Differentiation of Serratia marcescens and Serratia liquefaciens by tests for lipase and phospholipase production.

The production of lipase and phospolipase by certain members of the Enterobacteriaceae was examined by thin-layer chromatography of resting-cell suspensions incubated with triolein or lecithin. Most strains of Serratia marcescens produced both enzymes while most strains of Serratia liquefaciens exhibited strong lipase but only a minor phospholipase activity. Enterobacter spp. (25 strains), Klebsiella pneumoniae (20 strains), Escherichia coli (15 strains), Citrobacter freundii (7 strains) and Proteus spp. (20 strains) lacked both types of enzymic activity except for the following: three strains of Enterobacter cloacae, two of Proteus mirabilis and three of Proteus vulgaris possessed slight lipase activity; about one-half of the Enterobacter aerogenes and Enterobacter hafniae strains examined produced slight phospholipase activity. It is suggested that tests for lipase and phospholipase should be used in conjunction with those for DNAase production and sugar fermentation for the differentiation of S. marcescens and S. liquefaciens.