Fig. 4

Putative degradation mechanisms of (R)-β-PA. In blue: putative degradation mechanisms of (R)-β-PA. Since AP no longer emerges when (R)-β-PA is consumed but rather decreases during fermentation (see again Additional file 1: Figure S1a), the reactions via aminomutase appear to be more likely. Bacterial ammonia lyases (dashed arrow) with activity towards β-PA have not yet been reported. In black: identified degradation pathways of (S)-β-PA. The degradation of (S)-β-PA occurs via transamination and leads to the formation of AP reciprocal to (S)-β-PA decline (as shown in Additional file 1: Figure S1a)