Optimization of Process Conditions for the Production of Holocellulase by a Bacillus Species Isolated from Nahoon Beach Sediments

Abstract

Production of holocellulase by a newly isolated marine Bacillus species via submerged fermentation technique at varying cultivation conditions was investigated. Enzyme production was optimized by altering one variable per time. Moreover effect of lignocellulosic saccharides in inducing cellulase and xylanase production was also investigated. The 16S ribosomal Deoxyribonucleic Acid (16S rDNA) gene sequence analysis exhibited 98% sequence similarity of the isolate with other Bacillus species in the gene bank and was deposited with the accession number KX524510. Optimal xylanase and cellulase production was attained at pH 7, temperature 30°C and agitation speed of 50 and 150 rpm. Furthermore, maximum xylanase and cellulase production were both achieved at 60 h corresponding to the late stationary growth stage, with activity of 16.6 and 0.061 U mL^-1 respectively. Xylanase production was maximally induced by beechwood xylan, xylose and arabinose with activities of 13.59, 8.78 and 1.90 (U mL^-1) respectively; while cellulase production was induced by carboxymethyl cellulose only and no cellulase activity was detected in the culture supernatant of the other carbon sources tested. Optimization increased cellulase and xylanase yields being 0.006-0.061 and 0.23-16.6 (U mL^-1) from unoptimized to optimized respectively. The results of the study suggest the bacterial strain to be a proficient producer of cellulase and xylanase with potentials in biotechnological application.