title: Effect of salinity on temporal and spatial dynamics of ammonia-oxidising bacteria from intertidal freshwater sediment.
abstract: Temporal and spatial dynamics within an ammonia-oxidising community from intertidal, freshwater sediments were studied in microcosms simulating flooding twice a day with fresh, brackish and marine waters. The microcosms had been filled with the upper 5 cm of intertidal freshwater sediment from the river Scheldt. Changes in community composition were examined by denaturing gradient gel electrophoresis of amplified DNA from the community. In the first week of incubation the initially present members of the Nitrosomonas oligotropha lineage were replaced by other members of the same lineage in the top layer of the sediment subjected to flooding with freshwater. Prolonged incubation extended niche differentiation to a depth of 5 cm. In the microcosms flooded with saline media, the initially present members of the N. oligotropha lineage were replaced by strains belonging to the Nitrosomonas marina lineage, but only in the top 1cm. Shift in community composition occurred earlier in the marine microcosms than in the brackish microcosms and was slower than the change in the freshwater microcosms. Irrespective of the nature of the flooding medium, shifts in community composition were always consistent among replicate microcosms. We conclude that salinity is an important steering factor in niche differentiation among ammonia-oxidising bacteria and also that changes within the community of this functional group of bacteria may occur at different rates.
authors.affiliation: Netherlands Institute of Ecology (NIOO-KNAW), Centre for Limnology, Department of Microbial Ecology, Rijksstraatweg 6, 3631 AC Nieuwersluis, The Netherlands. m.coci@nioo.knaw.nl
authors.forename: Manuela
authors.initials: M
authors.lastname: Coci
authors.forename: Daniela
authors.initials: D
authors.lastname: Riechmann
authors.forename: Paul L E
authors.initials: PL
authors.lastname: Bodelier
authors.forename: Stefania
authors.initials: S
authors.lastname: Stefani
authors.forename: Gabriel
authors.initials: G
authors.lastname: Zwart
authors.forename: Hendrikus J
authors.initials: HJ
authors.lastname: Laanbroek
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004586:Electrophoresis / Q000379:methods; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D010084:Oxidation-Reduction; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D000641:Ammonia