Comparative Genomics of Bacillus Subtilis MZK05 and Its Mutant Strain Revealed Genetic Factors Responsible for Enhanced Serine Protease Expression

Abstract

Genome sequence study of an industrially-important strain, Bacillus subtilis M9, a mutant version of wild strain Bacillus subtilis MZK05 was conducted to uncover genetic factors responsible for enhanced serine proteases expression in addition to its other industrial enzymes, metabolites and bacteriocins producing efficacy. The wild type and the mutant genome contained a size of 4,145,727 and 4,045,950 bp, with 4,352 and 4,383 genes; and 477 and 478 subsystems respectively. Genomic comparison with 31 B. subtilis sourced from different countries showed both wild and mutant shared same type of genome structure with 20 others. Moreover, 6,000 kb pangenome showed that they share 3082, 1449, and 25757 core, unique and accessory genes respectively. A sum of 32,559 mutations were found with three major genomic structural changes in the upstream and downstream of an extracellular alkaline serine protease, AprX and a periplasmic serine protease, HtrC in M9 genome when compared to the wild type. Furthermore, 11 different serine protease genes and 4 different signal peptidases were found with several mutational changes in M9. In addition, mutations found in core genome of BsM9 in phage-like element, major capsid protein, and phage portal protein are the likely reasons of high-level serine protease activity.