Fatty acid content in whole-cell hydrolysates and phospholipid fractions of pseudomonads: A taxonomic evaluation

In a comparative taxonomic study, fatty acid contents of whole-cell hydrolysates and phospholipid fractions of strains belonging to the pseudomonads were analyzed. Major fatty acids in all taxa were 16:0 and various isomers of 16:1 and 18:1. Fatty acid patterns of phospholipids were easily differentiated from whole-cell profiles by their absence of hydroxylated fatty acids. The latter constituents proved to be diagnostic markers for differentiation of the main phylogenetic lineages within the pseudomonads (rRNA groups). Based on the presence or absence of three 3-hydroxy fatty acids, 10:0 3OH, 12:0 3OH, and 14:0 3OH, the majority of the strains could be allocated to one of the four rRNA groups (I-IV) studied. In general, rRNA group I organisms were characterized by the presence of 10:0 3OH and 12:0 3OH, rRNA group II strains contained 14:0 3OH, group III strains contained 10:0 3OH and group IV strains 12:0 3OH. A numerical analysis of the whole-cell fatty acid data yielded separate entities for all four rRNA groups. When using the fatty acid contents of phospholipids, no clear differentiation between rRNA group II and III taxa and rRNA group I organisms was obtained. Both approaches, however, yielded an analogous subgrouping of rRNA group I organisms which reflected their phylogenetic relationships.