobacillus acetotolerans or Leuconostoc mesenteroides with Pichia anomala could promote the production of esters and alcohols. LAB showed a weak inhibitory effect on the growth of yeast, whereas the growth of LAB was significantly inhibited by yeast in the co-culture system. The results of this work will broaden our knowledge regarding the esterase activity, carbon source utilization efficiency of LAB and interactions with predominant yeast, which will provide a theoretical basis for the dynamics of different LAB species and their effects on the flavor of Baijiu.