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

Content Provider	Springer Nature Link
Author	Bourbin, M. Derenne, S. Gourier, D. Rouzaud, J. N. Gautret, P. Westall, F.
Copyright Year	2012
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.
Starting Page	569
Ending Page	585
Page Count	17
File Format	PDF
ISSN	01696149
Journal	Origins of Life and Evolution of Biospheres
Volume Number	42
Issue Number	6
e-ISSN	15730875
Language	English
Publisher	Springer Netherlands
Publisher Date	2012-12-20
Publisher Place	Dordrecht
Access Restriction	Subscribed
Subject Keyword	Archean Electron Paramagnetic Resonance Accelerated ageing Carbonaceous matter Chert Life Sciences Astrophysics and Astroparticles Earth Sciences Astronomy, Observations and Techniques Biochemistry
Content Type	Text
Resource Type	Article
Subject	Medicine Ecology, Evolution, Behavior and Systematics Space and Planetary Science

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