Optimization of mutant strains of Rhizopus oligosporus lipases for sustainable biodiesel production and other eco-friendly industrial applications using non-edible oils as substrates

Lipases from Rhizopus oligosporus and their mutant variants have significant potential for industrial applications, particularly in biodiesel production and biotechnology. This study has focused on optimizing lipase production and evaluating its performance in biodiesel synthesis, as well as on investigating the effects of fermentation methods, mutagenesis, and enzyme applications.

A comparative analysis of solid-state fermentation (SSF) and submerged fermentation (SmF) revealed that SmF, at 30 °C, pH 6.5, with 1% oil and 1.5 mL inoculum, yielded maximum lipase production, making it the preferred method. Using ethyl methane sulfonate (EMS) and methyl methane sulfonate (MMS), chemical mutagen, a mutant strain of R. oligosporus was developed, resulting in a 79% increase in lipase production when almond meal was used as the substrate. The enzyme was partially purified using ammonium sulfate precipitation, with SDS-PAGE confirming a molecular weight of 35 kDa. Lipase was applied in biodiesel production through transesterification of pre-treated waste cooking oil with methanol, achieving optimal conditions at 160 rpm and 40 °C for 48 h. Biodiesel yield was confirmed using thin-layer chromatography (TLC), Fourier transform infrared (FTIR) spectroscopy, and gas chromatography (GC).

This study demonstrates the potential of R. oligosporus lipases as efficient biocatalysts for biodiesel production and other industrial applications. The successful optimization of fermentation conditions, development of high-yield mutant strains, and application in biodiesel synthesis demonstrate the enzyme’s versatility. These findings contribute to the advancement of green biotechnology and the promotion of sustainable industrial processes.