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Applied and Environmental Microbiology, August 2006, p. 5274-5282, Vol. 72, No. 8
0099-2240/06/$08.00+0     doi:10.1128/AEM.00863-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Virus-Bacterium Interactions in Water and Sediment of West African Inland Aquatic Systems

Yvan Bettarel,^1* Marc Bouvy,² Claire Dumont,³ and Télesphore Sime-Ngando³

UR 167 CYROCO, Centre IRD de Bel Air, Route des Hydrocarbures, BP 1386, Dakar, Senegal,¹ UR 167 CYROCO, Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, France,² Université Blaise Pascal, Laboratoire de Biologie des Protistes, UMR CNRS 6023, 63177 Aubière Cedex, France³

Received 12 April 2006/ Accepted 18 May 2006

The ecology of virioplankton in tropical aquatic ecosystems is poorly documented, and in particular, there are no references concerning African continental waters in the literature. In this study, we examined virus-bacterium interactions in the pelagic and benthic zones of seven contrasting shallow inland waters in Senegal, including one hypersaline lake. SYBR Gold-stained samples revealed that in the surface layers of the sites, the numbers of viruses were in the same range as the numbers of viruses reported previously for productive temperate systems. Despite high bacterial production rates, the percentages of visibly infected cells (as determined by transmission electron microscopy) were similar to the lowest percentages (range, 0.3 to 1.1%; mean, 0.5%) found previously at pelagic freshwater or marine sites, presumably because of the local environmental and climatic conditions. Since the percentages of lysogenic bacteria were consistently less than 8% for pelagic and benthic samples, lysogeny did not appear to be a dominant strategy for virus propagation at these sites. In the benthic samples, viruses were highly concentrated, but paradoxically, no bacteria were visibly infected. This suggests that sediment provides good conditions for virus preservation but ironically is an unfavorable environment for proliferation. In addition, given the comparable size distributions of viruses in the water and sediment samples, our results support the paradigm that aquatic viruses are ubiquitous and may have moved between the two compartments of the shallow systems examined. Overall, this study provides additional information about the relevance of viruses in tropical areas and indicates that the intensity of virus-bacterium interactions in benthic habitats may lower than the intensity in the adjacent bodies of water.

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* Corresponding author. Mailing address: Institut de Recherche pour le Developpement (IRD), Centre de Bel Air, UR 167 CYROCO, BP 1386, Dakar, Senegal. Phone: 221 849 33 07. Fax: 221 832 16 75. E-mail: bettarel{at}ird.sn.

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Applied and Environmental Microbiology, August 2006, p. 5274-5282, Vol. 72, No. 8
0099-2240/06/$08.00+0     doi:10.1128/AEM.00863-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

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