title: Community shifts of actively growing lake bacteria after N-acetyl-glucosamine addition: improving the BrdU-FACS method.
abstract: In aquatic environments, community dynamics of bacteria, especially actively growing bacteria (AGB), are tightly linked with dissolved organic matter (DOM) quantity and quality. We analyzed the community dynamics of DNA-synthesizing and accordingly AGB by linking an improved bromodeoxyuridine immunocytochemistry approach with fluorescence-activated cell sorting (BrdU-FACS). FACS-sorted cells of even oligotrophic ecosystems in winter were characterized by 16S rRNA gene analysis. In incubation experiments, we examined community shifts of AGB in response to the addition of N-acetyl-glucosamine (NAG), one of the most abundant aminosugars in aquatic systems. Our improved BrdU-FACS analysis revealed that AGB winter communities of oligotrophic Lake Stechlin (northeastern Germany) substantially differ from those of total bacteria and consist of Alpha-, Beta-, Gamma-, Deltaproteobacteria, Actinobacteria, Candidatus OP10 and Chloroflexi. AGB populations with different BrdU-fluorescence intensities and cell sizes represented different phylotypes suggesting that single-cell growth potential varies at the taxon level. NAG incubation experiments demonstrated that a variety of widespread taxa related to Alpha-, Beta-, Gammaproteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Planctomycetes, Spirochaetes, Verrucomicrobia and Chloroflexi actively grow in the presence of NAG. The BrdU-FACS approach enables detailed phylogenetic studies of AGB and, thus, to identify those phylotypes which are potential key players in aquatic DOM cycling.
authors.affiliation: 1] Department of Limnology of Stratified Lakes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin-Neuglobsow, Germany [2] Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa-shi, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Tada
authors.affiliation: 1] Department of Limnology of Stratified Lakes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin-Neuglobsow, Germany [2] Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Grossart
mesh_terms: D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D018407:Bacterial Physiological Phenomena; D044822:Biodiversity; D001973:Bromodeoxyuridine / Q000737:chemistry / Q000592:standards*; D005434:Flow Cytometry / Q000592:standards*; D005858:Germany; D005944:Glucosamine / Q000494:pharmacology*; D060106:Lakes / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012621:Seasons
chemical_list: D012336:RNA, Ribosomal, 16S; D001973:Bromodeoxyuridine; D005944:Glucosamine