Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

SCREENING AND ISOLATION OF COLD-ADAPTED CELLULOLYTIC BACTERIA FROM EXTREME HABITATS - PRODUCTION AND OPTIMIZATION OF CULTURE CONDITIONS

KODAPARTHI ASHWITHA, PAVAN KUMAR PINDI AND A. SWAROOPA RANI

Abstract

Cellulases are those hydrolytic enzymes that catalyse the total hydrolysis of cellulose into sugars. Psychrophiles are the ideal microbes for the production of enzymes active at low temperature and are also stable under alkaline conditions. The cellulases from psychrophiles also find wide applications in environmental bioremediation, laundry, food industry and molecular biology. This study is an attempt to study the diversity of psychrophilic cellulolytic bacteria, with a focus on the cellulase production and optimization of culture conditions for the best cellulase producing isolate. In the present study, a total number of 134 bacterial isolates were isolated from thesoil samples collected at 18 locations in Arunachal Pradesh and Himachal Pradesh of India. Of these isolates, 32 bacterial isolates showed hydrolysis of cellulose, and among them, AP6-C3 showed significant cellulolytic activity (zone of > 6 mm) on carboxymethylcellulose (CMC) agar plates for which the biochemical characterization was done. The 16S rRNA gene sequencing revealed the isolate AP6-C3as Bacillus sp. The optimal conditions at which Bacillus sp. showed the highest enzyme productivity was at 20 oC, pH 9 and 48 hr of incubation which may play a crucial role in this extreme environment. It was found that isolate AP6-C3 displayed specific activity of 6.89 U/mg. Ammonium sulphate precipitation followed by dialysis was performed to partially purify the cellulase enzyme. The molecular weight was found to be 35KDa by SDS-PAGE method. The results revealed the higher potentiality of these isolates to produce hydrolytic enzymes. The results obtained contribute to better understanding of the diversity of enzyme producing bacteria in cold habitats and their potential for production of hydrolytic enzymes allowing detection of promising psychrotolerant producers of industrially important enzymes.