Studies in the Physiology of the Fungi. XV. Germination of the Spores of Certain Fungi in Relation to Hydrogen-Ion Concentration

Abstract

The effect of the hydrogenand the hydroxyl-ion concentration in a mannite medium upon germination of the spores of certain fungi, Aspergillus niger, Penicillium cyclopium, Botrytis cinerea, Fusarium sp., and Lenzites saepiaria, and the range within which their most favorable germination occurs have been presented in a recent paper (Webb, '19). Very striking data were obtained from this preliminary study, the features of particular interest being (1) the importance of active acidity in germination and (2) the relatively low percentage of germination under conditions of active alkalinity. It was found, in general, that the majority of the fungi employed showed maximum germination of the spores with relatively high acidity, namely, PH 3.1, and further, that none of the fungi suffered inhibition of germination on the acid side of neutrality until a hydrogen-ion concentration greater than that of PH 2.8 was passed. Germination quantities in most cases decreased, though not necessarily proportionally, with decrease in hydrogen-ion concentration from the optimum concentration previously mentioned. Certain forms, however, such as Penicillhum cyclopium and Fusarium sp., exhibited secondary maxima at or near neutrality. The medium employed in that investigation contained mannite as the sole nutrient, and its hydrogenand hydroxyl-ion concentrations were adjusted by means of equal additions of orthophosphoric acid and successively increasing additions of sodium hydroxide. Logical questions which naturally arise at this