Andreas Schramm

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Half of the microbial cells in the Earth's oceans are found in sediments. Many of these cells are members of the Archaea, single-celled prokaryotes in a domain of life separate from Bacteria and Eukaryota. However, most of these archaea lack cultured representatives, leaving their physiologies and placement on the tree of life uncertain. Here we show that(More)
The emission of methane (1.3 mmol of CH(4) m(-2) day(-1)), precursors of methanogenesis, and the methanogenic microorganisms of acidic bog peat (pH 4.4) from a moderately reduced forest site were investigated by in situ measurements, microcosm incubations, and cultivation methods, respectively. Bog peat produced CH(4) (0.4 to 1.7 micro mol g [dry wt] of(More)
Oxygen consumption in marine sediments is often coupled to the oxidation of sulphide generated by degradation of organic matter in deeper, oxygen-free layers. Geochemical observations have shown that this coupling can be mediated by electric currents carried by unidentified electron transporters across centimetre-wide zones. Here we present evidence that(More)
Archaeal and bacterial ammonia monooxygenase genes (amoA) had similar low relative abundances in freshwater sediment. In the rhizosphere of the submersed macrophyte Littorella uniflora, archaeal amoA was 500- to >8,000-fold enriched compared to bacterial amoA, suggesting that the enhanced nitrification activity observed in the rhizosphere was due to(More)
Rumen methanogens are major sources of anthropogenic methane emissions, and these archaea are targets in strategies aimed at reducing methane emissions. Here we show that the poorly characterised Thermoplasmata archaea in bovine rumen are methylotrophic methanogens and that they are reduced upon dietary supplementation with rapeseed oil in lactating cows.(More)
Communities of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in freshwater sediments and those in association with the root system of the macrophyte species Littorella uniflora, Juncus bulbosus, and Myriophyllum alterniflorum were compared for seven oligotrophic to mesotrophic softwater lakes and acidic heathland pools. Archaeal and bacterial ammonia(More)
Sulfate-reducing prokaryotes (SRP) cause severe problems like microbial corrosion and reservoir souring in seawater-injected oil production systems. One strategy to control SRP activity is the addition of nitrate to the injection water. Production waters from two adjacent, hot (80 degrees C) oil reservoirs, one with and one without nitrate treatment, were(More)
Earthworms emit nitrous oxide (N(2)O) via the activity of bacteria in their gut. Four N(2)O-producing facultative aerobes, ED1(T), ED5(T), MH21(T) and MH72, were isolated from the gut of the earthworm Aporrectodea caliginosa. The isolates produced N(2)O under conditions that simulated the microenvironment of the earthworm gut. ED1(T) and ED5(T) were(More)
This review summarizes the state of microscale in situ analyses of nitrification. Microsensors and fluorescence in situ hybridization (FISH) have both become important methods for microbial ecology. In combination, they have offered a variety of exciting insights into structure and activity of microbial communities, including nitrifying biofilms,(More)
The in vivo production of nitrous oxide (N(2)O) by earthworms is due to their gut microbiota, and it is hypothesized that the microenvironment of the gut activates ingested N(2)O-producing soil bacteria. In situ measurement of N(2)O and O(2) with microsensors demonstrated that the earthworm gut is anoxic and the site of N(2)O production. The gut had a pH of(More)