The effect of nutrients on formation of penicillin by washed mycelium of Penicillium chrysogenum.

Many different substances are known to affect the yields of penicillin from growing cultures of Penicillium chrysogenum. Under the usual conditions, it is difficult to distinguish between the effect of a substance on growth of the mould (and hence the indirect effect on production of penicillin) and its direct effect on antibiotic synthesis. The use of washed mycelium (Halliday & Arnstein, 1956) was considered as a solution to the problem, since such mycelium can produce penicillin in a simple medium which would not permit growth. Washed mycelium is known to require oxygen and phenylacetate to synthesize benzylpenicillin. The amino acids cystine and valine are incorporated if they are added, as can be shown by radioactive-tracer experiments (Halliday & Arnstein, 1956), but their effect on yields of penicillin from washed mycelium has not been examined critically. This report summarizes experiments which show that several amino acids and other nutrients cause significant changes in the yield of penicillin.