| Titre : | Viability of differentiated epilithic bacterial communities in the River Garonne (SW France) |
| Auteurs : | Emilie Lyautey, Auteur ; Stéphanie Boulêtreau, Auteur ; Erwann Y. Madigou, Auteur ; Frederic Garabetian, Auteur |
| Type de document : | Article |
| Dans : | Hydrobiologia (637(1) JAN 2010) |
| Article en page(s) : | 207-218 |
| Résumé : | Epilithic bacterial community viability was assessed on natural biofilm assemblages from environmentally contrasting locations over a 17-months period to determine if it reflects environmental conditions or conditions within the biofilm assemblage. Vital state was assessed by membrane integrity using LIVE/DEAD(A (R)) BacLight (TM) staining kit. Samples were regularly collected in a large river, up and downstream of a large urban centre. Epilithic biomasses were similar between sites irrespective of the distinct water quality but varied temporarily, peaking up to 48 g AFDM m(-2). Bacterial community composition assessed by 16S rDNA based PCR-DGGE significantly differed between sites. Bacterial densities (median of 2.5 x 10(11) cell g AFDM(-1)) were stable whatever the sample origin or biomass. Viable bacterial fractions ranged between 13 and 83% of the total bacterial densities and were correlated with hydrological stability indicators (average of 41.9% during stable water periods, 62.4% during intermediate flow regimes and 50.0% during flow instability) and seasonal parameters. At the river section and epilithic community scales, consistent bacterial densities per unit of biomass could reflect a biofilm assemblage carrying capacity while variable membrane integrity likely integrates changes in the vital state of the community under changing environmental conditions. |



