δ13C-δD distribution of lipid biomarkers in a bacterial mat from a hot spring in Miyagi Prefecture, NE Japan

Bacterial communities often develop with distinct metabolisms in hot springs using various chemical substrates. The carbon and hydrogen isotopic compositions of characteristic lipid biomarkers such as C-16 1 and C-20 1 fatty acids (FAs) have been determined in a bacterial mat at the Naruko hot spring, Japan. The C-20 1 FA is extremely enriched in C-13 (-0.57 parts per thousand) and derives from hydrogen-oxidizing bacteria which fix carbon via the reversed tricarboxylic acid cycle. On the other hand, the C-16 1 FA has a delta C-13 value of -36 8 parts per thousand, consistent with an origin in sulfur-oxidizing bacteria utilizing the Calvin cycle for carbon fixation The C-20 1 FA is more depleted in D (-469 parts per thousand) by ca. 300 parts per thousand than the C-16 (1) FA (-173 parts per thousand), suggesting a D-depleted hydrogen pool (NADH or NADPH) for lipid synthesis by the hydrogen-oxidizing bacteria The distinct delta C-13-delta D distribution of lipid biomarkers is useful for clarifying the metabolic pathways between different organisms in a bacterial ecosystem in hot springs. (C) 2009 Elsevier Ltd. All rights reserved