Diversity of lactic acid bacteria in Moutai-flavor liquor fermentation process

ABSTRACT Maotai-flavor liquor, derived from a multi-stage solid fermentation process, is one of the most popular liquors in China. Its quality and flavor are closely related to diverse lactic acid bacteria (LAB). It is therefore significant to characterize LAB for the manufacturing of Maotai-flavor liquor. In this study, LAB in solid state fermentation stages were analyzed through high-throughput sequencing and cultivation-dependent methods during the fermentation process. In total, 65 LAB species were identified in the fermented matrix, showing a much higher LAB diversity than other types of Chinese liquor. In addition, discrepancies were found to exist in the dominant LAB community structures during different fermentation stages, and strains of the Lactobacillus genus were found to be the most dominant LAB. Furthermore, 33 LAB species were identified from the fermentation matrix through the cultivation and 16 S rRNA analysis of single isolates, thus representing 50.8% coverage of the detected LAB species. The relative abundance of isolated LAB in the total abundance of LAB was 95.9% during the fermentation process. In doing so, Lac2 and Lac13, two potentially new LAB species, were isolated. To the best of our knowledge, this study represents the identification of the highest number of LAB species by cultivation-dependent methods from fermented grains of Chinese liquor. In summary, this study monitored the LAB species composition of solid fermented matrix during the fermentation of Maotai-flavor liquor and has highlighted the potential importance of the higher abundance of LAB and the effect it has on the unique flavor of Maotai liquor.