Studies of a New Species of Thraustochytrium that Displays Light Stimulated Growth

SUMMARY

The development of Thraustochytrium roseum, a new pigmented marine Phycomycete, is described from its growth on pollen in sea water. Morphological variations produced on nutrient media under diverse conditions are detailed. When cultivated in shake culture, light accelerated the logarithmic growth phase of the fungus. This unusual result can not be ascribed to a temperature difference of less than 1 C between experimental flasks. Both light and dark grown thalli become pigmented. Temperatures of 15–30 C favored maximal harvests as did NaCl concentrations of 1.5-4.0%. The replacement of this salt by KCl or CaCl₂ does not permit the growth of this obligately marine form. Although inorganic nitrogen as (NH₄)₂SO₄ can serve as a sole source of that element, markedly better yields are secured with glutamate, asparate, their amides, and with alpha alanine. Carbon assimilation surveys revealed that T. roseum thrives with glucose, maltose, soluble starch or cellobiose.