Advances in microbial biofuel production by metabolic and enzyme engineering, synthetic biology, metagenomics, and genome editing applications.

Microorganisms are the primary source of genetic diversity on earth due to their unparalleled metabolic and functional variability. With the depletion of fossil fuels, a sustainable alternative approach is the use of biofuels, where plant biomass as feedstock is essentially degraded to sugars with the aid of microbe-derived enzymes, followed by the conversion of those sugars to biofuels. Several cellulolytic and non-cellulolytic enzymes are involved in biofuel synthesis. Molecular cloning, along with the advancements in genetic and metabolic engineering in microbial cells, plays a significant contribution to biofuel overproduction. Advanced molecular technologies such as metagenomics and synthetic biology approaches are also being used to construct effective microorganisms for biofuel manufacturing. Obtaining novel enzymes from undiscovered microbial consortia and functional gene analysis is possible through a metagenomics approach. While synthetic biology provides engineered biological systems to generate required biofuel productivity, the CRISPR-Cas genome editing tool is another revolutionary tool being utilized for efficient biofuel production. This article provides a brief overview of different methods of biofuel production using microorganisms.