Abstract
The neutral lipids and phospholipids of two strains of rhizobia in their free-living state and in symbiosis with a host plant are described. The principal lipid classes found were the polymer poly-beta-hydroxybutyrate, phospholipids, free fatty acids, glycerides, methyl esters, aliphatic alcohols, and hydrocarbons. The lipids include unusual unsaturated methyl-branched and saturated methoxy-branched fatty acids. Most components were found to be common to both forms of both strains, although the proportions varied. A number of strain differences could be discerned.