title: Isotope array analysis of Rhodocyclales uncovers functional redundancy and versatility in an activated sludge.
abstract: Extensive physiological analyses of different microbial community members in many samples are difficult because of the restricted number of target populations that can be investigated in reasonable time by standard substrate-mediated isotope-labeling techniques. The diversity and ecophysiology of Rhodocyclales in activated sludge from a full-scale wastewater treatment plant were analyzed following a holistic strategy based on the isotope array approach, which allows for a parallel functional probing of different phylogenetic groups. Initial diagnostic microarray, comparative 16S rRNA gene sequence, and quantitative fluorescence in situ hybridization surveys indicated the presence of a diverse community, consisting of an estimated number of 27 operational taxonomic units that grouped in at least seven main Rhodocyclales lineages. Substrate utilization profiles of probe-defined populations were determined by radioactive isotope array analysis and microautoradiography-fluorescence in situ hybridization of activated sludge samples that were briefly exposed to different substrates under oxic and anoxic, nitrate-reducing conditions. Most detected Rhodocyclales groups were actively involved in nitrogen transformation, but varied in their consumption of propionate, butyrate, or toluene, and thus in their ability to use different carbon sources in activated sludge. This indicates that the functional redundancy of nitrate reduction and the functional versatility of substrate usage are important factors governing niche overlap and differentiation of diverse Rhodocyclales members in this activated sludge.
authors: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Aalborg, Denmark.
authors: Martin
authors: M
authors: Hesselsoe
authors: Stephanie
authors: S
authors: Füreder
authors: Michael
authors: M
authors: Schloter
authors: Levente
authors: L
authors: Bodrossy
authors: Niels
authors: N
authors: Iversen
authors: Peter
authors: P
authors: Roslev
authors: Per Halkjaer
authors: PH
authors: Nielsen
authors: Michael
authors: M
authors: Wagner
authors: Alexander
authors: A
authors: Loy
mesh_terms: D020562:Betaproteobacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011868:Radioisotopes / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D011868:Radioisotopes; D012722:Sewage; D002244:Carbon; D009584:Nitrogen