Synergistic effect of Ce-based nanocatalysts in the pretreatment and saccharification of raw lignocellulosic biomass: an advancement in bioethanol production

This study presents a sustainable one-step process for converting raw sugarcane bagasse (SB) into bioethanol, highlighting the innovative use of cerium-doped iron oxide nanoparticles (CeFe₃O₄NPs). Initially, these nanoparticles facilitated simultaneous pretreatment and hydrolysis of the raw SB biomass under ambient conditions (50 °C), demonstrating direct catalytic activity by producing 6.55 ± 0.112 g/L glucose and 4.73 ± 0.143 g/L xylose within 24 h. The scalability of this approach was confirmed with similar results achieved in a larger 7.5 L-scale fermentation. A key novelty of this research lies in demonstrating the synergistic effect of CeFe₃O₄NPs with enzymatic hydrolysis. By incorporating a minimal amount of in-house generated cellulase enzymes alongside CeFe₃O₄NPs, the sugar yields dramatically increased to 23.1 ± 1.12 g/L of glucose and 13.9 ± 0.88 g/L of xylose. This indicates that CeFe₃O₄NPs are not merely catalysts but function effectively as promoters, significantly enhancing the efficiency of enzymatic process. The subsequent fermentation using Saccharomyces cerevisiae efficiently converted these sugars, including xylose, into 17.3 ± 0.98 g/L of bioethanol with a productivity of 1.44 g/L/h. Further gene expression studies using quantitative real-time PCR (qRT-PCR) analysis revealed that CeFe₃O₄NPs played a role in upregulating xylose-utilizing genes within yeast strain, leading to near-complete utilization of xylose. This stimulation of xylose metabolism is a crucial finding that significantly aids in improving the overall economics of the biomass conversion process. This integrated approach, combining magnetic CeFe₃O₄NPs with enzymatic activity and xylose metabolism, represents a significant step towards more cost-effective and scalable bioethanol production from lignocellulosic biomass. KEY POINTS: • Eco-friendly bioethanol production from sugarcane bagasse using nanobiotechnology • Delignification and hydrolysis of biomass by enzyme-mimicking CeFe3O4 nanoparticles • Xylose utilization by S. cerevisiae noticed due to CeFe3O4 nanoparticles.