Tuesday, May 3, 2011
Lignocellulosic biomass, the most abundant organic raw material in the world, constitutes a major portion of agricultural wastes and forest wastes. These wastes are promising feedstock for the production of energy, food and chemicals. For example, this substrate could also be a potent substrate for cellulase enzyme production by cellulolytic microorganism. Cellulase enzymes provide a key opportunity for achieving tremendous benefits of biomass utilization through the bioconversion of lignocellulosic biomass into the simplest carbohydrate monomer, glucose. Agricultural wastes are example of lignocellulosic biomass that presents high cellulose content, which can be considered as substrate in producing this potential enzyme. In previous work, Bacillus subtilis TD6 has been isolated from Takifugu rubripes gut and known as natural cellulase producer. In this study, three agricultural wastes were used, including rice hulls, corncob and pineapple peel. The measurement of cellulase activity was based on DNS method. Cellulase activity by using wastes substrates was determined and optimized by varying the fermentation parameters: time, pH, temperature and substrate concentration. The results obtained from the fermentation showed that corncob stimulated higher activity of CMCase and FPase than other agricultural wastes which was 3.19 U/ml and 0.71FPU/ml, respectively. That was produced from 3% corncob on 3th day of fermentation at 6 pH and 45°C temperature. While highest CMCase activity using 2% rice hulls and 3% pineapple peel were 0.65 U/ml and 2.26 U/ml, respectively. These highest results from each agricultural waste were obtained on the same condition, 3th day of fermentation at 6 pH and 45°C temperature.