SS2.05 Phylogenetic and Physiologic Successions in Aquatic Bacterial Communities
Date: Monday, June 10, 2002
Time: 11:30:00 AM
Location: Carson C
 
ServaisP, Univ. of Brussels, Brussels, Belgium, pservais@ulb.ac.be
Lebaron, P, , Observatoire Océanologique , Banyuls-sur-mer, France, 
Troussellier, M, , Univ. of Montpellier , Montpellier , France, 
Schäffer, H, , Univ. of Warwick, Coventry, United Kingdom, 
Muyzer, G, , Univ. of Delft, Delft, Netherlands, 
Courties, C, , Observatoire Océanologique , Banyuls-sur-mer, France, 
Bernard, L, , Observatoire Océanologique , Banyuls-sur-mer, France, 
Vives-Rego, J, , Univ. of Barcelona, Barcelona, Spain, 
 
BACTERIAL ACTIVITY AND GENETIC DIVERSITY ALONG THE SALINITY GRADIENT OF THE RHÔNE RIVER PLUME (FRANCE).
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Microbial ecological and molecular biological methods were simultaneously used to investigate the relationship between bacterial diversity and activity along an estuarine gradient. Samples were collected in the plume following a Lagrangian strategy. Phytoplanktonic and bacterial cells were enumerated by flow cytometry, bacterial activity was estimated by thymidine and leucine incorporation rates and bacterial genetic richness was analyzed by the number of DGGE bands obtained from 16S rDNA and RNA. The estuarine gradient exhibited large changes in bacterial abundances and activities. A high genetic diversity was observed in this system compared to other aquatic ecosystems. Very few DGGE bands initially found in the freshwater profile were detected in the marine end-part of the gradient. The ratio between the number of bands of RNA- and DNA-derived profiles was used as an estimation of the proportion of active populations; values of this ratio indicate that in the Rhone river only a part of the constitutive populations were active. This ratio was higher for marine communities showing that activity was distributed within a large diversity of populations.