An Integrated Bioprocess Development for Biofuel Ethanol Production from Wild Grass Saccharum spontaneum Biomass
An Integrated Bioprocess Development for Biofuel Ethanol Production from Wild Grass Saccharum spontaneum Biomass
Overreliance on rapidly depleting fossil fuels and consequent environmental impact has necessitated the need for renewable energy alternatives. Lignocellulosic biomass is a promising feedstock for bioethanol production; however, its complex and recalcitrant structure significantly limit its efficient bioconversion. A one-pot consolidated bioprocess (OPCB) was developed for the effective bioconversion of holocellulose-rich Saccharum spontaneum biomass (SSB) into bioethanol using acidic deep eutectic solvent (DES) pretreatment integrated with enzymatic saccharification and fermentation. SSB was pretreated with choline chloride: oxalic acid (ChCl:O) + sodium dodecyl sulphate (SDS), followed by in situ saccharification using a DES-compatible enzyme blend from Bacillus subtilis G 2. The resultant sugary hydrolysate was subsequently fermented to bioethanol. Pretreatment and enzymatic hydrolysis conditions were optimized using Design of Experiments, resulting in a 5.4-fold enhancement in reducing sugar yield (71.9–391.1 mg/g biomass). The released sugars were efficiently fermented to produce 110.99 mg ethanol/g biomass, achieving bioconversion and fermentation efficiencies of 38.53% and 71.62%, respectively. Effectiveness of the pretreatment strategy was confirmed by physicochemical analysis. FT-IR analysis revealed the significant alterations in functional groups associated with lignin and hemicelluloses, while X-ray diffraction demonstrated a notable reduction in cellulose crystallinity, indicating enhanced amorphization of the biomass. Increased water retention capacity, surface area and cellulase adsorption reflected the enhanced biomass porosity and enzyme accessibility. SEM and NMR analysis confirmed the substantial disintegration and modification of the lignocellulosic matrix. Overall, the integrated OPCB approach effectively mitigates biomass recalcitrance and demonstrates strong potential as a sustainable and efficient platform for lignocellulosic bioethanol production.