Production and Optimization of Alkaline Pectin Lyase fromBacillus cereusUnder Submerged Fermentation

Abstract

Bacillus cereus was isolated from soil sample and selected as maximum pectin lyase producing bacterium under alkaline conditions. The morphological, cultural and biochemical characteristics of bacterium were studied and it was identified on the basis of nucleotide homology and phylogenetic analysis by 16S rDNA analysis. Pectin lyase gave considerable activity with pectin (3% w/v) as a sole carbon source, there was a significant increase in enzyme activity (p<0.001). A combination of both yeast extract and peptone (0.5% w/v each) as nitrogen source also showed significant increase in enzyme activity (p<0.001). Enzyme gave maximum activity with inoculum age of 18 h, inoculum size of 2% (v/v), at temperature of 40°C and pH 10.0 for 24 h incubation time. The glycine-NaOH buffer (0.25M) of pH 10.0 was found to be the most appropriate buffer and optimum reaction temperature and incubation time observed were 30°C and 55 min respectively. Enzyme showed greater affinity towards pectin (0.5% w/v) as substrate. Among all the metal ions studied only Mn2+ ion was effective to stimulate the activity whereas other metal ions inhibited the enzyme activity. SDS was found to be the strongest inhibitor and among thiols, L-cysteine and ascorbic acid stimulated enzyme activity. All the phenolics studied inhibited the enzyme activity. The enzyme gave half-life of 150 min at optimized pH 10.0. Optimal enzyme concentration observed was 0.01mg/ml. This enzyme has tremendous potential in textile industry and paper and pulp industry.