Bicarbonate uptake by marine Crenarchaeota.

Biphytanyl membrane lipids and 16S rRNA sequences derived from marine Crenarchaeota were detected in shallow North Sea surface water in February 2002. To investigate the carbon fixation mechanism of these uncultivated archaea in situ (13)C bicarbonate tracer experiments were performed with this water in the absence of light. About 70% of the detected (13)C incorporation into lipids (including fatty acids and sterols) is accounted for by the crenarchaeotal biphytanyl membrane lipids. This finding indicates that marine Crenarchaeota can utilize bicarbonate or CO(2) derived thereof in the absence of light and are chemoautotrophic organisms.