%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Bouvy, Marc
%A Bettarel, Yvan
%A Bouvier, C.
%A Domaizon, I.
%A Jacquet, S.
%A Le Floc'h, E.
%A Montanie, H.
%A Mostajir, B.
%A Sime-Ngando, T.
%A Torréton, Jean-Pascal
%A Vidussi, F.
%A Bouvier, Thierry
%T Trophic interactions between viruses, bacteria and nanoflagellates under various nutrient conditions and simulated climate change
%D 2011
%L fdi:010053635
%G ENG
%J Environmental Microbiology
%@ 1462-2912
%M ISI:000292308500014
%N 7
%P 1842-1857
%R 10.1111/j.1462-2920.2011.02498.x
%U https://www.documentation.ird.fr/hor/fdi:010053635
%> https://www.documentation.ird.fr/intranet/publi/2011/07/010053635.pdf
%V 13
%W Horizon (IRD)
%X Population dynamics in the microbial food web are influenced by resource availability and predator/parasitism activities. Climatic changes, such as an increase in temperature and/or UV radiation, can also modify ecological systems in many ways. A series of enclosure experiments was conducted using natural microbial communities from a Mediterranean lagoon to assess the response of microbial communities to top-down control [grazing by heterotrophic nanoflagellates (HNF), viral lysis] and bottom-up control (nutrients) under various simulated climatic conditions (temperature and UV-B radiations). Different biological assemblages were obtained by separating bacteria and viruses from HNF by size fractionation which were then incubated in whirl-Pak bags exposed to an increase of 3 C and 20% UV-B above the control conditions for 96 h. The assemblages were also provided with an inorganic and organic nutrient supply. The data show (i) a clear nutrient limitation of bacterial growth under all simulated climatic conditions in the absence of HNF, (ii) a great impact of HNF grazing on bacteria irrespective of the nutrient conditions and the simulated climatic conditions, (iii) a significant decrease in burst size (BS) (number of intracellular lytic viruses per bacterium) and a significant increase of VBR (virus to bacterium ratio) in the presence of HNF, and (iv) a much larger temperature effect than UV-B radiation effect on the bacterial dynamics. These results show that top-down factors, essentially HNF grazing, control the dynamics of the lagoon bacterioplankton assemblage and that short-term simulated climate changes are only a secondary effect controlling microbial processes.
%$ 036 ; 021