Biological methane production under putative Enceladus-like conditions.

The detection of silica-rich dust particles, as an indication for ongoing hydrothermal activity, and the presence of water and organic molecules in the plume of Enceladus, have made Saturn's icy moon a hot spot in the search for potential extraterrestrial life. Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus, considering that both molecular hydrogen (H) and methane (CH) have been detected in the plume. Here we show that a methanogenic archaeon, Methanothermococcus okinawensis, can produce CH under physicochemical conditions extrapolated for Enceladus.

The physiology of trace elements in biological methane production.

Trace element (TE) requirements of Methanothermobacter okinawensis and Methanothermobacter marburgensis were examined in silico, and using closed batch and fed-batch cultivation experiments. In silico analysis revealed genomic differences among the transport systems and enzymes related to the archaeal Wood-Ljungdahl pathway of these two methanogens. M.