The occurrence of hopanoid lipids in<i>Bradyrhizobium</i>bacteria

Abstract

Lipid extraction procedures followed by GLC and GLC-MS analysis were used to investigate the triterpenoid content in Bradyrhizobium and Rhizobium bacteria. Unlike the tested strains of Rhizobium bacteria, a range of triterpenoids e.g., squalene and different classes of hopanoid derivatives were detected in bacteria from all Bradyrhizobium strains investigated (different strains from Bradyrhizobium japonicum, Bradyrhizobium elkanii as well as Bradyrhizobium sp.). Furthermore, related compounds were identified from some hopanoid lipids (e.g., diplopterol) that carried an additional methyl group in their molecular structure. The hopanoid content was high in some strains and accounted for more than 40% of the total lipid fraction (e.g., in strains Bradyrhizobium japonicum USDA 110 and USDA 31), while other strains contained only about a tenth of that amount (e.g., Bradyrhizobium japonicum ATCC 10324 and Bradyrhizobium sp. (Lupinus) ATCC 10319).