Specificity of Pigment Formation by Penicillium rubrum Stoll

THOUGH Penicillium rubrum Stoll can often be isolated from mould growth on organic substance and is, indeed, very widely distributed, the appearance of the red pigment at the site of the growth, which is one of its important characteristics, is not at all frequent. This fact suggests that some strict specificity exists in pigment formation by P. rubrum . During a preliminary study 1 on pigment formation by P. rubrum Stoll, interest was aroused by the fact that while a number of hexoses and pentoses, providing a source of carbon, gave good pigment formation, a few of them invariably failed to produce the pigment, although they served the nutritional requirements of the mould equally well. Experimental evidence indicates that the source and quantity of nitrogen, within wide limits, had no effect on pigment formation nor was it dependent on the presence of trace elements. That pigment formation was closely connected to some specificity of the saccharide molecules used as the carbon source in the culture was evident from such observations.