6-Aminopenicillanic acid I. 6-Aminopenicillanic acid in penicillin fermentations

Abstract

When a side-chain precursor was omitted from a penicillin fermentation, the yield of penicillin was diminished and 6-aminopenicillanic acid accumulated. In general, the conditions for 6-aminopenicillanic acid formation were similar to those for penicillin formation. Different requirements existed, however, with respect to aeration and the presence of precursor. During the growth phase, a high aeration rate favoured the formation of both the penicillin and 6-aminopenicillanic acid-producing systems. During the production phase, an oxygen transfer rate permitting the maximum respiration was required for maximum rate of penicillin formation. 6-Aminopenicillanic acid formation, on the other hand, was depressed under such conditions of aeration and the maximum rate of 6-aminopenicillanic acid formation by washed mycelium occurred with an oxygen transfer rate which limited respiration to approximately 60 % of maximum. A high aeration rate was necessary for efficient utilization of precursor for penicillin formation and under such conditions, the presence of precursor resulted in an increase in the total amount of penicillin nucleus produced in the fermentation.