The Influence of Carbon and Nitrogen Nutrition on Growth and Sterolinduced Sexuality of Pythium SP. PRL 2142

SUMMARYThe influence of the major constituents of a chemically defined nutritional medium on growth and sexuality of Pythium sp. PRL 2142 has been determined. Addition of cholesterol to the culture medium stimulated vegetative growth and the response to sterol was quantitative up to a maximum concentration of 60 mg of sterol per liter. The number of oospores produced was proportional to the concentration of sterol within limits determined by the carbon and nitrogen source. Glucose, fructose, maltose and cellobiose were suitable carbon sources for both growth and oospore production whilst alanine, arginine and asparagine proved suitable nitrogen sources. A carbon/nitrogen ratio in the range 15 to 30:1 was optimal for both growth and the production of oospores. Oospore production with asparagine as nitrogen source was at least three times greater than when alanine or arginine was supplied.