ASSESSING SIDE-EFFECTS OF MICROPOLLUTANTS ON THE SOIL MICROFLORA

The voluntary or accidental spread of xenobiotic compounds or heavy me tals may have subsequent unwanted effects on non-target organisms. In this way, all soil micro-organisms are indirectly exposed to repeated pesticide treatments, to sewage sludge landspreading and to accidental leaching. Assessment of micropollutant impacts requires either the gl obal description of their effects on the total soil microflora, or the study of the behaviour of some bioindicator groups. The global descri ption is generally based on the measurements of soil biomass and its t urnover, the enumeration of the cultivable microflora, or the determin ation of soil microbial activities. Other methods aim to describe and characterise the evolution of the phenotypical (Biolog fingerprints, p hospholipid fatty acid composition of soil communities) or genotypical biodiversity (diversity of soil DNA or 16S rRNA genes). Finally, bioi ndicators tan be used to assess the of micropollutants. Functional mic robial groups (groups involved in a specific activity of agronomic rel evance) or specific groups (a given microbial species which tan be det ected in soil or cultivated on selective media) can constitute potenti al bioindicators. However to be meaningful, such indicators must be se nsitive and present reproducible results in various environmental cond itions.