Effect of Fermentation Response on Biosynthesis of Endopolygalacturonase from a Potent Strain of <i>Bacillus</i> by Utilizing Polymeric Substrates of Agricultural Origin

Abstract

Endopolygalacturonase (EndoPGase), EC: 3.2.1.15. is one of the crucial pectinases belonging to the class of carbohydrase. The catalytic action of EndoPGase captivates the attention of the production of this extremely valuable catalyst in the industrial sector. The main focus was to ascertain a potential bacterial candidate for endoPGase production. The isolated bacterial strain was further identified by 16S rRNA gene sequencing. The parameters for enzyme biosynthesis were optimized by a single and multiple factor approach at a time. The results of our investigation led to the identification of a potent strain of Bacillus subtilis NR2 [strain 168]. The sequence of 16S rRNA amplified from the isolated bacterium has been submitted to GenBank under accession number ON738697. The strain was found active for pectic enzyme activity under shaking- flask fermentation at pH 5.0 and 50 °C temperature of incubation. Among all monomeric and polymeric substrates (inducer-substrates), citrus pectin, followed by potato starch and pectin (Sigma) were considered the best enzyme inducers at 1% concentration. In comparison, an increased wheat bran concentration at 5% was proved to be ideal for EndoPGase biosynthesis Moreover, an increasing trend in enzyme activity was observed with the increasing concentration of inducer. The combined effect of three variables (pH, inducer-substrates, and inducer-substrate concentration) was explored by response surface methodology (RSM) involving a Box–Behnken design (BBD). Based on the results, we concluded that the soil-isolated B. subtilis can be effectively utilized for commercial-scale pectinase enzyme biosynthesis.

Keywords

• endopolygalacturonase
• biocatalysts
• biosynthesis
• heteropolysaccharide
• inducer
• submerged fermentation