Lipidomics Based Microbial Ecology Snapshot of Ophiolitic Rocks

Energy from active serpentinization processes potentially fuelled the origin of life on Earth, thus, if serpentinite-impacted sites facilitate microbial habitability, it is important to understand the source and retention of biological signatures in serpentine rocks. Investigating biological signatures in terrestrial analogues of serpentinite-impacted environments is also essential for interpreting molecular signature preservation on extra-terrestrial bodies.

To expand knowledge on the types of biological signatures directly derived from living microorganisms (intact polar lipids, IPLs), and both living and dead microorganisms (core lipids), mass spectrometry analysis was performed on Chimaera serpentinite rocks from Antalya Province, Turkey. Brucite rocks were dominated by IPLs from fungal, eukaryotic origin but in contrast, travertine samples had IPL profiles consistent with a mixed fungal, archaeal and bacterial community. The abundance and diversity of archaeal IPLs was significantly higher in the travertine compared to the brucite, and the abundance of archaeal IPLs inside the travertine rock was highest. Archaeal specific core lipids identified inside the brucite rock were not observed as IPL counterparts, suggesting the presence of a non-viable or fossil archaeal community. Comparing IPL profiles with core lipids can discriminate between living microbial communities, necromass, and fossils to combine as a promising molecular tool for identification and interpretation of bio-signatures in serpentinite-impacted sites. Continuing survey of serpentinization samples on Earth can act as analogue environments and provide valuable insight into microbial habitability on Mars and other planetary objects.