摘要：The identification method for Legionella species which was difficult to be identified with biochemical test was investigated by Comparing cellular fatty acid composition. First, a simple and rapid analytical method for the determination of cellular fatty acids of Legionella species by gas chromatography (GC) was developed. Cell cluster (about 50 mg) in 1 ml of 2 N sodium hydroxide-methanol solution was heated at 70°C with ultrasonication for 20 minutes. Then methyl esterification was carried out with 1 ml of 2 N hydrochloric acid-methanol solution. After extracting with 2 ml of hexane, the hexane layer was washed with water. The fatty acid composition was determined by GC and GC-MS on a Unisole-3000 column. This methyl esterification method was very useful in its simplicity, rapidity and reproducibility. Second, standard strains of Legionella species were investigated. All of 9 type strains of L. pneumophila (serogroup 1-9) contained plenty of i-C 16 : 0 and 5 type strains of L. bozemanii (serogroup 1, 2), L. dumoffii, L. gormanii and L. micdadei contained much of a-C 15 : 0. It was recognized that the composition ratio of fatty acid was not influenced by incubation period and medium. Next, radar charts of 4 axial coordinate for Legionella species were drawn with the peak area ratios of 4 branched fatty acids (i-C 14 : 0, i-C 16 : 0 as iso- and a-C 15 : 0, a-C 17 : 0 as antiiso-). Consequently this radar chart of L. pneumophila differed distinctly from others. These findings suggested that the proposed method in comparison with the composition patterns of 4 branched fatty acids was useful for the rapid and chemical identification of Legionella species.
