Studies on Salt Tolerance of Bacillus Isolated from the Industrial Soy Sauce Residue

Abstract

The annual output of soy sauce was reported to be more than 4.4 million tons in China, which would threaten the environment with its high salinity. The Bacillus in this study were isolated from soy sauce residue, which would contribute to its recycling. This study aims to investigate the external and internal characteristics of salt tolerant B. cereus stains (B-25 and B-26) to enhance the utilization of industrial soy sauce residue, with the methods of modified plate counting and whole genome analysis, respectively. Both B-25 and B-26 have the ability of salt-tolerance, and B-25 has a stronger salt-tolerant capacity. A total of 49 salt-tolerance related genes were identified by whole genome resequencing and bioinformatics analysis and were verified by PCR. Study on the external and internal characteristics of salt tolerant B. cereus strains will improve the understanding of salt-tolerant mechanism of B. cereus and further aid in the control of spoilage bacteria and the quantity and quality of the production in soy sauce residue industry.