Overexpression of Chitinase A Gene from Serratia marcescens in Bacillus subtilis and Characterization of Enhanced Chitinolytic Activity

Abstract

Chitinase enzymes possess various usages in agriculture, biotechnology and medicine due to their chitin degrading property. Thus, efficient production of chitinase enzymes with desired properties has importance for its use. In this study, chitinase A (chiA) gene from Serratia marcescens Bn10 was cloned and heterologously overexpressed using pHT43 vector in Bacillus subtilis 168. The recombinant chitinase was characterized in terms of temperature, pH, and various effectors. The extracellular chitinase activity in recombinant B. subtilis was found 2.15-fold higher than the parental strain after 2 h of IPTG induction. Optimum temperature and pH for the extracellular chitinase activity in the recombinant B. subtilis were determined as 60 ^oC and pH 9.0, respectively. NaCl, Ca²⁺, Mn²⁺, Cu²⁺, Zn²⁺, sodium dodecyl sulfate (SDS), Tween-20, and ethanol increased the chitinase activity whereas Mg²⁺ caused an inhibition. The most notable increment on the chitinase activity was provided by Zn²⁺ (3.2 folds) and then by SDS (2.9 folds). The chitinase, overproduced by the recombinant B. subtilis 168 heterologously expressing chiA, was determined to have optimum activity at high temperature and alkaline conditions as well as various effectors increase its activity. The extracellular chitinase of recombinant B. subtilis might be a promising source for agricultural, biotechnological and medical applications.

Keywords:
Bacillus subtilis; Serratia marcescens; chitinase; heterologous expression; enzyme activity