Management of microbial enzymes for biofuels and biogas production by using metagenomic and genome editing approaches

Abstract

Non-renewable fossil fuels such as bitumen, coal, natural gas, oil shale, and petroleum are depleting over the world owing to unrestricted consumption. Biofuels such as biodiesel, biobutanol, bioethanol, and biogas are considered an eco-friendly and cost-effective alternatives of fossil fuels. For energy sustainability, the production of advanced biofuels is required. The advancement of genetic and metabolic engineering in microbial cells played a significant contribution to biofuels overproduction. Essential approaches such as next-generation sequencing technologies and CRISPR/Cas9-mediated genome editing of microbial cells are required for the mass manufacture of biofuels globally. Advanced "omics" approaches are used to construct effective microorganisms for biofuels manufacturing. A new investigation is required to augment the production of lignocellulosic-based biofuels with minimal use of energy. Advanced areas of metabolic engineering are introduced in the manufacture of biofuels by the use of engineered microbial strains. Genetically modified microorganisms are used for the production of biofuels in large quantities at a low-cost.

Keywords: Biofuels; Biogas; Genetic engineering; Metabolic engineering; Microbiome; Omics approaches.

Fig. 1

Schematic representation of culture dependent and independent methods for identifying microbial enzymes for biofuel production from environment. Hypervariable V1–V9 regions of the 16S ribosomal RNA gene are used to identify bacterial communities; whereas, 18S rRNA genes are used to identify fungal communities by next generation sequencing. Bacterial artificial chromosomes (BAC), cosmid, and fosmid are used as a vector and E. coli as a host for cloning of DNA fragment to construct metagenomic library. Sanger sequence-based screening approaches are used to identify microbial enzymes from metagenomic library of environmental samples

Fig. 2

Schematic representation of biogas and biofuels production from the lignocellulosic biomass, oil crops, sugarcane/food waste through pre-treatment, and anaerobic digestion. Sugar, fat, and proteins are converted into organic acids and alcohols by acidogenesis; organic acids and alcohols are converted into hydrogen (H₂), carbon dioxide (CO₂), and acetic acid (CH₃COOH) by acetogenic bacteria. Methanogenic bacteria are involved in the synthesis of biogas from CH₃COOH, CO₂, and H₂