Some rumen ciliates have endosymbiotic methanogens |
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Authors: | Bland J Finlay Genoveva Esteban Ken J Clarke Alan G Williams TMartin Embley Robert P Hirt |
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Institution: | Institute of Freshwater Ecology, The Ferry House, Ambleside, Cumbria, UK; Centro de Estudios Avanzados de Blanes, CSIC, Gerona, Spain; Hannah Research Institute, Ayr, UK; Natural History Museum, Cromwell Road, London, UK |
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Abstract: | Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F420 autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H2 evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates. |
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Keywords: | Rumen ciliates Endosymbiotic methanogens Methane Greenhouse gas Dasytricha Entodinium |
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