Enhanced biodiesel production from Fusarium oxysporum via mutagenesis and process optimization using bagasse...

Biodiesel offers a sustainable alternative to fossil fuels with reduced greenhouse gas emissions; however, its commercial viability is constrained by high production costs. This study aimed to develop a cost-effective strategy for enhanced lipid and biodiesel production using Fusarium oxysporum NRC 2017, cultivated on sugarcane bagasse hydrolysate enzymatically saccharified by Bacillus cereus 3SME, as an inexpensive carbon source.

To improve lipid accumulation, the fungal strain was subjected to chemical and physical mutagenesis using gamma radiation (Ɣ-rays), ethidium bromide (EtBr), ethyl methane sulfonate (EMS), and sodium azide (NaN₃). Genetic variation between the wild type and induced mutants was confirmed by inter-simple sequence repeat (ISSR) analysis. The highest lipid-producing mutant, F. oxysporum NRC 2017-1, derived from gamma radiation, was selected for further optimization. Critical process parameters were optimized using response surface methodology (RSM) to maximize lipid yield.

Under optimized conditions, the mutant strain achieved a maximum lipid yield of 3.81 g/L, representing a substantial increase over the wild type. Gas chromatography analysis revealed a favorable fatty acid methyl ester (FAME) profile, dominated by C16-C18 fatty acids, which meets the key compositional requirements for high-quality biodiesel. Furthermore, the physicochemical properties of the produced biodiesel, including cetane number, viscosity, and density, were within the recommended limits of international standards (ASTM D6751 and EN 14214).

This study presents an integrated and sustainable approach combining strain improvement via mutagenesis, valorization of lignocellulosic agricultural waste, and statistical process optimization. The findings highlight the potential of F. oxysporum NRC 2017-1 as a promising candidate for scalable, cost-effective biodiesel production.