A substance causing abnormal development of fungal hyphae produced by Penicillium janczewskii zal. : I. Biological assay, production and isolation of ‘curling factor’

Abstract

Strains of Penicillium Janczewskii Zal. are shown to produce a substance, when grown on synthetic liquid culture media, which causes an unusual stunting and distortion of the germ-tubes and hyphae of Botrytis Allii and other fungi. This substance, known as ‘curling factor’, is produced more abundantly in media containing nitrogen as nitrate than in media containing nitrogen as ammonium salts or peptone. The optimum concentration of glucose in the media is 7·5%, which is noticeably better than 5·0%. Increase in glucose concentration to 10·0% or higher gives no further advantage. The ‘curling factor’ may be removed from active culture-filtrates by extraction with chloroform, ether or n -butyl alcohol or by treatment with activated charcoal followed by elution of the charcoal with ether or chloroform. By extraction with chloroform followed by successive crystallization from ethyl alcohol and dioxan/water mixtures, ‘curling factor’ has been obtained in pure form as colourless crystals. Yields of 150 mg./l. of culture filtrate can be obtained. In concentrations of 25μg./ml., ‘curling factor’ causes the production of short stunted germ-tubes by Botrytis Allii , whose development ceases at an early stage ; lower concentrations (1·0 μg./ml.) cause excessive branching and distortion and lower concentrations still (0·2 μg./ml.) cause a waving of the hyphae. It is characteristic of the substance that relatively high concentrations (100 μg./ml.) do not prevent germination of B. Allii conidia, though far lower concentrations cause the profound physiological effects described.