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Science. 2002 Jun 28;296(5577):2407-10.

Ongoing modification of Mediterranean Pleistocene sapropels mediated by prokaryotes.

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  • 1Paleomicrobiology Group, Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Post Office Box 2503, D-26111 Oldenburg, Germany.


Late Pleistocene organic-rich sediments (sapropels) from the eastern Mediterranean Sea harbor unknown, metabolically active chemoorganotrophic prokaryotes. As compared to the carbon-lean intermediate layers, sapropels exhibit elevated cell numbers, increased activities of hydrolytic exoenzymes, and increased anaerobic glucose degradation rates, suggesting that microbial carbon substrates originate from sapropel layers up to 217,000 years old. 16S ribosomal RNA gene analyses revealed that as-yet-uncultured green nonsulfur bacteria constitute up to 70% of the total microbial biomass. Crenarchaeota constitute a smaller fraction (on average, 16%). A slow but significant turnover of glucose could be detected. Apparently, sapropels are still altered by the metabolic activity of green nonsulfur bacteria and crenarchaeota.

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