Lipid biomarkers in Hamelin Pool microbial mats and stromatolites

Comprehensive lipid biomarker profiles were determined for extant intertidal columnar stromatolites and non-lithified smooth and pustular microbial mats from Hamelin Pool, Shark Bay, Western Australia. Hydrocarbons, alkyl (wax) esters, sterols, fatty acids, triterpenoids and ether-linked hydrocarbons were analysed using gas chromatography–mass spectrometry (GC–MS) and triterpenoids were analysed using high temperature GC–MS. Cyanobacterial markers were abundant in each sample and lipids diagnostic of heterotrophic bacteria, sulfate-reducing bacteria, anoxygenic phototropic bacteria and archaea were also detected. Limited input from higher plants and diatoms was observed. For the first time, 2-methylhopanoids were detected in Hamelin Pool microbial communities. The overall lipid profiles of the three sediment types were similar, suggesting that extant non-lithified microbial mats and stromatolites can comprise similar microbial communities.