HYDROXY-FATTY ACID PROFILES OF LEGIONELLA SPECIES - DIAGNOSTIC USEFULNESS ASSESSED BY PRINCIPAL COMPONENT ANALYSIS

Twenty-nine species (76 strains) of members of the genus Legionella we re analyzed for their cellular hydroxylated fatty acids (OH-FAs). The individual patterns were unusually complex and included both monohydro xylated and dihydroxylated chains of unbranched or branched (iso and a nteiso) types. Comparison of the strain profiles by SIMCA (Soft Indepe ndent Modelling of Class Analogy) principal component analysis reveale d four main groups. Group 1 included Legionella pneumophila plus L. is raelensis strains, and group 2 included L. micdadei and L. maceacherne ii strains. These two closely related groups were characterized by the occurrence of di-OH-FAs and differed mainly in the amounts of 3-OH-a2 1:0, 3-OH-n21:0, 3-OH-n22:0, and 3-OH-a23:0. Group 3 (13 species) was distinguished by il4:0 at less than 3%, 3-OH-3-OH-n14:0 at greater tha n 5%, 3-OH-n15:0 at greater than 2%, and minute amounts of OH-FAs with chains longer than 21:0. Group 4 (12 species) was heterogeneous. Its main characteristics were the presence of 3-OH-n12:0 and 3-OH-n13:0, 3 -OH-i14:0 at greater than 5%, as well as significant amounts of 3-OH-a 21:0 and 3-OH-n21:0. The groupings obtained by OH-FA profiles were fou nd to reflect DNA-DNA homology groupings reasonably well, and the prof iles appear to be useful for differentiation of Legionella species.