Fig. 5

Representative metabolic maps of bacterial groups in the bioreactor. To prevent redundancy, the metabolism is presented in a nested approach with each panel showing only paths unique to the relevant metabolic group. Two exceptions are Group β (all detected paths are shown), and Group δ. The latter is not presented here since it shares all paths with Group ɣ and only differs by auxotrophies. (A) Metabolic map of paths that are common to all bacteria in the bioreactor (except Microgenomates and Brocadia sp.). The vast majority of bacteria in the bioreactor are heterotrophs, capable of carbohydrate-based metabolism (glycolysis, pentose phosphate pathway), and amino acid-based metabolism. Some bacteria can respire oxygen and can also ferment (acetate/alanine). (B) Paths unique to Group ɑ. These bacteria have genes for hydrogen oxidation, supporting anaerobic growth, as well as genes for oxidative phosphorylation with cytochrome BD complex. These bacteria have a cassette of extracellular proteases and decarboxylases, paired with a wide array of transporters. They are also potentially capable of synthesizing long chain isoprenoids. (C) Paths found in Gram (–) bacteria (Groups ɣ, δ, and ε). Most paths are related to fatty acid and lipid synthesis. Several important precursors (chorismate and IMP) can potentially be synthesized by these bacteria. Motility is also a common feature in these bacteria (via a flagellar motor). (D) Unique paths of Group ε (Proteobacteria). This group has the potential to synthesize multiple vitamins and cofactors (biotin, pyridoxal, glutathione, etc.), as well as several amino acids (tyrosine, phenylalanine, proline). Another unique feature is the multiple secretion systems present in the bacteria. (E) Metabolic profile of CPR bacteria (Microgenomates). These bacteria are obligate anaerobes that ferment pyruvate. They can only utilize carbohydrates as their carbon source. Some of the bacteria in this group might also be able to synthesize long chain isoprenoids, in the same path as Group ɑ