RANDOM AND REPETITIVE PRIMER AMPLIFIED POLYMORPHIC DNA ANALYSIS OF 5 SOIL AND 2 CLINICAL ISOLATES OF RAHNELLA-AQUATILIS

PCR patterns of five nitrogen-fixing soil bacterial strains isolated f rom the rhizosphere of wheat in the vicinity of Bayreuth were generate d by PCR using random and repetitive (BOX, ERIC and REP) primers. They have been compared to the patterns (obtained with the same primers) o f several Rahnella aquatilis strains (including the type strain of thi s species - R. aquatilis ATCC 33071), the strain R. aquatilis ATCC 339 89 (to whom one of our isolates has been formerly assumed to be relate d), and two clinical isolates of the same species. As outgroup strains Enterobacter agglomerans 19-78, Escherichia coli W2438 and Pantoea ag glomerans 5D representing different species of the family Enterobacter iaceae were used. By all primers used it was clearly shown that the na tural isolates belong to the species R. aquatilis. Even more, they hav e been clustered into two groups around the two ATCC strains 33071 and 33989, respectively. By these analyses, it was possible also to show that the clinical R. aquatilis strains form another, third group. In a ddition, both kinds of PCR fingerprinting (using arbitrary or repetiti ve primers) generated highly reproducible patterns when parallel react ions with total DNA extracted by different methods from independent li quid cultures of one and the same strain were performed. The patterns obtained by PCR fingerprinting of total DNA or of cells from fresh col onies or liquid cultures added to the PCR mixture did not differ signi ficantly. The RAPD and rep-APD characterization of the strains studied here is in full agreement with their taxonomical analysis performed b y other molecular methods such as micro- and macro-RFLP fingerprinting , ribotyping and 16S rDNA sequencing. On the basis of these results we recommend to apply these simple, fast and cheap methods for identific ation and discrimination of new environmental and clinical isolates of the species R. aquatilis.