The aim of this study was to screen out a bacillus from Sichuan sun vinegar grains capable of producing a high total amount of flavonoids and total phenols. Forty-eight strains were initially screened out from Sichuan sun vinegar grains. The sodium nitrite-aluminum nitrate-sodium hydroxide colorimetry method was used to determine the total flavonoids, and the Folin-phenol method was used to determine the total phenols. Based on the results of total flavonids and total phenol producing capacities of the strains, one strain was singled out for use in this study. This strain, which was named YB-19, is capable of producing a total amount of 96.55 μg/mL flavonoids and 86.69 μg/mL phenols. YB-19 was identified by its strain morphology, physiological and biochemical characteristics. DNA sequencing was performed on YB-19. The results of the DNA sequencing showed that the sequence similarity between strain YB-19 and Bacillus toyonensis strain BCT-7112 was 99 %, and the two strains were housed on the same branch in the phylogenetic tree. Combined with the results of the strain morphology and the observed physiological and biochemical characteristics, YB-19 was identified as B. toyonensis. The screened strain YB-19 can be applied to the traditional brewing process of sun vinegar to improve vinegar quality and to enrich the microbial resources for vinegar fermentation.
Keywords: Bacillus; Flavonoids; Phenolics; Sun vinegar.