Fig. 5: Widespread fermentation pathways and molecular hydrogen production in chlamydiae.

a Representation of putative anaerobic pathways for ATP generation and molecular hydrogen metabolism in chlamydiae. Labels next to enzymatic reactions indicate the associated enzymes. Numbers in squares correspond to phylogenetic trees in (c). Colors indicate affiliation with different pathways—pyruvate fermentation (yellow), ADI pathway (violet), hydrogen metabolism (orange). b Species tree of chlamydial representative genomes as in Fig. 3 collapsed at the family rank. Branch support values are based on 100 non-parametric bootstraps, support ≥ 70% is indicated as black circles. Box next to family names indicates the number of non-redundant genomes in a family with the respective color coded metabolic pathway. Pyruvate fermentation to acetate was only counted if genes encoding the complete pathway were present, i.e., pyruvate dehydrogenase complex (PDC), or pyruvate ferredoxin oxidoreductase (PFO) together with phosphate acetyltransferase (Atp) and acetate kinase (AckA), or acetate-CoA ligase (Acs). Likewise, arginine deaminase (ADI) pathway was only counted if genes encoding arginine deaminase (ADI), ornithine carbamoyltransferase (OTC), and carbamate kinase (CK) were present in a genome. c Unrooted maximum likelihood phylogenetic trees with best fit models numbered and colored according to (a) with 1000 optimized ultrafast bootstrap and 1000 SH-like approximate likelihood ratio test support. Best fit models per gene are indicated under the gene name and clades are named by family.