Microbiology of saturated salt solutions and other harsh environments: v. Relation of inosine-5'-phosphate and carbohydrate to growth of wildtype and mutant penicillium in boric Acid and potassium chloride selective media.

The study of chemical stress tolerance in a Penicillium mutant was continued using KCl- and H(3) BO(3) -saturated glucose peptone broth as a basic growth medium. Growth was completely restricted to the mutant. Variations were the presence or absence of inosine-5'-phosphate (inosinic acid, IMP) and choice of carhohydrate which was substituted for glucose. All six monosaccharides used-three hexoses, three pentoses - were essentially equivalent hence data are presented only for D-glucose and D-xylose. The other carbohydrates, sucrose, lactose, maltose and starch differed in their suitability as carbon sources. In the presence of the nionosaccharides the mutant can grow both in KCl and H(3) BO(3) media, but growth rates are greatly enhanced by IMP. Boric acid blocked sporulation under all conditions. KCl permitted spores of abnormal color to form without IMP, whereas spores of normal green color appeared in its presence. Media containing H(3) BO(3) and disaccharides or starch supported no growth, but addition of IMP stimulated growth without sporulation. In KCl media sucrose alone among the disaccharides and starch permit limited growth without IMP, but the nucleotide is required for sporogenesis. These results show that the role of nucleotides, especially IMP, is not limited to recovery from exposure to extreme salt effects, but also applies to growth in the continuing presence of quite different chemical stress conditions.