Fungal Enzyme Hydrolysis of Agricultural Biomass Wastes: Comparative Studies of Different Lignocellulosics

Abstract

Environmental pollution from agricultural activities remains a challenge, especially in developing economies. Due to recalcitrance to hydrolysis, such byproducts tend to persist in the environment owing to their high lignocellulose content. Alternatively, eco-friendly hydrolytic approaches are imperative to mitigate environmental pollution. Besides, hydrolysis holds promise for reducing sugar production, which could serve as a starting material for bioethanol production towards a clean energy future and sustainable energy production. Some of the abundant agro-byproduct biowastes come from sugarcane, rice husks, and groundnut. To this end, five varieties of sugarcane, namely National Cereals Sugarcane (NCS)-, NCS-003, NCS-006, NCS-007, Coimbatore 957, and a local variety, besides rice husk and groundnut shells, were studied for ease of fungal cellulase degradation and hydrolysis for reducing sugar production, using isolated wild strains of Aspergillus niger and Spadicoides spp, using established methods. Extracellular enzyme production potential was assessed by measuring the protein secretion capacity of the fungal strains in broth culture. Spadicoides spp produced 1.23 mg/mL and 0.38 mg/mL of extracellular protein when grown on NCS-003 (W) and rice husk, respectively. Aspergillus niger grown on NCS-003 (W) and NCS-007 (UW) secreted extracellular proteins of 0.98 mg/mL and 0.50 mg/ml, respectively. Co 957 and Local showed an almost linear relationship between activity and substrate concentration. Reducing sugar production was highest in Local (192.22 activity units) and least in NCS-003 (78.33 units). Therefore, Local was adjudged the SCB with the highest potential for fungal cellulase-mediated biodegradation to reduce sugar production.