Original Articles
Ikram-ul Haq
Abstract
Bacillus strains have wide distribution from soil to plants to digestive system of animals including human. Most of its strains produces xylanases enzymes that are being useful in pulp and paper industries as well as biotransformation of hemicellulose to simple carbons molecules. In nature, celluloses and hemicelluloses in plants are most abundant complex carbon source on earth. The xylanases hydrolysis β-1,4-D xylan bonding of the hemicellulose. Among bacteria, xylanases shows diverse activities under environmental extremophile conditions. In this comparative study, xylanase activity was assessed in six Bacillus wild-type strains i.e. B. amylolique faciens, B. cereus, B. licheniformis, B. pumilus, B. thuringiensis, B. subtilis 168 under low to high pH and temperature stressed conditions. Cell culture of these strains was raised in BXN (supplemented 0.5% xylan) liquid medium of 20-hrs of incubation with 250 rpm shaking at 37°C. Maximum cell multiplication was observed in B. pumilus and B. cereus while total proteins in cell culture of B. cereus and B. subtilis 168.Higher xylanase activity was observed in B. pumilus(9.669±0.003 U.ml-1) and B. cereus (8.319±0.003 U.ml-1). The enzyme stability was observed in B. pumilus that showed 1.251±0.003 U.ml-1 and 0.420±0.002 U.ml-1 activities in acidic (pH 4.5) as well as basic (pH 10.0) from low (28°C) to high (50°C)temperature stressed conditions respectively. Comparative analysis of this study suggests, B. pumilus and B. cereus produces stable xylanase that could be suitable source of industrial point of view. In general, B. subtilis 168 isnon-pathogenic and best extracellular protein producer. It might be nicer to use B. subtilis 168 for the production of stable xylanasesand helpful in industrial revolutionization.