Anaerobiosis and Symbiosis with Bacteria in Free-living Ciliates |
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Authors: | TOM FENCHEL TED PERRY ANNE THANE |
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Affiliation: | Department of Ecology and Genetics, University of Aarhus, DK-8000 Arhus C, Denmark |
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Abstract: | SYNOPSIS. Marine, sediment-dwelling ciliates were examined for cytochrome oxidase activity by a cytochemical method and for fine structural details. Species of Plagiopylidae (Trichostomatida), i.e. Plagiopyla frontata, Sonderia vorax and Sonderia sp., and of Heterotrichida, i.e., Parablepharisma pellitum, Parablepharisma sp., Metopus contortus, Metopus vestitus and Caenomorpha capucina ; previously considered to be obligate anaerobes because of their sulfide-containing habitat, do not have cytochrome oxidase activity or mitochondria with cristae or tubuli. The evolutionary origin and significance of anaerobic ciliates is discussed. Most of the anaerobic ciliates harbor a flora of ecto- and endosymbiotic bacteria as demonstrated by transmission and scanning electron micrographs. It is speculated that the bacteria may utilize the metabolic end products of the protozoa for growth and energy yielding processes. These associations are also compared with other, previously described cases of symbiosis involving prokaryotes and protozoa. |
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Keywords: | Plagiopyla frontata Sonderia vorax Parablepharisma pellitum Metopus contortus Metopus vestitus Caenomorpha capucina ciliates anaerobiosis symbiotic bacteria cytochrome oxidase electron microscopy |
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