Enantiomer discrimination in β-phenylalanine degradation by a newly isolated Paraburkholderia strain BS115 and type strain PsJN

Despite their key role in numerous natural compounds, β-amino acids have rarely been studied as substrates for microbial degradation. Fermentation of the newly isolated Paraburkholderia strain BS115 and the type strain P. phytofirmans PsJN with β-phenylalanine (β-PA) as sole nitrogen source revealed (S)-selective transamination of β-PA to the corresponding β-keto acid by both strains, accompanied by substantial formation of acetophenone (AP) from spontaneous decarboxylation of the emerging β-keto acid. While the PsJN culture became stationary after entire (S)-β-PA consumption, BS115 showed further growth at a considerably slower rate, consuming (R)-β-PA without generation of AP which points to a different degradation mechanism for this enantiomer. This is the first report on degradation of both enantiomers of any β-amino acid by one single bacterial strain.