Isolation, identification, and community diversity of microorganisms during tank fermentation of Liupao tea.

Tank fermentation is a novel approach to fermenting teas; however, the species of microorganisms present remain unclear. The microbial community composition of Liupao tea at various stages of tank fermentation was analyzed using high-throughput sequencing. Sphingomonas, Aquabacterium, Pelomonas, Acinetobacter, Blastobotrys, Aspergillus, Debaryomyces, and Aureobasidium were the predominant genera, which is different from pile fermentation. Fifteen genera (including Lactobacillus, Debaryomyces, Candida, Allobaculum, Flavobacterium, Caulobacter, Blastobotrys, Aspergillus, and Rasamsonia) were identified as biomarkers. PICRUSt analysis predicted that the most abundant functional genes were related to metabolism of carbohydrates, amino acids, cofactors, vitamins, and other secondary metabolites. Using the pure culture method, 283 strains were isolated at various stages of fermentation, representing 20 genera and 29 species of bacteria, and 11 genera and 18 species of fungi. Most of the dominant Sphingomonas, Staphylococcus, Aspergillus, and Blastobotrys identified by sequencing were also isolated. Of these, Sphingomonas olei, Aspergillus luchuensis, Aspergillus niger, Aspergillus aculeatus, Aspergillus amstelodami, Blastobotrys adeninivorans, Candida metapsilosis, and Candida blankii were beneficial strains that might be used to ferment Liupao tea. This study provides a basis for the development of processing technologies and utilization of microbial strains in the production of dark teas. PRACTICAL APPLICATION: Microbial diversity in tank-fermented Liupao tea was reported for the first time. 8 microorganisms were the predominant genera. The species, functions and potential risks of microorganisms was revealed. We clarified the differences between tank and pile fermentation.