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Induced cooperation between marine nitrifiers and anaerobic ammonium-oxidizing bacteria by incremental exposure to oxygen
Ist Teil von
Systematic and applied microbiology, 2010-11, Vol.33 (7), p.407-415
Ort / Verlag
München: Elsevier GmbH
Erscheinungsjahr
2010
Quelle
Elsevier ScienceDirect Journals
Beschreibungen/Notizen
In oxygen-limited marine ecosystems cooperation between marine nitrifiers and anaerobic ammonium-oxidizing (anammox) bacteria is of importance to nitrogen cycling. Strong evidence for cooperation between anammox bacteria and nitrifiers has been provided by environmental studies but little is known about the development of such communities, the effects of environmental parameters and the physiological traits of their constituents. In this study, a marine laboratory model system was developed. Cooperation between marine nitrifiers and anammox bacteria was induced by incremental exposure of a marine anammox community dominated by
Scalindua species to oxygen in a bioreactor set-up under high ammonium (40
mM influent) conditions. Changes in the activities of the relevant functional groups (anammox bacteria, aerobic ammonia oxidizers and nitrite oxidizers) were monitored by batch tests. Changes in community composition were followed by Fluorescence
in situ Hybridization (FISH) and by amplification and sequencing of 16S rRNA and
amoA genes. A co-culture of
Scalindua sp., an aerobic ammonia-oxidizing
Nitrosomonas-like species, and an aerobic (most likely
Nitrospira sp.) nitrite oxidizer was obtained. Aerobic ammonia oxidizers became active immediately upon exposure to oxygen and their numbers increased 60-fold. Crenarchaea closely related to the ammonia-oxidizer
Candidatus ‘Nitrosopumilus maritimus’ were detected in very low numbers and their contribution to nitrification was assumed negligible. Activity of anammox bacteria was not inhibited by the increased oxygen availability. The developed marine model system proved an effective tool to study the interactions between marine anammox bacteria and nitrifiers and their responses to changes in environmentally relevant conditions.