Bioprospecting of microbial strains for biofuel production: metabolic engineering, applications, and challenges

Abstract

The issues of global warming, coupled with fossil fuel depletion, have undoubtedly led to renewed interest in other sources of commercial fuels. The search for renewable fuels has motivated research into the biological degradation of lignocellulosic biomass feedstock to produce biofuels such as bioethanol, biodiesel, and biohydrogen. The model strain for biofuel production needs the capability to utilize a high amount of substrate, transportation of sugar through fast and deregulated pathways, ability to tolerate inhibitory compounds and end products, and increased metabolic fluxes to produce an improved fermentation product. Engineering microbes might be a great approach to produce biofuel from lignocellulosic biomass by exploiting metabolic pathways economically. Metabolic engineering is an advanced technology for the construction of highly effective microbial cell factories and a key component for the next-generation bioeconomy. It has been extensively used to redirect the biosynthetic pathway to produce desired products in several native or engineered hosts. A wide range of novel compounds has been manufactured through engineering metabolic pathways or endogenous metabolism optimizations by metabolic engineers. This review is focused on the potential utilization of engineered strains to produce biofuel and gives prospects for improvement in metabolic engineering for new strain development using advanced technologies.

Keywords: CRISPER/Cas9; Fermentation; Lignocellulose; Metabolic pathways; Microbial cell factories; Model strains.

Fig. 1

Lignocellulosic biomass structure

Fig. 2

Degradation of hemicellulose by xylanases

Fig. 3

Flowchart of bioethanol production from lignocellulosic biomass

Fig. 4

Pentose metabolism and Entner–Duoduroff pathways in transformed Zymomonas mobilis