A study of the environmental conditions needed for maximal laboratory yields of pulvilloric acid, an antibiotic substance produced by Penicillium pulvillorum, led to the estimated production in stationary cultures of quantities over 1.3 g/1. The requisite medium is 5% glycerol-Czapek-Dox supplemented with 0.1 ml of corn steep liquor/1. Improvements in isolation and purification steps were found which overcame the major difficulty involved in work with this metabolite, i.e., its instability. A complete stepwise degradation procedure, adaptable for radioactive tracer experiments, was developed. This process involved hydrolysis of pulvilloric acid into the known l-(3-dihydroxyphenyl)-2-heptanol, followed by methylation and dehydration which provided l-(3,5dimethoxyphenyl)-1 -heptene. The latter intermediate was p X. ulvilloric acid is a yellow antifungal and antibacterial substance produced by Penicillium pulvillorum (Brian et al., 1957). Its molecular structure (I) has been determined by degradative (McOmie et al., 1963(McOmie et al., , 1966 and synthetic (Bullimore et al., 1967) studies. Both in biogenetic and structural terms, pulvilloric acid closely resembles two other secondary metabolites. These are citrinin, whose biogenesis has been worked out by several groups (Birch et al., 1958;Schwenk et al., 1958;Rodig et al., 1966) and has been shown to involve the acetate-polymalonate single carbon-transfer pathways; and ascochitine, more recently characterized by Iwai and Mishima(1965).This paper reports strain and fermentation improvements which have lead to consistent, high yield production of pulvilloric acid; and describes a facile isolation method for obtaining the analytically pure antibiotic. As a preliminary to radioactive tracer experiments on the elucidation of the biosynthesis of pulvilloric acid, a carbon-by-carbon degradative procedure, with satisfactory yields of intermediates at each stage, has been developed.
Experimental Procedures and ResultsFermentations. It was earlier reported (Nakajima and Tanenbaum, 1968) that strain selection by sectoring of P.pulvillorum (ACC 1124) as originally received, led to isolates
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