Mineral nutrition of Pythium marinum, a marine facultative parasite

Abstract

Pythium marinum Sparrow, isolated from lesions on Porphyra miniata, required Na+, Ca2+, and Mg2+ in quantities far exceeding those reported to be required by terrestrial species of Pythium. Unlike most of its terrestrial counterparts, P. marinum required alkaline pH values for good growth, with a pH of 7.8 providing maximum growth under the conditions examined. The requirement for large amounts of Na+ ions appeared to have a specific nutritional basis rather than a purely osmotic function. Growth at various temperatures indicated that the fungus is a facultative psychrophile with the optimum growth temperature between 15 and 20 °C. The nutritional data show that P. marinum is able to grow in a wide range of salt concentrations and is well adapted to the marine environment.