Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts - Archive ouverte HAL Access content directly
Journal Articles Origins of Life and Evolution of Biospheres Year : 2012

Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts

(1) , (1) , (2) , (3) , (4) , (5)
1
2
3
4
5

Abstract

Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.
Fichier principal
Vignette du fichier
Bourbin-Origins-2012.pdf (585.42 Ko) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

insu-00767794 , version 1 (05-02-2013)

Identifiers

Cite

Mathilde Bourbin, Sylvie Derenne, Didier Gourier, Jean-Noël Rouzaud, Pascale Gautret, et al.. Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts. Origins of Life and Evolution of Biospheres, 2012, 42 (6), pp.569-585. ⟨10.1007/s11084-012-9320-3⟩. ⟨insu-00767794⟩
358 View
395 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More