Analysis and comparison of the bacterial community in fermented grains during the fermentation for two different styles of Chinese liquor

Abstract

Bacterial populations in fermented grains during fermentation may play important roles in Chinese liquor flavor. PCR-based denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene library analysis were performed to analyze the bacterial community structure of two styles of liquor. The results of DGGE profiles showed that bacterial diversity decreased with the fermentation process and Lactobacillus acetotolerans became the predominant species at the end of the fermentation. But the obvious differences of bacterial community appeared in the middle stage of two styles of liquor fermentation, in which the different upstream production techniques were used. Moreover, 16S rRNA gene libraries of two styles were constructed. A total of 125 and 107 clones, chosen from two libraries, were grouped into 46 and 49 operational taxonomic units (OTUs) by amplified ribosomal DNA restriction analysis. According to sequencing results of clones, the predominant bacteria in strong aroma style fermented grains were those from the class Bacilli, Bacteroidetes, and Clostridia, whereas the predominant bacteria in fermented grains of roasted sesame aroma style belonged to Bacilli, Flavobacteria, and Gammaproteobacteria. Molecular analysis of the bacterial diversity of the liquor fermentation will benefit the analysis of important microorganisms playing key roles in the formation of liquor flavor components.

Daqu- A Traditional Chinese Liquor Fermentation Starter

“…These are typical soil microorganisms and are not considered to be relevant for the production of liquor 22,48 . Modern culture-independent techniques have recently been used to study the microbial diversity in Zaopei (an intermediate semi-finished product in Chinese liquor fermentation) 63,64 and fermented grain 43 , but only a few such studies have been undertaken for Daqu to date 20,22 . Xie et al 53 compared fungal diversity in wheat Qu (which differs from Daqu and is used for the production of Shaoxing rice wine) using both culture-dependent and molecularbased methods.…”

Starter Culture Selection for Making Chinese Sesame-Flavored Liquor Based on Microbial Metabolic Activity in Mixed-Culture Fermentation

“…Chinese sesame-flavored liquor is one of the most popular distilled liquors in China (17). It is famous for its roasted sesame aroma and is also characterized by the solid-state and spontaneous fermentation process.…”

“…The fermentation process accumulates a specific and complex community of microorganisms, including fungi, yeasts, and bacteria. Fungal species produce amylolytic enzymes to degrade the starch in the raw material to fermentable sugars (17,18). These then become substrates for alcoholic fermentation and flavor production by yeasts and bacteria.…”

Developing New Sacchariferous Starters for Liquor Production Based on Functional Strains Isolated from the Pits of Several Famous Luzhou-flavor Liquor Brewers

“…However, liquors obtained with Fuqu often suffer from a low quality flavor and taste, which may be attributed to the lack of various functional microbes in the starters. In recent years, isolation and analysis of microorganisms in Daqu and Zaopei of famous distilleries has received considerable attention and an increasing body of knowledge in this aspect has been accumulated 8,10,16,17 . This sheds some light on elucidating the mechanisms of Chinese liquor production, and also shows the possibilities of developing new starters with functional microbes.…”