Association of 6-oxo-piperidine-2-carboxylic acid with penicillin V production in Penicillium chrysogenum fermentations.

Analysis of a 13C NMR spectrum of a concentrated broth from Penicillium chrysogenum fermentation revealed the presence of penicillin V and 6-oxo-piperidine-2-carboxylic acid(1) as the principal constituents. The latter lactam, identical to an authentic sample prepared by the cyclization of alpha-aminoadipic acid was present to the extent of 28 mol% of penicillin V. The lactam isolated form the broth was nearly racemic, having a slight excess of the L-isomer. This isolation provides further evidence regarding the biosynthetic precursors of the hydrophobic penicillins.