|Production of methane and hydrogen by anaerobic ciliates containing symbiotic methanogens|
Fenchel, T.; Finlay, B.J. (1992). Production of methane and hydrogen by anaerobic ciliates containing symbiotic methanogens. Arch. Microbiol. 157(6): 475-480
In: Archives of Microbiology. Springer: Heidelberg; Berlin. ISSN 0302-8933, more
Anaerobes; Ciliates; Metopus Claparède & Lachmann, 1858 [WoRMS]; Marine
|Authors|| || Top |
- Fenchel, T., more
- Finlay, B.J.
Rates of methane production by three anaerobic ciliates containing symbiotic methanogens (the marine Metopus contortus and Plagiopyla frontata, and the limnic Metopus palaeformis) were quantified. Hydrogen production by normal (containing active symbionts), aposymbiotic and BES-treated cells was also measured in the case of the marine species. Methanogenesis was closely coupled to host metabolism and growth; at maximum ciliate growth rates (20°C) each methanogen produced about 1 fmol CH4 per hour corresponding to about 7, 4 and 0.35 pmol per ciliate per hour for M. contortus, P. frontata and M. palaeformis, respectively. Normal cells produced traces of H2. Hydrogen production by BES-treated or aposymbiotic cells accounted for 75 and 45% of the methane production of normal M. contortus and P. frontata cells, respectively. However, it is possible that hydrogen production was partly inhibited in the absence of methanogens. Theoretical considerations suggest that hydrogen transfer is significant to the metabolism of larger anaerobic ciliates. Ciliates with methanogens produced CH4 under microaerobic conditions due to their ability to maintain an anoxic intracellular environment at low external oxygen tensions. Methanogenesis was still detectable at a pO2 of 0.63 kPa (3 %atm sat).