LIPIDS OF SERRATIA MARCESCENS

Abstract

Cells of Serratia marcescens, whether pigmented or unpigmented, contained 10–11% of methanol–chloroform extractable lipids (dry weight basis) and < 1% of bound lipids. The extractable lipids contained 34–43% phosphatides, 3–11% unsaponifiable material, and 2–5% free fatty acid. The phosphatides contained high proportions of phosphatidyl ethanolamine and smaller amounts of phosphatidyl serine, polyglycerol phosphatides, phosphatidyl glycerol, and an unidentified ninhydrin-positive phosphatide probably associated with ornithine and other amino acids found in the lipid hydrolyzate.The fatty acids were found to consist largely of palmitic, C17- and C19-cyclopropane and C16- and C18-monoenoic acids. The proportions of monoenoic and cyclopropane acids were found to vary greatly with the age of the cultures; in the early stages of growth, regardless of pigmentation, low amounts of cyclopropane acids and high amounts of monoenoic acid were present, the latter being converted almost completely to cyclopropane acids during the active growth phase.The lipids associated with extracellular lipopolysaccharide material were similar in composition to the cellular lipids.