Impact of crop management on intraspecific diversity of Pseudomonas corrugata in bulk soil

The genetic structure of Pseudomonas corrugata populations was investigated in bulk soil to evaluate the impact of crop management on the intraspecifi c diversity of this bacterium stimulated in plant rhizosphere. As these bac teria are rare in bulk soil, an immunotrapping assay was developed to isola te them from soils located in Grignon (France), where adjacent plots with s imilar soil features were cultivated under maize/wheat crop rotation or con tinuous wheat cropping. Genomic fingerprinting of 291 isolates was performe d using repetitive sequence-based polymerase chain reaction (ERIC-PCR). Mos t of these isolates (236 out of 291) were assigned to P. corrugata on the b asis of an amplified ribosomal DNA restriction analysis (ARDRA) with 12 res triction enzymes. Data were analyzed by Pearson's chi-squared tests and gen etic diversity was evaluated with specific indices for richness and evennes s. Comparison of richness or evenness diversity indices (global diversity) showed no significant difference, whereas ERIC-PCR fingerprinting data (int raspecific diversity) showed that the genetic structure of P. corrugata was significantly affected by crop management. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights r eserved.