Some Chemical Factors Influencing Growth and Pigmentation of Certain Microörganisms

Abstract

Large concns. of biologically important catalytic metals (Mn++, Cu++, Fe+++) inhibit growth of microorganisms; smaller concns. lead in some cases to loss of pigmentation. Where the organisms are very sensitive to Cu or when pigmentation is inhibited by it, the toxic effect of the metal may be counteracted by liver extracts. The binding effect of metals by liver extracts leads in the case of organisms which require metals, particularly Fe, for their growth, to inhibition of growth by liver extract. Sarcina lutea is the most striking example of the type of organisms where growth is inhibited by liver extracts. The development of pigment in cultures of Serratia marcescens does not specifically require glucose in the medium but depends upon the presence in it of substances which contain available aldehyde or ketonic groups. Pigment formation in Staphylococcus aureus, Pseudomona pyocyanea, Serratia marcescens, Torula rosea, Sarcina lutea, Spirillum rubrum and Aspergillus niger, when grown in different media, could be inhibited by diphenylamine. In some instances the loss of pigment could be attained on the medium containing the diphenylamine on the first transplant. while others required several subculturings.