Contribution by the methanogenic endosymbionts of anaerobic ciliates to methane production in Dutch freshwater sediments

Biogenic methane contributes substantially to the atmospheric methane concentration and thus to global warming. This trace gas is predominantly produced by strictly anaerobic methanogenic archaea, which thrive in the most divergent ecological niches, e. g. paddy fields, sediments, landfills, and the digestive tract of various animals. Methanogenic archaea also live as endosymbionts in the cytoplasm of anaerobic protozoa. In marine sediments these endosymbionts can contribute up to 90% to the overall rate of methanogenesis, whereas their role of in freshwater sediments is largely unknown. Here we describe the results of a one year's survey of the methanogenesis by endosymbiotic methanogens in four different Dutch freshwater sediments. The abundance of anaerobic protozoa, in particular ciliates, the methane production rates by the ecosystem and by the protists, and a number of abiotic parameters were measured. A novel method (heatshock for 5 min) for estimating the contribution by endosymbiotic methanogens was established. Our results reveal large fluctuations of ciliate abundance throughout the year, but on average, only minor contributions by methanogenic endosymbionts to the total methanogenesis in these environment

Hydrogen and Carbon Monoxide-Utilizing Kyrpidia spormannii Species From Pantelleria Island, Italy

Volcanic and geothermal areas are hot and often acidic environments that emit geothermal gasses, including H2, CO and CO2. Geothermal gasses mix with air, creating conditions where thermoacidophilic aerobic H2- and CO-oxidizing microorganisms could thrive. Here, we describe the isolation of two Kyrpidia spormannii strains, which can grow autotrophically by oxidizing H2 and CO with oxygen. These strains, FAVT5 and COOX1, were isolated from the geothermal soils of the Favara Grande on Pantelleria Island, Italy. Extended physiology studies were performed with K. spormannii FAVT5, and showed that this strain grows optimally at 55\ub0C and pH 5.0. The highest growth rate is obtained using H2 as energy source (\u3bcmax 0.19 \ub1 0.02 h\u20131, doubling time 3.6 h). K. spormannii FAVT5 can additionally grow on a variety of organic substrates, including some alcohols, volatile fatty acids and amino acids. The genome of each strain encodes for two O2-tolerant hydrogenases belonging to [NiFe] group 2a hydrogenases and transcriptome studies using K. spormannii FAVT5 showed that both hydrogenases are expressed under H2 limiting conditions. So far no Firmicutes except K. spormannii FAVT5 have been reported to exhibit a high affinity for H2, with a Ks of 327 \ub1 24 nM. The genomes of each strain encode for one putative CO dehydrogenase, belonging to Form II aerobic CO dehydrogenases. The genomic potential and physiological properties of these Kyrpidia strains seem to be quite well adapted to thrive in the harsh environmental volcanic conditions

Effect of dietary changes on the bacteriophage population in the rumen of sheep

Item does not contain fulltext4th Symposium on Gut Microbiology, 21 juni 200

Contribution by the methanogenic endosymbionts of anaerobic ciliates to methane production in Dutch freshwater sediments

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(endo)symbiotic methanogenic archaea

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Methanogens in the gastro-intestinal tract of animals

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Fecal methanogens and vertebrate evolution

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Methane production by terrestrial arthropods.

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High prevalence of the parasite sphaerothecum destruens in the invasive topmouth gudgeon pseudorasbora parva in the netherlands, a potential threat to

Contains fulltext : 123436.pdf (publisher's version ) (Open Access

Contribution by the methanogenic endosymbionts of anaerobic ciliates to methane production in Dutch freshwater sediments

Item does not contain fulltex