Isolation and selection of Bacillus sp. with the potential biosynthesis of protease from fermented soybean products

Abstract

This study aims to isolate and select strains of Bacillus for protease production from fermented soybean products. To evaluate the ability of protease production, the authors applied the hydrolysis diameter measurement method on Skim milk agar (SMA) and submerged fermentation (SmF). The results showed that 29 bacterial strains were isolated from fermented soybean products in An Giang and Can Tho provinces. Based on the morphological and biochemical characteristics of bacteria, these are defined belong to the Bacillus genus. The results of the protease generation test on SMA helped to select eight strains with a high halo diameter. In SmF with 106 cells/ml, pH 7.2, at 37°C for 48 hours, the ML01 strain gave the highest specific protease activity of 185.92 U/mg. Sequence analysis results of the 16S rRNA gene region of ML01 exhibited a high relationship with the sequence of Bacillus subtilis.