Bio-prospecting for naturally occurring enzymes, involved in decay and digestion, is an appealing strategy to find better ways to convert woody and recalcitrant biomass into biofuel. Work just published in Biotechnology for Biofuels, by Luen-Luen Li and colleagues, takes a meta-genomics approach to this search. High-throughput sequencing of microbial decay communities in poplar biomass identified 4,000 glycoside hydrolase (GHase) type enzymes. From a sub-set that were selected for characterization, four novel enzymes were found that have potential biofuels application.
The plummeting cost of genome sampling means that the latter approach is increasingly profitable in terms of technical investment. A more targeted study, on a candidate species level, was reported by King et al. (2011) who assayed the plant cell wall degrading activity of a collection of 256 known plant fungi.
The animal kingdom is not ignored in its ability to host cellulose digestion. Our Associate Editor for Biotechnology for Biofuels, Ed Bayer, leads research into bacterial cellulosomes (multi-enzyme complexes) including those found in the stomach of ruminants (e.g. Alber et al. 2009). The digestive mechanism of termites has also been investigated and an analysis of host and symbiont gene expression in the termite gut, published by Tartar et al. (2009) has been cited an impressive 22 times (source: Scopus).
Li LL, Taghavi S, McCorkle SM, Zhang YB, Blewitt MG, Brunecky R, Adney WS, Himmel ME, Brumm P, Drinkwater C, Mead DA, Tringe SG, van der Lelie D.(2011) Bioprospecting metagenomics of decaying wood: mining for new glycoside hydrolases. Biotechnol Biofuels.4:23.
King BC, Waxman KD, Nenni NV, Walker LP, Bergstrom GC, Gibson DM. (2011) Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi. Biotechnol Biofuels.16:4.
Alber O, Noach I, Rincon MT, Flint HJ, Shimon LJ, Lamed R, Frolow F, Bayer EA. (2009) Cohesin diversity revealed by the crystal structure of the anchoring cohesin from Ruminococcus flavefaciens. Proteins.77(3):699-709.
Tartar A, Wheeler MM, Zhou X, Coy MR, Boucias DG, Scharf ME. (2009) Parallel metatranscriptome analyses of host and symbiont gene expression in the gut of the termite Reticulitermes flavipes. Biotechnol Biofuels.15:25.
Photo by Althepal (Wikimedia Commons).