Engineering cellulolytic fungi for efficient lignocellulosic biomass hydrolysis: advances in mutagenesis, gene editing, and nanotechnology with CRISPR-Cas innovations

Abstract The increasing global energy demand and environmental concerns have highlighted the need for sustainable and renewable energy sources. Lignocellulosic biomass (LCB), rich in cellulose, hemicellulose, and lignin, is a promising resource for biofuel production. However, the recalcitrant nature of lignin poses a significant challenge by obstructing effective LCB decomposition. This review provides a comprehensive analysis of recent advancements in genetic and metabolic engineering techniques, focusing on directed and random mutagenesis to enhance cellulase production in fungi. It explores how these techniques can overcome challenges in lignin degradation and improve LCB conversion efficiency. Lignin's high resistance to degradation, due to its complex association with cellulose and hemicelluloses, necessitates the development of advanced fungal strains through mutagenesis. Fungi, which are efficient lignin degraders, benefit from these practices to enhance enzyme production and address environmental pollution from burning LCB. The review emphasizes engineering cellulolytic fungi through mutagenesis, gene-editing, and synthetic biology, highlighting CRISPR-Cas innovations and nanoparticle-based delivery systems for precise CRISPR-Cas application. It also discusses the role of transcription factors in boosting enzyme production and the practical applications of these techniques for in-situ LCB biodegradation. Effective implementation of these advancements could foster a sustainable economy and mitigate the negative environmental impacts of current agricultural practices.