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RESEARCH PRODUCT

Response of soil bacterial community structure to successive perturbations of different types and intensities

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SummaryIn soil, genetic structure modifications of indigenousbacterial community consecutively to a severe stress(mercury contamination) were delayed when thecommunity was pre-exposed to various minor per-turbations (heat, copper and atrazine). Such minorperturbations induced transitory community struc-ture modifications leading to an increase of commu-nity stability towards a severe mercury stress. Theseresults illustrated well the short-term pre-adaptationprocess for bacterial community hypothesizing thatcommunity submitted to perturbations become moreresistant to withstand another stress. Compared with other environmental matrices of the bio-sphere, soils are considered as the main reservoirs ofmicroorganisms and are continuously submitted to envi-ronmental and anthropogenic perturbations which canlead to serious modifications of microbial taxonomic andfunctional diversity (Baath et al ., 1998). Consequently, thecapacity of adaptation, in terms of resistance and resil-ience, of indigenous microbial community to environmen-tal stresses directly influences the maintenance of soilfunctions and therefore the sustainability of soil quality(Griffiths