Distribution and phylogenetic significance of 27-hydroxy-octacosanoic acid in lipopolysaccharides from bacteria belonging to the alpha-2 subgroup of Proteobacteria.

Lipopolysaccharides (LPSs) from a number of bacteria belonging to the alpha-2 subgroup of the class Proteobacteria were screened for the presence of 27-hydroxy-octacosanoic acid (27-OH-28:0). With few exceptions, most of the bacteria contained 27-OH-28:0 in their lipid A fractions. In addition, some of the bacteria contained other n-2-hydroxylated long-chain fatty acids hitherto not reported. The distribution of 27-OH-28:0 was restricted to the alpha-2 subgroup. LPSs from members of the other subgroups (the beta and gamma subgroups), including some well-characterized enterobacterial LPSs, were devoid of 27-OH-28:0. Our results indicate that the presence of n-2-hydroxylated long-chain fatty acids in LPSs might be used as a chemophylogenetical marker.