Pilot scale production of recombinant hemicellulases and their saccharification potential

Synergistic saccharification ability of hemicellulases (endo-xylanase and β-xylosidase) was evaluated in this study for the bioethanol production from plant biomass. Endo-xylanase and β-xylosidase genes from Bacillus licheniformis were cloned and expressed in Escherichia coli BL21 (DE3). Maximum endo-xylanase production was obtained at 200 rpm agitation speed, air supply rate 2.0 vvm, 70% volume of the medium, 20% dissolved oxygen level and with 3% inoculum size. The optimal conditions for maximum production of recombinant β-xylosidase enzyme at pilot scale were 200 rpm agitation speed, 25% dissolved oxygen level, 2.5 vvm aeration rate, 70% volume of the medium with 2% inoculum size. Furthermore, the saccharification potential of these recombinant enzymes was checked for the production of xylose sugar by bioconversion of plant biomass by optimizing individually as well as synergistically by optimizing various parameters. Maximum saccharification (93%) of plant biomass was observed when both enzymes were used at a time with 8% sugarcane bagasse as a substrate and 200 units of each enzyme after incubation of 6 hr at 50 °C and 120 rpm. The results obtained in this study suggested these recombinant hemicellulases as potential candidates for the conversion of complex agricultural residues into simple sugars for ultimate use in the biofuel industry.