Methanogenic metabolic pathways and microbial population dynamic during municipal solid waste anaerobic digestion as revieled by stable isotope monitoring and fluorecent in situ hybridization
Résumé
French and Chinese reconstituted municipal solid wastes were incubated anaerobically under mesophilic conditions (35°C). Standard physicochemical parameters were monitored together with CH4 and CO2 stable carbon isotopic signatures. Fluorescent in situ hybridization (FISH) observations were performed during those experiments in order to monitor archaeal populations. As aceticlastic methanogenesis results in a smaller fractionation against 13C than, hydrogenothrophic methanogenesis methane stable carbon isotope composition (δ13C) can be used to differentiate those two different methanogenic metabolic pathways. CH4 stable carbon isotope composition evolution indicated a succession of methanogenic metabolism during the anaerobic digestion of municipal solid wastes (i.e. hydrogenotrophic, aceticlastic and mixture of both metabolisms). The same metabolic pathways succession was observed in different incubations using different inocula (sewage sludge, landfill leachate) and different kind of municipal solid waste (French and Chinese). Methanosarcinaceae were methanogens mainly involved in methane production.