Journal Club: Microbial Biosynthesis of Alkanes

I recently read an article titled “Microbial Biosynthesis of Alkanes” that appeared Science (Vol. 329, 559, 2010) was published by Andreas Schirmer et. al. By comparing nine cyanobacteria known to produce hydrocarbons (alkanes, and alkenes) to one species known not to produce any hydrocarbons, genes that exist only exist in the 9 other species. The genes that were identified this way became likely candidates for the alkane biosynthesis pathway. Two classes of proteins were identified: short-chain dehydrogenases or reductases, and the ferritin-like or ribonucleotide reductase-like proteins. Previously, it was predicted that alkane biosynthesis happens by decarbonylation of fatty aldehydes. The authors speculated that the dehydrogenase-like gene could encode a protein that initiates the reduction of a fatty acid intermediate while the ribonucleotide reductase-like protein could complete the decarbonylation reaction. The authors noted that the gene pair classes described above often occurred next to each other and therefore likely form an operon which are genes that are expressed together at the same time. To test the above hypothesis, the authors expressed operones described above in E. coli which is known not to produce alkanes. Putting these two genes into E. coli enabled the organism to now produce alkanes and alkenes.

The take-home message: Gasoline and other fossil-based fuels to a large part consist of alkanes and alkenes. Although researchers were speculating about how these hydrocarbons could be produced in living organisms, this paper for the first time clearly identifies two protein classes that can actually synthesize the reaction which could form the basis for a bio-based way of fungible (directly usable) biofuels.

I encourage everyone to read this from source directly here:

http://www.sciencemag.org/cgi/content/short/329/5991/559

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