Bacterial communities during the process of high-temperature Daqu production of roasted sesame-like flavour liquor

Bacterial communities in fermentative high-temperature Daqu play an important role in the Chinese roasted sesame-like flavour liquor brewing process. A culture-independent method of 16S rDNA clone library was applied to investigate the changes in bacterial diversity during the process of a Daqu fermentation. The results indicated that the types of bacteria species gradually increased with prolonged fermentation time. The first dominant bacterium, Pantoea sp. (73.68%), in the raw material was only detected at the beginning of the fermentation stage (8 days) in small quantities. The second dominant bacterium, Weissella sp. (16.99%) and the third, Lactobacillus sp. (4.57%), were both detected in the beginning fermentation sample (3.22, 11.29%), in the ripening fermentation sample (24 days; 6.89, 25.11%) and in the drying stage (49 days; 3.74, 7.47%). In the beginning fermentation, Thermoactinomyces sp. (47.57%) was detected as the first predominant bacterium, and it was also detected in the ripening fermentation stage (4.93%) and in the drying stage (15.68%). The bacterial communities in the Daqu fermentation process affected the physicochemical index of Daqu. A molecular analysis of the bacterial community from the Daqu fermentation process will benefit studies on the aroma production mechanisms from these bacteria.