Acetate conversion in anaerobic biogas reactors: Traditional and molecular tools for studying this important group of anaerobic microorganisms

Different methods were applied to study the role of aceticlastic methanogens in biogas reactors treating solid waste and wastewater. We used traditional microbiological methods, immunological and 16S rRNA ribosomal probes for detection of the methanogens. Using this approach we identified the methanogenic spp. and their activity. In biofilm system, such as the UASB reactors the presence of the two aceticlastic methanogens could be correlated to the difference in the kinetic properties of the two species. In biogas reactor treating solid wastes, such as manure or mixture of manure and organic industrial waste, only Methanosarcina spp. were identified. Methanosarcina spp. isolated from different plants had different kinetics depending on their origin. Relating the reactor performance data to measurement of the activity by conventional microbiological methods gave a good indication of the microbial status of specific trophic groups. 16S rRNA probing confirmed these observation and gave a more detailed picture of the microbial groups present.