Nature’s bioreactor: the rumen as a model for biofuel production

Abstract

As a major component of the plant cell wall, cellulose is the most abundant source of terrestrial carbon and therefore attractive for biofuel production. However, current industrial efforts to convert plant biomass into biofuels have been hampered because plant polysaccharides such as cellulose and hemicelluloses are difficult to break down and the fermentation of the resulting sugars is not efficient. Natural systems that hydrolyze and ferment cellulose could therefore inform these industrial efforts. The rumen, as part of the digestive tract in some herbivores, houses a microbial community that naturally and efficiently hydrolyzes cellulose and ferments the resulting sugars to products that are precursors to biofuels. Genomic and metagenomic sequencing of the rumen microbial community is leading to the discovery of fibrolytic enzymes and the identification of the multiple approaches used by rumen microbes to digest cellulosic substrates. These sequencing efforts are also identifying microbial interactions that make the rumen one of the most efficient bioreactors on Earth.

Acknowledgements

The authors would like to thank all members of the G Suen laboratory for their critical reading of this review.

Financial & competing interests disclosure

This work was supported by DOE BER Early Career Research Program Award DE-SC0008104 and funding from the Wisconsin Bioenergy Initiative to G Suen. MR Christopherson was supported by a joint Post-Doctoral Research Fellowship from the DOE Great Lakes Bioenergy Research Center (DE-FC02-07ER64494) and a DOE BACTER training grant (DE-FG2-04ER25627). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.