Long-term survival of methanogens of an anaerobic digestion sludge under starvation and temperature variation
Kim, T.G.; Yi, T.; Lee, J.-H.; Cho, K.-S.
Journal of Environmental Biology 36(2): 371-375
2015
ISSN/ISBN: 0254-8704 PMID: 25895258 Document Number: 684699
To investigate starvation effect on methanogen community, two identical membrane reactors were continuously operated for 84 consecutive days, with a temperature change from 50 degrees C to 20 degrees C. Continuous feeding washed out 97% biomass from reactors during the experimental period. Quantitative PCR, using mcrA genes, indicated that the methanogen abundance decreased from 7.0 x 10(7) to 1.2 x 10(7) mcrA copies ml(-1) (volume basis) at 50 degrees C, and then increased to 4.4 x 10(7) mcrA copies ml(7) at 20 degrees C (p<0.05). Correspondence analysis indicated that methanogen communities were distinctly grouped by each temperature. Canonical correspondence analysis indicated that temperature showed a significant correlation with the methanogen community composition. These results suggest that methanogens can survive for a long time (at least more than 84 days) under starvation conditions, and that temperature could be a primary factor determining the density and community of methanogens.