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| Van Wambeke, France; Catala, P.; Pujo-pay, M.; Lebaron, P.. |
| Heterotrophic bacterioplankton abundance and production were investigated with depth (down to bathypelagic layers) and with longitude (from 4.9 degrees E to 32.7 degrees E) along a cruise track across the Mediterranean Sea in early summer 2008. Abundances and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were determined using flow cytometry. Contrary to what is generally observed, the relative importance of HNA cells, as a percent of total cells, (%HNA, range 30-69%) was inversely related to bacterial production (range 0.15-44 ngC l(-1) h(-1)) although the negative relation was weak (log-log regression r(2) = 0.19). The %HNA as well as the mean side... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24390/22404.pdf |
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| Lamy, D.; Jeanthon, C.; Cottrell, M. T.; Kirchman, D. L.; Van Wambeke, France; Ras, J.; Dahan, O.; Pujo-pay, M.; Oriol, L.; Bariat, L.; Catala, P.; Cornet-barthaux, V.; Lebaron, P.. |
| Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24398/22417.pdf |
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| Talarmin, A.; Van Wambeke, F.; Lebaron, P.; Moutin, T.. |
| Microbial transformations are key processes in marine phosphorus cycling. In this study, we investigated the contribution of phototrophic and heterotrophic groups to phosphate (Pi) uptake fluxes in the euphotic zone of the low-Pi Mediterranean Sea and estimated Pi uptake kinetic characteristics. Surface soluble reactive phosphorus (SRP) concentrations were in the range of 6–80 nmol L−1 across the transect, and the community Pi turnover times, assessed using radiolabeled orthophosphate incubations, were longer in the western basin, where the highest bulk and cellular rates were measured. Using live cell sorting, four vertical profiles of Pi uptake rates were established for heterotrophic prokaryotes (Hprok), phototrophic picoeukaryotes (Pic) and... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00269/38002/36084.pdf |
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| Talarmin, A.; Van Wambeke, France; Catala, P.; Courties, C.; Lebaron, P.. |
| The surface of the Mediterranean Sea is a low-phosphate-low-chlorophyll marine area where marine heterotrophic prokaryotes significantly contribute to the biogeochemical cycles of all biogenic elements such as carbon, notably through the mineralization of dissolved organic compounds. Cell-specific leucine incorporation rates were determined in early summer in the open stratified Mediterranean Sea. The bulk leucine incorporation rate was on average 5 +/- 4 pmol leu l(-1) h(-1) (n = 30). Cell-specific 3H-leucine incorporation rates were assayed using flow cytometry coupled to cell sorting. Heterotrophic prokaryotes (Hprok) were divided into cytometric groups according to their side scatter and green fluorescence properties: high nucleic acid containing cells... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24394/22407.pdf |
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| Auguet, Jean-christophe; Montanie, Helene; Hartmann, Hans; Lebaron, P.; Casamayor, E. O.; Catala, P.; Delmas, Daniel. |
| Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r (2) = 0.91, n = 12, p < 0.0001) to bacterial production, making this value a good predictor of active cell... |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6636.pdf |
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