Carotenoid Pigments in a Mutant Strain of Verticillium albo-atrum Reinke and Berthold

Abstract

THE only pigment known to be produced by wild-type strains of V. albo-atrum is of a dark melanoid type¹. In an investigation involving the production of biochemical mutants in this fungus (using a strain originally isolated from wilted lucerne, 1962), an orange pigmented colony, which had a partial requirement for biotin, developed on plates of complete medium spread with conidia irradiated with ultra-violet at a dosage allowing for approximately 5 per cent survival. The irradiation was carried out using a sterile distilled water suspension of conidia in an open Petri dish at a distance of 20 cm from a 2537 Å ‘Hanovia’ bactericidal tube model 11 (with ozone reducing filter). The close resemblance of this colony (designated M.5) in morphological details to wild-type led us to conclude that it is a mutant rather than a chance contaminant. The results of a preliminary extraction of M.5 suggested that several different carotenoids were present, and from further work, reported here, we have been able to identify some of these pigments.