Experimental mineralisation in carbonate, phosphate, and silicate of the filamentous hydrogenotrophic methanogen Methanobacterium oryzae

• Methanogens are thought to be some of the most ancient organisms to have lived on Earth. Fossils of ancient mineralised filamentous forms have been described before from hydrothermal vents to sediments. The peculiarity of Archaea lies in their cell walls, where they lack the peptidoglycan layer found in Bacteria and instead have a proteinaceous S-layer that has been shown to promote mineralisation through the presence of charged polymers on the cell surface. Some methanogens, like the filamentous Methanobacterium oryzae do not have an S-layer but a cell wall made of pseudomurein, similar in structure to bacterial murein. In this work, experimental mineralisation with carbonate, phosphate, and silica on a strain of M. oryzae were analysed. Differences in the degree of morphological preservation in the various fossilisation agents were observed over a period of 3 months and chemical analyses using EDX and XRD were carried out on precipitates. Results indicate that the various minerals precipitate differently in association with the methanogens and only silica replicates the morphology with a relatively high degree of fidelity. This shows the presence of possible taphonomic biases in the rock record depending on mineralisation, size differences, and cell wall structure. Therefore, this work has important outcomes for the recognition of filamentous fossils in the rock record and on the different mineralisation mechanisms on early Earth.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Multidisciplinär geovetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geosciences, Multidisciplinary (hsv//eng)

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)