Converting Fatty Acids to Alkanes with Blue Light

The production of fatty-acid derived fuels and chemicals by microbial metabolism offers a renewable alternative to petroleum-based fuels on the market. Microbial hydrocarbon biosynthesis in particular is a target for metabolic engineering efforts due the potential use of alkanes and alkenes as drop-in transportation fuels. Here, we explore the development of an Escherichia coli strain engineered for increased fatty acid production and conversion of fatty acids to alkanes by a light-driven enzyme. This photoenzyme, named fatty acid photodecarboxylase (FAP), is native to microalgae Chlorella variabilis and has been shown to directly decarboxylate fatty acids to their corresponding C_n-1 alkanes in a reaction catalyzed by blue light. By deleting the fadD and fadE genes responsible for fatty acid degradation and expressing FadR and ‘TesA proteins for increased free fatty acids, we were able to show increased alkane production by the FAP enzyme in vivo. Our findings suggest that the FAP enzyme could be useful for the production of biodiesel-like alkanes and further investigation into other light-regulated metabolic pathways is warranted.