Pigment Formation by Penicillium rubrum Stoll

Abstract

DURING an investigation on the appearance of red-pigmented patches on chrome-tanned hide it is found that this pigmentation is caused by the growth of Penicillium rubrum Stoll on it. Though such pigmentation is a common phenomenon, its occurrence is not frequent. Penicillium rubrum Stoll, like other members of Penicillium purpurogenum series, represents almost a common mycoflora of soil and other organic matter and produces red pigmentation on the substrate on which it grows. Therefore, the rarity of occurrence of such pigmentation on chrome-tanned hide and, in fact, on other organic matters is surprising and obviously suggests some strict specificity involved in pigment formation by Penicillium rubrum Stoll. Some of these specificities have been determined on laboratory culture media. Sabouraud's medium with 1.0 per cent ‘Bactopeptone’ (Difco), 4.0 per cent glucose A.R. (B.D.H.), 2.5 per cent agar, pH 5.0–5.5, is taken as the basal medium on which Penicillium rubrum Stoll produces intense red pigmentation in 4–8 days at 23°–25°. Substitution of one or the other constituent of the medium was made for specific studies. Abbreviations used for visual assessment of the formation of pigment are P− = pigment nil; P+ = pigment positive; each additional plus (+) sign indicates proportional increase in intensity of the pigment.