Estimation of methanogenesis by quantification of coenzyme F430 in marine sediments

Copyright © 2016 by The Geochemical Society of Japan. globally deposited methane hydrate is estimated to be ~100,000 Gt (Kvenvolden, 2002; Milkov, 2004), which is a potent energy resource. Since the major source of methane in the hydrate is of methanogen origin, investigation of distribution and activities of methanogens leads to deeper understanding of the starting point of methane hydrate formation as well as migration and accumulation of methane. In subsurface marine sediments, available techniques to detect methanogen’s activity are limited. Molecular biologic techniques have been used to investigate microbial community structure and function-specific gene analysis. However, in many cases methanogen have not been detected in marine sediments although methanogenesis is a major metabolic process in anoxic subseafloor sediments, suggesting either a low population of methanogens or unknown methanogens which cannot be detected with available primers (Biddle et al., 2006; Fry et al., 2008; Valentine, 2011). Analyses of archaeal membrane lipids and their isotopic composition are powerful tools to estimate biomass and source organisms. However, any membrane lipid species are not representative for methanogens. Known constituents of membrane lipids of methanogens are archaeol, cardoarchaeol, sn-2and sn-3hydroxyarchaeols, and macrocyclic archaeol (Koga et al., Estimation of methanogenesis by quantification of coenzyme F430 in marine sediments