Bacteriohopanepolyols in hydrothermal vent biogenic silicates

Biogenic silicates from the Taupo Volcanic Zone (North Island, New Zealand) are shown to contain a number of unusual polyfunctionalised bacteriohopanepolyols. Hopanoid fractions isolated from the Rotokawa hot spring (80–82 °C) contained significant amounts of 32,35-anhydrobacteriohopanetetrol and two isomers of a related trihydroxylated compound. The origin of these unusual hopanoid side chains is unclear and they may result either from novel biosynthetic or diagenetic transformation pathways of known biohopanoid precursors such as bacteriohopanetetrol (via cyclisation) or reductive removal of adenine from adenosylhopane.