Screening of Bacterial Strains of Agricultural Waste Origin for Βeta-mannanase Production and Optimization of Process Parameters

Abstract

Aims: This study was carried out to screen bacterial strains of agricultural wastes origin for β-mannanase production and optimization of culture conditions. Study Design: The first experiment, bacterial strains were screened for β-mannanase production. In the second experiment, the best incubation time was determined. In the third experiment, different agricultural wastes were screened. In the fourth experiment, different nitrogen sources were screened. In the fifth and sixth experiments described the effect of different pH values and incubation temperatures on β-mannanase production. The best moisture content was determined in the seventh experiment, while in experiment eight; effect of different inoculum concentrations was evaluated.  Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure, Nigeria between September 2011 and March 2012. Methodology: Bacterial strains were screened and β-mannanase production from optimization studies was conducted on Locust Bean Gum. Enzyme activity was determined by dinitrosalicylic acid method. Results: Out of the sixteen bacterial strains screened, Klebsiella edwardsii designated 1A was selected as the most potent in producing enzyme of high activity and it was therefore selected for further studies. Pineapple peels were found to be the most effective carbon source with a highest β-mannanase activity of 8.533±0.08U/ml. Ammonium nitrate (NH4NO3) was obtained to be the best nitrogen source out of all the nitrogen sources screened. The best moisture content was obtained at 1:11 (ratio of substrate to salt solution). Inoculum concentration of 1.0% (v/v) yielded highest β-mannanase activity of 15.833±0.01U/ml. Addition of simple carbon sources to medium containing LBG caused a catabolic repression of β-mannanase synthesis. Conclusion: The optimal culture conditions obtained from this study will help to standardize the requirements for optimum β-mannanase production using cheaper substrates.