Fig 1. Gaps in amino acid biosynthesis in 10 bacteria.

For each amino acid, we identified the missing reactions or gaps in the IMG predictions, and we show a single-letter code with the classification of each gap. A cell may have multiple codes, one for each gap. “Clear candidate” means that at least two annotation resources identified a gene for the gap. If there was more than one gap with a clear candidate, this is shown with a number (i.e., “c2” for two gaps with clear candidates). “Known” means that the step is described in the literature but not in the databases. Some reactions are involved in the biosynthesis of multiple amino acids, so some gaps are shown multiple times.