Functional characterization of metagenomes. A) Three published environmental sequence datasets have been searched for instances of the RuBisCo and RuBisCo-like enzyme families, using MLTreeMap. Colored spheres represent sequences mapping to a specific position in the tree, whereby the area of each sphere indicates the relative amount of sequences. The resulting placements are largely non-overlapping, suggesting distinct functional RuBisCo classes encountered/required at each of the environmental sites. B) Several datasets, as available at  and , were assessed with respect to two metabolic functions (CO2 fixation, and nitrogen fixation, respectively). All counts were normalized with respect to sampling depth, and are thus directly comparable.
Stark et al. BMC Genomics 2010 11:461 doi:10.1186/1471-2164-11-461