Cellulolytic Bacillus May or May Not Produce β -Glucosidase Due to Their Environmental Origin – A Case Study

Abstract

Microbial cellulases have been drawing attention worldwide because of their massive capacity to process the most abundant cellulosic biomass into sustainable biofuels and other valuable products. Profitable biomass conversion processes are highly dependent on the use of efficient enzymes for lignocellulose degradation. Among the cellulose degrading enzymes, β-glucosidases are essential for efficient hydrolysis of cellulosic biomass as they relieve the inhibition of the cellobiohydrolases and endoglucanases by reducing cellobiose accumulation. In this study, cellulolytic bacteria with potential β-glucosidases activity were isolated and screened from biogas plant effluent and dairy effluent near Jahangirnagar University campus. From initial screening, a total of 16 isolates were found to have cellulolytic activity, among them three isolates (B1, B5, D4) were selected based on their superior results. All the three bacterial isolates were identified as B. subtilis (B1), Bacillus amyloliquefaciens (B5) and B. subtilis (D4) respectively based on their morphological, biochemical and molecular characteristics. The βglucosidases activity of these three potential cellulolytic bacteria was performed by measuring the release of PNP using pNPG as a substrate and interestingly D4 strain was resulted with β-glucosidases negative where B1 strain was found to have efficient for β-glucosidases activity.