Phosphate uptake in an obligately marine fungus. II. Role of culture conditions, energy sources, and inhibitors

Phosphate uptake in the obligately marine fungus, Thraustochytrium roseum, is maximal at pH 7.5 to 7.8, is dependent on temperature, and varies with phosphate concentration. Pyruvate and succinate stimulate phosphate uptake, although they do not increase respiration. The uncoupling agents, 2,4-dinitrophenol and dicoumerol, inhibit phosphate uptake but stimulate oxygen consumption only in the presence of NaCl. Oligomycin inhibits both processes. Among the inhibitors of protein synthesis, chloramphenicol reduces phosphate uptake without affecting respiration. Puromycin is unique in that it greatly enhances phosphate uptake and abolished the lag period associated with this phenomenon. It does not affect respiration.