Enzymatic saccharification of sugar beet pulp by novel mutants of Trichoderma reesei NRCAM 5 for bioethanol production

Fuel ethanol production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable production of renewable transportation fuels. Sugar beet pulp (SBP) represents a major source of lignocellulosic material (LCM) with considerable potential for use in biomass conversion to ethanol. In this study, Trichoderma reesei and novel mutant of T. reesei NRCAM5 were used for extracellular enzymes production from sugar beet pulp and subsequent fermentation of sugars to ethanol by Saccharomyces cerevisiae and kluyveromyces marxianus. Endo-glucanase, exoglucanase, β-glucosidase, pectinase and invertase activity was investigated. Also, the purity and composition of enzyme-rich protein samples were evaluated under denaturing conditions by SDS-PAGE. Mutant T. reesei NRCAM5 produces high levels of cellobiase, which can be further improved by controlled culture conditions. In addition, this mutant strain produces good levels of exoglucanase, endoglucanase and FPase, which together with the exceptionally high levels of cellobiase, makes it a good candidate for obtaining cellulases for saccharification of SBP. The T. reesei and T. reesei NRCAM5 have both enzyme bonds of Cel6A (CBHII) and Cel7A (CBHI). The highest synergy was observed in FPase of T. reesei NRCAM5, that containing of large amount of CBH I and CBH II and minor amount of EG. The results indicated that the higher ethanol concentration can be obtained from the enzyme hydrolyzed sugar beet pulp by T. reesei NRCAM5. This can be explained to the fact that T. reesei NRCAM5 can affect the cellulosic region differently and hence facilitates the enzyme treatment and thus the fermentation to produce the ethanol.

Keywords:

Trichoderma reesei , γ-irradiation , SDS-Page , Sugar beet pulp , Cellulase