Bacterial diversity in the central black component of Maotai Daqu and its flavor analysis

Maotai Daqu (MTDQ) is a kind of microflora starter for making the distilled liquor Maotai. It mainly contains bacteria, yeasts and moulds. When it comes to its central black component, it is nearly all bacteria. This study aims to clarify the bacterial diversity of the central black component of MTDQ, to analyze the role bacteria plays in Maotai liquor brewing, and to study the flavor components produced during the mixed solid-fermentation of three of the predominant flavor-producing bacteria so as to develop their practical application in other industries. Bacterial diversity was studied using amplified ribosomal DNA restriction analysis; Actinobacteria and Firmicutes were the predominant bacteria. The three flavor-producing strains were identified as Bacillus subtilis, B. licheniformis and B. amyloliquefaciens, which are the predominant bacteria. Their fermentation products include propanoic acid, 1,3-butanediol, acetic acid, methyl ester, etc. Most of which are analogous to the main flavor components of Maotai liquor. The results imply that the sample has diverse bacterial communities. Some bacteria play a very important role in the formation of the unique wine body composition of the Maotai liquor through their biotransformation, and some could be the main origins of the flavor of Maotai-type liquor.