Hopanoid inventory of Rhodoplanes spp.

Abstract

Hopanoids are pentacyclic triterpenoid lipids and are important for bacterial membrane stability and functioning. These pentacyclic triterpenoids of hopane series are biomarkers for eubacteria and can be used as chemotaxonomic markers. Anoxygenic phototrophic bacteria are good producers of hopanoids, and their inventory to date is restricted to a few members. Rhodoplanes spp. are phototrophic prokaryotes which grow and thrive in subsurface and sediment environments. A study on the diversity of hopanoids of several species of Rhodoplanes revealed a rich diversity of hopanoids with carbon length of C30/C31 and C35. Hop-22(29)-ene (II), diplopterol (V), tetrahymanol (VII), 2-methyldiplopterol (VI), 2-methyltetrahymanol (VIII), bacteriohopanetetrol (IX), bacteriohopaneaminotriol (X) and bacteriohopanepolyols [BHP-492 (XIII), BHP-550 (XIV), BHP-508 (XII)] are the major hopanoids of the genus Rhodoplanes. Tetrahymanol (VII) content is high (38–60 %) among all the members, except for Rhodoplanes elegans. Hopanoid fingerprints allowed differentiation of species of the genus Rhodoplanes. Statistical analyses also indicate hopanoids as good chemotaxonomic markers to distinguish species of the genus Rhodoplanes.