De-Escalation of Saccharification Costs through Enforcement of Immobilization of Cellulase Synthesized by Wild Trichoderma viride

Abstract

The economic uncertainty associated with cellulosic bioethanol can be overcome through the inclusion of cheap substrates and methodologies that can extend the shelf life of cellulolytic enzymes. In this study, wild Trichoderma viride was used to produce cellulases, media formulation studies were conducted to enhance the cellulase production further and immobilization strategies were tested for stable cellulase–iron oxide magnetic nanoparticle coupling. Out of the seven different production media designed, media containing glucose, wheat bran, cellulose and corn steep liquor supported the highest biomass growth (60 Packed cell volume) and cellulase formation (7.4 U/mL), and thus was chosen for the fiscal analysis at a larger scale (1000 m3). The profitability of the cellulase production process was assessed to be 20.86%, considering both the capital expenditure and operating expenses. Further, the effect of cost of different carbon sources, nitrogen sources and cellulase yields on the annual operating costs was explored, which led to the choice of delignified sugarcane bagasse, corn steep liquor and productivity levels to be respective decisive factors of the overall cost of the cellulase production. Likewise, the break-even period of such a large-scale operation was gauged given the market price of cellulases at USD 17 for 105 U of cellulases. Moreover, enzyme immobilization led to enhanced cellulase shelf life and ultimately contributed toward saccharification cost reduction.