Co-occurence of Crenarchaeota, Thermoplasmata and methanogens in anaerobic sludge digesters

International audience16S rRNA Crenarchaeota and Thermoplasmata sequences retrieved from 22 anaerobic digesters were analysed. 4.8 and 0.53 % of archaeal sequences were simultaneously affiliated to these lineages. A core of 2 operational taxonomic units (OTUs) representing 0.6 to –33.6 % of all archaeal sequences were defined for the Crenarchaeotes and identified to already known but not yet cultivable organisms in almost half of the digesters sampled. For the Thermoplasmata, apparently less abundant with 0.7 to –4.7 % of the archaeal sequences, 3 OTUs were identified. We showed here that Crenarchaeotes coexist with methanogens and are particularly abundant when Arch I lineage (also called WSA2 by Hugenholtz) is dominant in digesters. Moreover, Thermoplasmata were detected when Crenarchaeota were present. Interactions between methanogens, Crenarchaeotea and Thermoplamata were thus discussed

Single cell microbial ecophysiology with Raman-FISH

The ability to identify and characterise the roles that bacteria perform in their natural environment is a central prerequisite for understanding how ecosystems function. Traditional methods of culturing and identification are not always suitable due to the inability to grow most bacteria in pure cultures, the so-called great plate count anomaly. Recent developments in culture-independent molecular methods, coupled to microscopy-based ecophysiological analyses, are gaining increasing interest due to their ability to circumvent culture-based biases and allow physiological/phylogenetic analysis within ecological communities. Here we describe the application of Raman microspectroscopy and fluorescence in situ hybridisation (FISH) in combination with stable isotope labelling to help determine bacterial identity and function

Syntrophic Communities in Methane Formation from High Strength Wastewaters

Among the goals of environmentally sound waste treatment is the recycling of organic wastes. The most practiced options are composting and anaerobic digestion, both processes being carried out by microorganisms. This book provides an overview of the various ways microbes are doing their job and gives the reader an impression of their potential. The sixteen chapters of this book summarize the advantages and disadvantages of treatment processes, whether they are aerobic like composting or work without oxygen like anaerobic digestion for biogas (methane) production. These chapters show the potential of microorganisms to create valuable resources from otherwise wasted materials. These resources include profitable organic, humus-like soil conditioners or fertilizer components which are often suppressive to plant diseases. Composts may thus improve soil carbon sequestration, or support sustainable agriculture by reducing the need for mineral fertilizers or pesticides. If anaerobic digestion is used, the biogas produced may replace fossil fuels. Thus, proper biological waste treatment with the help of microorganisms should contribute to a reduction of anthropogenic greenhouse gas productio