Abstract: In order to shorten the fermentation period of fermented soybean products, a total of 150 strains were isolated from top-quality fermented foods in Guizhou. Among these strains, strain WDH-8 was found to have the highest branched-chain aminotransferase activity. The strain was identified as Bacillus licheniformis that was a safe prebiotic yeast strain with a branched-chain aminotransferase activity of 36.53 U/mL. In order to facilitate practical applications, the preparation of its solid starter culture was investigated, and the optimal culture medium for achieving the highest branched-chain aminotransferase activity, 37.965 U/mL, was determined to be composed of soybean power 25 g, material-to-water ratio 1:1, sodium chloride 5% and glucose 3%.

Key words: soybean fermenting, aminotransferase, starter cultures, Bacillus licheniformis