Screening of enzyme-producing strains from traditional Guizhou condiment

Abstract

Broad bean sauce with chili (BBSC) is a traditional condiment in Guizhou province of China. In order to solve some problems especially lack of dominant strains during the fermentation of BBSC, enzyme-producing strains were screened and identified from BBSC. The counts of bacteria, yeasts and molds achieved a relative equilibrium at the later period of fermentation, with more than 2.6 × 104 CFU/mL. There were 97 dominant strains obtained through isolation and purification. Besides, 16S rDNA, ITS, and 26S DNA sequences were analyzed in combination with morphological classification. The protease and peptidase activity of bacteria was significantly higher than those of yeast and molds (p < 0.05). The protease activity values of three strains were up to 137.040 U/mL, 165.560 U/mL and 103.290 U/mL, respectively. The strains could grow both in low acid and high salt environment (at pH 3 and NaCl 18%) and the number of viable bacteria could still remain more than 3.41 × 107 CFU/mL. They all showed sensitivity or high sensitivity to six kinds of commonly used antibiotics (piperacillin, erythrocin, sulfamethoxazole, norfloxacin, chloramphenicol and amikacin). So they could be used as safe fermentation strains which could facilitate upgraded industrial BBSC productions and make a controlled fermentation instead of the traditional process.