Properties of Bacterial Cellulases and Secondary Metabolites of Cellulolytic Bacterial Fermentation of Rice Husks
F. O. Onwuka
Department of Microbiology, Faculty of Science, University of Lagos, Lagos, Nigeria
F. A. Orji *
Department of Biotechnology, Federal Institute of Industrial Research, Oshodi, P.M.B. 21023, Ikeja, Lagos State, Nigeria
R. E. Uzeh
Department of Microbiology, Faculty of Science, University of Lagos, Lagos, Nigeria
E. O. Ugoji
Department of Microbiology, Faculty of Science, University of Lagos, Lagos, Nigeria
*Author to whom correspondence should be addressed.
Abstract
The unchecked accumulation of rice husk which is one of the agro-industrial wastes on land serves as source of environmental pollution. This present study showed that submerged fermentation of rice husk for cellulase production and extraction of secondary metabolites was successful using bacterial isolates. The identities of the cellulase hyper-producing strains were Bacillus subtilis strain SDDlas, Bacillus amyloliquefaciens strain CF11, Bacillus cereus strain AT and Bacillus amyloliquefaciens. The partial purification of cellulase was achieved by Protein precipitation using ammonium sulphate fractionation, and membrane dialyses. The metallic salts CaCl2, MgSO4 and FeSO4 activated cellulase activity whereas CuSO4 inhibited it. The compounds common to the four Bacillus strains at zero hour are: 9,17-Octadecadienal and propanal while secondary metabolites found after seven days fermentation are cis-13-Octadecanoic acid, pentadecanoic and di-isoctyl phthalate. These organic acids are of industrial importance in pharmaceutical and cosmetic industries.
Keywords: Fermentation, secondary metabolites, cellulase and fermentation