Publication Date:
2012-03-20
Description:
Two decades of scientific ocean drilling have demonstrated widespread microbial life in deep sub-seafloor sediment, and surprisingly high microbial-cell numbers. Despite the ubiquity of life in the deep biosphere, the large community sizes and the low energy fluxes in this vast buried ecosystem are not yet understood. It is not known whether organisms of the deep biosphere are specifically adapted to extremely low energy fluxes or whether most of the observed cells are in a dormant, spore-like state. Here we apply a new approach--the D:L-amino-acid model--to quantify the distributions and turnover times of living microbial biomass, endospores and microbial necromass, as well as to determine their role in the sub-seafloor carbon budget. The approach combines sensitive analyses of unique bacterial markers (muramic acid and D-amino acids) and the bacterial endospore marker, dipicolinic acid, with racemization dynamics of stereo-isomeric amino acids. Endospores are as abundant as vegetative cells and microbial activity is extremely low, leading to microbial biomass turnover times of hundreds to thousands of years. We infer from model calculations that biomass production is sustained by organic carbon deposited from the surface photosynthetic world millions of years ago and that microbial necromass is recycled over timescales of hundreds of thousands of years.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lomstein, Bente Aa -- Langerhuus, Alice T -- D'Hondt, Steven -- Jorgensen, Bo B -- Spivack, Arthur J -- England -- Nature. 2012 Mar 18;484(7392):101-4. doi: 10.1038/nature10905.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioscience, Section for Microbiology, Aarhus University, Building 1540, Ny Munkegade 114, DK-8000 Aarhus C, Denmark. bente.lomstein@biology.au.dk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22425999" target="_blank"〉PubMed〈/a〉
Keywords:
Altitude
;
Amino Acids/analysis/chemistry/metabolism
;
Aquatic Organisms/chemistry/growth & development/*isolation & purification
;
Archaea/chemistry/cytology/*growth & development/isolation & purification
;
Bacteria/chemistry/cytology/*growth & development/isolation & purification
;
Biomarkers/analysis
;
*Biomass
;
Carbon/metabolism
;
Cell Wall/chemistry
;
Geologic Sediments/*microbiology
;
Muramic Acids/analysis
;
Oceans and Seas
;
Oxidation-Reduction
;
Peru
;
Photosynthesis
;
Picolinic Acids/analysis
;
Seawater/*microbiology
;
Spores, Bacterial/chemistry/growth & development/isolation & purification
;
Time Factors
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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