Phospholipid as a growth factor of Uroglena americana, a red tide Chrysophyceae in Lake Biwa.

Abstract

To determine the bacterial factor necessary for the growth of Uroglena americana, a red tide Chrysophyceae in Lake Biwa, various extracts from cells of Escherichia coli were added to a temporary axenic culture of U. americana and effect on the algal growth was examined. Water extract of bacterial cells was ineffective to promote grwoth of U. americana, but chloroform/methanol extract supported good growth. After fractionation and purification of the extract, it was revealed that the active compound contained in the bacterial cells was phosphatidyl ethanolamine. Addition of highly purified commercial phosphatidyl ethanolamine resulted in an excellent growth of U. americana. This requirement was also fulfilled by the high purity natural phospholipids, indicating no specific requirement for phospholipids in U. americana. Phosphatidic acid supported good growth of U. americana but glycerophosphate (a precursor of phosphatidic acid) did not. Several glycerides and free fatty acids were not as nutritionally effective as phospholipids.