2,6,10,15,19-Pentamethylicosenes in Methanolobus bombayensis, a marine methanogenic archaeon, and in Methanosarcina mazei

2,6,10,15,19-Pentamethylicosenes (PMEs) containing three to five double bonds have been found in the methanogenic archaea Methanosarcina mazei (DSM 3338), a strain isolated from sewage sludge, and in Methanolobus bombayensis (OCM 438), a non-extremophilic archaeon isolated from a marine sediment. This finding gives additional support for the use of compounds with the PME carbon skeleton as markers for methanogenic activity in marine environments.