Screening of Bacillus strains from Luzhou-flavor liquor making for high-yield ethyl hexanoate and low-yield propanol

This study aimed at isolating and culturing Bacilli from the omagari, pit mud, and fermented grains used in Luzhou-flavor liquor in an effort to produce better flavor and quality. After an enrichment culture of Bacillus in the omagari, pit mud, and fermented grains of Luzhou-flavor liquor, 52 total strains were obtained. Based on the standard of producing high-yield ethyl hexanoate and low-yield propanol, one strain named YB-1 was screened out. It was shown that YB-1 produced ethyl hexanoate at 214.7 mg/100 mL and propanol at 0 mg/100 mL. Based on strain morphology, and physiological and biochemical characteristics, YB-1 was identified as Bacillus. According to DNA sequencing and the constructed phylogenetic tree, YB-1 and Bacillus cereus strain CCM 2010 clustered into a branch and were each other's closest relatives. Thus, YB-1 was identified as Bacillus cereus. Through this research, it is expected that the application of Bacillus cereus strain YB-1 to the traditional brewing process of Luzhou-flavor liquor could improve the flavor and quality, and enrich microbial resources for Luzhou-flavor liquor fermentation.