Glycerol bioconversion to biofuel and value-added products by yeasts.

Glycerol, a by-product of biodiesel production, is a versatile polyol used in various industries. Yeasts play a crucial role in converting glycerol into biofuels and value-added products, offering sustainable alternatives to chemical synthesis. This review explores glycerol metabolism in yeasts, focusing on its bioconversion into ethanol, isopropanol, lipids, organic acids, and polyols. Saccharomyces cerevisiae and Yarrowia lipolytica are prominent species for these processes, with metabolic engineering enhancing their efficiency. Ethanol production from crude glycerol, a by-product of the biodiesel industry, is cost-effective compared to traditional feedstocks, while lipid production by oleaginous yeasts supports biodiesel synthesis. Organic acids like succinic, citric, and lactic acids, along with polyols such as erythritol and mannitol, are produced through optimized pathways, achieving high yields. Crude glycerol, despite impurities, is a viable low-cost substrate, with yeast strains adapted to tolerate its contaminants. Challenges include improving strain tolerance and scaling up processes. Future research aims to refine metabolic engineering and fermentation strategies to maximize glycerol's potential as a renewable feedstock for industrial biotechnology.