Production, purification and characterization of endo-polygalacturonase using novel strain of Bacillus pumilus through RSM

Abstract

Polygalacturonases (PG) are the enzymes that cause depolymerization of pectin. In current study, bacterial strain was isolated from rotten sample and then purified. It was screened for endo-polygalacturonase activity using PSAM media. It had shown positive response for endo-PG activity. Bacterial DNA was isolated and 16 S rRNA gene amplification was done using universal primer pair of 8 F and 1492 R. Bacterial strain was also amplified by 16 S rRNA gene for sequencing. BLAST of gene sequence on NCBI database had shown that bacterial isolate was identified as Bacillus pumilus. Endo-polygalacturonase enzyme was produced by submerged fermentation to optimize culture conditions by RSM in JMP-12 software. The optimized parameters had shown maximum endo-polygalacturonase activity of 153.2 U/mL/min after using 3 g of orange peels as substrate, 3 mL of inoculum size, 6.5 pH buffer, 40°C temperature and 3 days of incubation. After optimizing fermentation conditions, endo-polygalacturonase was precipitated using 70 % concentration of ammonium sulfate. This partially precipitated sample was dialyzed with dialysis tube and used to find activity of endo-polygalacturonase (1620.6 U/mL/min). This sample was applied to gel filtration chromatography for further purification. Endo-polygalacturonase activity increased many times 2231.44 U/mL/min after gel filtration. The Molecular weight of endo-polygalacturonase was 46 kDa after SDS PAGE characterization. High Vmax value and alkaliphilic nature of endo-polygalacturonase will make it good candidate for food and feed industry near future.