Valorization of glycerol into value-added products: A comprehensive review on biochemical route

With the advancement of technology, fossil fuels are used at an alarming rate leading to a scarcity of conven-tional fossil fuels. Biodiesel seems to be the best alternative shortly; one problem associated with biodiesel is the generation of excessive glycerol, which can significantly threaten the environment by accumulation in large quantities. Glycerol can be converted to other high-value products using chemical and biological conversion. The chemical pathway is less preferred because of being uneconomical and environment unfriendly compared to the bioconversion route. The bioconversion route is a promising alternative for glycerol valorization and can make biodiesel industries economically sustainable and environment-friendly. This review focuses on current novel and genetically modified microorganisms that can use crude glycerol as a carbon source and convert glycerol into various valuable products.