title: Stable isotope probing of acetate fed anaerobic batch incubations shows a partial resistance of acetoclastic methanogenesis catalyzed by Methanosarcina to sudden increase of ammonia level.
abstract: Ammonia inhibition represents a major operational issue for anaerobic digestion. In order to refine our understanding of the terminal catabolic steps in thermophilic anaerobic digestion under ammonia stress, we studied batch thermophilic acetate fed experiments at low (0.26 g L(-1)) and high (7.00 g L(-1)) Total Ammonia Nitrogen concentrations (TAN). Although methane production started immediately for all incubations and resulted in methane yields close to stoichiometric expectations, a 62-72% decrease of methanogenic rate was observed throughout the incubation at 7.00 g L(-1) of TAN compared to 0.26 g L(-1). Stable Isotope Probing analysis of active microbial communities in (13)C-acetate fed experiments coupled to automated ribosomal intergenic spacer analysis and 16S rDNA pyrotag sequencing confirmed that microbial communities were similar for both TAN conditions. At both TAN levels, the (13)C-labeled bacterial community was mainly affiliated to Clostridia-relatives, with OPB54 bacteria being the most abundant sequence in the heavy DNA 16S rDNA pyrotag library. Sequences closely related to Methanosarcina thermophila were also abundantly retrieved in the heavy DNA fractions, showing that this methanogen was still actively assimilating labeled carbon from acetate at free ammonia nitrogen concentrations up to 916 mg L(-1). Stable isotopic signature analysis of biogas, measured in unlabeled acetate fed experiments that were conducted in parallel, confirmed that acetoclastic methanogenic pathway was dominant at both ammonia concentrations. Our work demonstrates that, besides the syntrophic acetate oxidation pathway, acetoclastic methanogenesis catalyzed by Methanosarcina can also play a major role in methane production at high ammonia levels.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; Irstea, UR HBAN, F-92761 Antony, France; Institute of Waste Treatment & Reclamation, Tongji University, Shanghai 200092, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; Institute of Waste Treatment & Reclamation, Tongji University, Shanghai 200092, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lü
authors.affiliation: Irstea, UR HBAN, F-92761 Antony, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Mazéas
authors.affiliation: Irstea, UR HBAN, F-92761 Antony, France.
authors.forename: Elie
authors.initials: E
authors.lastname: Desmond-Le Quéméner
authors.affiliation: Irstea, UR HBAN, F-92761 Antony, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Madigou
authors.affiliation: Irstea, UR HBAN, F-92761 Antony, France.
authors.forename: Angéline
authors.initials: A
authors.lastname: Guenne
authors.affiliation: Institute of Waste Treatment & Reclamation, Tongji University, Shanghai 200092, China; Minist Housing & Urban Rural Dev PR China MOHURD, Ctr Technol Res & Training Household Waste Small, Beijing, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
authors.affiliation: Irstea, UR HBAN, F-92761 Antony, France. Electronic address: theodore.bouchez@irstea.fr.
authors.forename: Théodore
authors.initials: T
authors.lastname: Bouchez
authors.affiliation: Institute of Waste Treatment & Reclamation, Tongji University, Shanghai 200092, China; Minist Housing & Urban Rural Dev PR China MOHURD, Ctr Technol Res & Training Household Waste Small, Beijing, China. Electronic address: solidwaste@tongji.edu.cn.
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D002247:Carbon Isotopes; D002384:Catalysis; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods*; D053858:Metabolic Networks and Pathways; D008697:Methane / Q000378:metabolism*; D017020:Methanosarcina / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013997:Time Factors
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D000641:Ammonia; D004247:DNA; D008697:Methane
keywords: Acetate-utilizing bacteria; Acetotrophic methanogens; Ammonia inhibition; Metabolic pathway dynamics; Pyrosequencing; Stable isotope signature