Challenges of Synthetic Biology and Metabolic Engineering in New Biofuel Production Technologies

The role of metabolic engineering and synthetic biology as enabling technologies for the production of alcohol biofuels (i.e. ethanol and butanol) was reviewed by Ramon Gonzalez of Rice University (United States) and colleagues. Advances in synthetic biology, metabolic engineering, and systems biology have resulted in the harnessing of biofuel-producing microorganisms for new pathways of redirecting carbon metabolism into desired products.

Some of the new pathways that were reviewed are: (1) expression of pentose catabolic pathways in conventional ethanol-fermenting strains of Saccharomyces cerevisiae and Zymomonas mobilis (wild strains do not usually have the capability to metabolize pentoses, only hexoses) ,(2) conversion of sugars from lignocellulosic biomass to butanol (butanol is considered an ‘advanced biofuel" with better fuel properties than ethanol), (3) sugar conversion to advanced biofuel (particularly those that are similar to gasoline hydrocarbons). (4) efficient co-metabolism of sugar mixtures (i.e. simultaneous, not sequential utilization of sugar mixtures in saccharified/pretreated biomass), and (5) conversion of glycerol-rich feedstocks to biofuels (glycerol is a by-product in biodiesel production).

In the review, the authors found "recurring themes" related to (1) strategies for heterologous gene expression, (2) evolutionary selection, and (3) "reverse" metabolic engineering. Advances in the "-omics" sciences have also increased new knowledge "by probing cellular changes associated with new phenotypes and driving the construction of efficient microorganisms for biofuels production." The full review is published in the journal, Microbial Cell Factories (URL above).