The Oxidation of Lard Oil by Penicillium chrysogenum

SUMMARY: Under the conditions prevailing during the early stages of certain highly aerated penicillin fermentations, lard oil and oleic acid appear to be oxidized only slowly, or not at all, by suspensions of washed mycelium of Penicillium chrysogenum. Lard oil and oleic acid are both oxidized rapidly, however, under the conditions present at 48 hr. and after. The optimum pH for oxidation of lard oil by suspensions of washed mycelium c. 48 hr. old is 8·1 and for oleic acid, c. 6·4, but oxidation of both lard oil and oleic acid was apparent at the pH prevailing during the early stages of the fermentation (5·5–6·0).

Mycelium from shaken flask fermentations (conditions of relatively low aeration) appeared to oxidize lard oil only slowly even during the later stages of the fermentation although oleic acid, which is the principal product of hydrolysis of lard oil, was oxidized rapidly.

The results suggest that enzymes involved in the oxidation of lard oil and oleic acid may be present only in relatively low concentration in young mycelium and be synthesized as growth takes place. The ability to oxidize lard oil also appears to be favoured by conditions of high aeration during growth.