BIOCONVERSION OF LIGNOCELLULOSIC WASTE MATERIALS

Abstract

The purpose of this study was to determine the effect of high pressure steaming pretreatment followed by alkali treatment to make the lignocellulose waste material susceptible to enzymatic attack. The Mangifera indlca saw dust was subjected at high presure steaming C350 + 15 psi) for 30 min. followed by alkali treatment at room temperature in attempt to improve extent of digestibility and both methods of treatment found to be ideal. The saw dust waste, mainly consists of approximately cellulose <53 - 58%), hemicellulose C18 - 21%) and lignln C18 - 22%) . The ternary complex cellulose-lignln hemicellulose, was broken and the hemicellulose and lignln components were rendered easily extractable with water and dilute sodium hydroxide solution at room temperature, respectively. The X-ray diffraction pattern before and after the pretreatment showed a marked decrease in the ordered crystalline structure of the cellulose fibre in the raw material. Trlchoderma viride 1060 and Aspergillus wentii Pt. 2804 were found to be suitable culture for production of maximum amount of cellulase and /?-glucosidase in 13 days at 30 G. Lignln free saw dust was nearly as good a substrate for production of extracellular cellulase and f?-glucosidase by T. vlrlde and A. wentii, as pure cellulose where as, untreated saw dust found to be the poor substrate due to the presence of admixtures binding the cellulose. The equl proportion of ^-glucosidase and Ill cellulase, hydrolysed cellulose to about 80% in 48 h whereas, only with cellulase, 54.6% hydrolysis of cellulose was possible. The addition of ^3-glucosidase found to be an important step, both in terms of maximum saccharification and less incubation period. The pH 4.8 was an optimum because below and above this pH, there was and sharp decline in maximum percent saccharification. Similarly the temperature also played an important role in the hydrolysis of cellulose o and 50 G found to be ideal temperature. The glucose obtained from the cellulose found to be an cheap and exceUent substrate for single cell protein and citric acid production.