Changes in microbial communities and their predictive functionalities during fermentation of toddy, an alcoholic beverage of India

Abstract

Toddy is a traditional mild-alcoholic drink of India, which is produced from fresh palm saps by natural fermentation. We studied the successional changes in bacterial and fungal communities during the natural fermentation (0 h–96 h) of toddy. During fermentation, alcohol content of the fermenting saps increased significantly from 0.6 %±0.15 to 5.6 %±0.02, pH decreased from 6.33 %±0.02–3.93 ± 0.01, volatile and titratable acidity acidity (g/100 mL) increased from 0.17 ± 0.02 (0 h) to 0.48 ± 0.02 (96 h) and 1.30 ± 0.005 (0 h) to 2.47 ± 0.005 (96 h), respectively. Total sugar content and ˚BRIX also decreased during the fermentation. Firmicutes (78.25 %) was the most abundant phylum followed by Proteobacteria (21.57 %). Leuconostoc was the most abundant genus in the early stages of fermentation. However, Lactobacillus and Gluconoacetobacter were found abundant with increase in pH during the later phases of fermentation (72 h–96 h). Ascomycota (99.02 %) was the most abundant fungal phylum. Hanseniaspora was the abundant yeast in the initial stages of fermentation, whereas the population of Saccharomyces increased significantly after 24 h of fermentation. Torulaspora, Lachancea and Starmerella showed their heterogeneous distribution throughout the fermentation. Computational analysis of metagenomes based on KEGG and MetaCyc databases showed different predictive functional profiles such as folate biosynthesis, glutathione metabolism, terpenoids biosynthesis and biosynthesis of amino acids with significant differences between the fresh palm saps and fermenting saps during toddy fermentation.