New Perspectives in Sustainable Bioconversion of Lignocellulose to Biofuel by Diatoms

Organic carbon may be obtained sustainably from lignocellulosic biomass; however, the majority of microorganisms, including microalgae, find it difficult to convert it through bioconversion due to its refractory nature. As a result, a significant challenge lies in the bioprospecting and metabolic engineering of microalgae to use lignocellulosic carbohydrates including cellulose, hemicellulose, and lignin with minimal pretreatment. Diatoms that are heterotrophic epiphytic are capable of consuming organic matter as they can naturally produce cellulolytic and hydrolytic enzymes, allowing them to effectively use lignocellulose for growth. They have a unique carbon metabolism which, due to the presence of enzymes, is exclusively involved in the breakdown of lignin via the β-ketoadipate pathway. This chapter focuses on how diatoms convert lignocellulose to produce biofuels and other value-added products that can help to achieve a sustainable environment in the near future.