Changes in methanogenic substrate utilization and communities with depth in a salt-marsh, creek sediment in southern England

A combined biogeochemical and molecular genetic study of creek sediments (down to 65 cm depth) from Arne Peninsula salt-marsh (Dorset, UK) determined the substrates used for methanogenesis and the distribution of the common methanogens, Methanosarcinales and Methanomicrobiales capable of metabolisin...

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Bibliographic Details
Published in:Estuarine, coastal and shelf science coastal and shelf science, 2012, Vol.96, p.170-178
Main Authors: John Parkes, R., Brock, Fiona, Banning, Natasha, Hornibrook, Edward R.C., Roussel, Erwan G., Weightman, Andrew J., Fry, John C.
Format: Article
Language:English
Subjects:
Acetates
Animal and plant ecology
Animal, plant and microbial ecology
Bacteriology
Bicarbonates
Biodiversity and Ecology
Biological and medical sciences
Brackish
Brackish water ecosystems
Carbon dioxide
Coastal
Ecology, environment
Ecosystems
Environmental Sciences
Fundamental and applied biological sciences. Psychology
Global Changes
Life Sciences
Methane
methanogenesis
methanogenic substrates
methanogens
Methanomicrobiales
Methanosaeta
Methanosarcinales
Methyl alcohol
Microbiology and Parasitology
salt-marsh sediments
Sediments
Symbiosis
Synecology
Utilization
δ13C-CH 4 values
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Summary:A combined biogeochemical and molecular genetic study of creek sediments (down to 65 cm depth) from Arne Peninsula salt-marsh (Dorset, UK) determined the substrates used for methanogenesis and the distribution of the common methanogens, Methanosarcinales and Methanomicrobiales capable of metabolising these substrates. Methane concentrations increased by 11 cm, despite pore water sulphate not being removed until 45 cm. Neither upward methane diffusion or anaerobic oxidation of methane seemed to be important in this zone. In the near-surface sulphate-reduction zone (5–25 cm) turnover time to methane for the non-competitive methanogenic substrate trimethylamine was most rapid (80 days), and were much longer for acetate (7900 days), methanol (40,500 days) and bicarbonate (361,600 days). Methylamine-utilizing Methanosarcinales were the dominant (60–95%) methanogens in this zone. In deeper sediments rates of methanogenesis from competitive substrates increased substantially, with acetate methanogenic rates becoming ∼100 times greater than H 2/CO 2 methanogenesis below 50 cm. In addition, there was a dramatic change in methanogen diversity with obligate acetate-utilizing, Methanosaeta related sequences being dominant. At a similar depth methanol turnover to methane increased to its most rapid (1700 days). This activity pattern is consistent with deeper methanogen populations (55 cm) being dominated by acetate-utilizing Methanosaeta with H 2/CO 2 and alcohol-utilizing Methanomicrobiales also present. Hence, there is close relationship between the depth distribution of methanogenic substrate utilization and specific methanogens that can utilize these compounds. It is unusual for acetate to be the dominant methanogenic substrate in coastal sediments and δ 13C-CH 4 values (−74 to −71‰) were atypical for acetate methanogenesis, suggesting that common stable isotope proxy models may not apply well in this type of dynamic anoxic sediment, with multiple methanogenic substrates.
ISSN:0272-7714
1096-0015
DOI:10.1016/j.ecss.2011.10.025