SS2.05 Phylogenetic and Physiologic Successions in Aquatic Bacterial Communities
Date: Monday, June 10, 2002
Time: 3:00:00 PM
Location: Carson C
 
PernthalerA, Max-Planck-Institute for Marine Microbiology, Bremen, Germany, aperntha@mpi-bremen.de
Pernthaler, J, , Max-Planck-Institute for Marine Microbiology, Bremen, Germany, jperntha@mpi-bremen.de
Amann, R, , Max-Planck-Institute for Marine Microbiology, Bremen, Germany, ramann@mpi-bremen.de
 
Detection of DNA-synthesizing bacterial populations in coastal North Sea plankton
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We present a method for the microscopic identification of DNA synthesizing cells in bacterioplankton samples. After incubation with the halogenated thymidine analogon bromodeoxyuridin (BrdU), environmental bacteria were identified by fluorescence in situ hybridization (FISH) with horseradish peroxidase (HRP) linked oligonucleotide probes. Tyramide signal amplification (TSA) was used to preserve the FISH staining during the subsequent immunocytochemical detection of BrdU incorporation. DNA-synthesizing cells were visualized by means of a HRP-labeled antibody fab fragment and a second TSA step. We applied our protocol to samples of 1.2 Ám-prefiltered North Sea surface water collected during early autumn. After 4 h of incubation BrdU-incorporation was detected in 3.4% of all bacterial cells. Within 20 h the size of the DNA-synthesizing fraction increased to 14.2%. A contrasting development of total abundances and of BrdU labelling patterns were observed in populations of Roseobacter, SAR86 and Alteromonas during 20 hours of enrichment.