초록
<P><B>Abstract</B></P> <P>Increasing global energy demand and environmental concerns associated with petroleum have raised interest in biofuels for reducing dependency on crude oil and promote carbon-neutral energy generation. Although ethanol is a well-established biofuel, properties like low energy density, hygroscopicity and corrosiveness limit their usage in existing transportation sectors. Need for more energy‐dense fuel similar to conventional oil has motivated research on advanced biofuels like butanol, isobutanol, fatty-acid and isoprenoid-derivatives. These fuels not only have very similar energy content and combustion properties to existing fuels but also their storage and transportation properties are compatible with the current infrastructure. Microbes have the native pathway for the synthesis of these molecules, but natural titer is significantly low for commercialization. Metabolic engineering approaches can help in redirecting the cellular fluxes towards these pathways thus improving the titer for microbial synthesis of advanced biofuels. This review provides a comprehensive outlook on the trends and developments in metabolic engineering strategies for advanced biofuel production using different hosts. Possible strategies include protein engineering, co-factor balancing using rapid genome engineering tools like CRISPR/Cas9, MAGE/eMAGE, RNAi. Additionally, <I>in silico</I> approaches like flux balance analysis and <SUP>13</SUP>C metabolic flux analysis can help in the further improvisation and optimization of designed pathways to maximize carbon-flux towards desired pathways. However, the techno-economic analysis predicts that commercialization of biofuels is highly influenced by feedstock and productivity. Still, several countries have adopted energy mandates to incorporate these fuels in transportation sector for a greener and cost-effective energy supply. An integrated approach involving metabolic engineering and systems biology would help in improving titer of advanced biofuels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Beneficial properties of advanced biofuels comparable to fossil fuel are mentioned. </LI> <LI> Metabolic engineering strategies in rewiring cellular machinery are discussed. </LI> <LI> CRISPR/Cas9 aided genome engineering for microbial biofuel production is provided. </LI> <LI> <I>In silico</I> approaches for pathway optimization towards bioproduction is studied. </LI> <LI> Techno-economic state and policies for biofuel commercialization is analyzed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>