Oxygen tolerance and occurrence of superoxide dismutase as an antioxidant enzyme in Metopus es.

The free-living anaerobic ciliate Metopus es was found to possess moderate tolerance to oxygen. Direct oxygen exposure led to the death of >80% of the population within 24h, but the remaining cells exhibited some oxygen tolerance and survived up to 4 days without any growth. Survival of the ciliate was observed only in an oxygen tension up to 7.

Methanosaeta sp., the major archaeal endosymbiont of Metopus es.

Epifluorescence microscopy and whole cell in situ hybridization analysis revealed the presence of Methanosaeta sp. as endosymbionts in Metopus es. Direct microscopic observation under epifluorescent microscope showed the presence of long slender rods with an average length of 3.

Involvement of protozoa in anaerobic wastewater treatment process.

It is only very rarely recognised in literature that anaerobic reactors may contain protozoa in addition to various bacterial and archeal groups. The role of protozoa in anaerobic degradation was studied in anaerobic continuous stirred tank reactors (CSTR) and batch tests. Anaerobic protozoa, especially the ciliated protozoa, have direct influence on the performance of CSTR at all organic loading rates (1-2g CODl(-1)d(-1)) and retention times (5-10 days).

Anaerobic protozoa and their growth in biomethanation systems.

This study was to investigate growth of protozoa and its influence on biodegradation in anaerobic treatment systems. It was done by specifically controlling and monitoring growth of protozoa versus degradation in continuous stirred anaerobic reactors and batch anaerobic reactors. Occurrence of a diverse protozoa population such as the ciliates, Prorodon, Vorticella, Cyclidium, Spathidium, Loxodes, Metopus were observed in stable anaerobic systems and the flagellates, Rhynchomonas, Naeglaria, Amoeboflagellates, Tetramitus, Trepomonas and Bodo during increased VFA concentration and affected periods of biomethanation.

Isolation and culturing of a most common anaerobic ciliate, Metopus sp.

The study includes isolation of anaerobic ciliate, Metopus sp. from an anaerobic reactor and development of its monoculture under laboratory conditions. Separation by centrifugation followed by micromanipulatory isolation resulted in obtaining pure Metopus culture with less bacterial contamination.