Figure 2.

Enzymes involved in anaerobic hydrocarbon degradation and the corresponding genes detected in the metagenomes of NAPDC, SCADC and TOLDC. (a) Known pathways (substrates) for anaerobic hydrocarbon metabolism and associated enzymes. (b) Heatmap showing the presence of various genes and putative genes involved in anaerobic hydrocarbon metabolism in the metagenomes. The color scale indicates the inferred enzyme completeness, in the case of enzymes with multiple subunits. Enzyme abbreviations: EbdABC, ethylbenzene dehydrogenase; Ped, (S)-1-phenylethanol dehydrogenase; Apc1 to Apc5, acetophenone carboxylase; Bal, benzoylacetate-CoA ligase; BssABC, benzylsuccinate synthase trimer; BbsEF, succinyl-CoA:(R)-benzylsuccinate CoA transferase; BbsG, (R)-benzylsuccinyl-CoA dehydrogenase; BbsH, phenylitaconyl-CoA hydratase; BbsCD, 2-[hydroxyl(phenyl)methyl]- succinyl-CoA dehydrogenase; BbsAB, benzoylsuccinyl-CoA thiolase; AbcDA, anaerobic benzene carboxylase; BzlA/BamY, benzoate-CoA ligase; BcrABCD, benzoyl-CoA reductase (ATP-dependent); BamB to BamI, benzoyl-CoA reductase (ATP-independent); NmsABC, naphthyl-2-methyl-succinate synthase; BnsEF, naphthyl-2-methyl-succinate CoA transferase; BnsG, naphthyl-2-methyl-succinate dehydrogenase; BnsH, naphthyl-2-methylene-succinyl CoA hydratase; BnsCD, naphthyl-2-hydroxymethyl-succinyl CoA dehydrogenase; BnsAB, naphthyl-2-oxomethyl-succinyl CoA thiolase; AncA, anaerobic naphthalene carboxylase; NcrABC, 2-naphthoyl CoA reductase; AssABC, alkylsuccinate synthase; AssK, AMP-dependent synthetase and ligase; Mcm, methylmalonyl CoA mutase; Mcd, methylmalonyl-CoA decarboxylase. Based on the models used, Mcd and benzoyl-CoA thiolase were abundant in all metagenomes. It was not known whether any of the genes identified were associated with hydrocarbon-degrading pathways or more general decarboxylase and thiolase functions, thus they have been omitted from the heatmap to curtail over-interpretation of the data.