Molecular characterization of rhizosphere and clinical isolates of Burkholderia cepacia

Four Burkholderia cepacia strains isolated from the rhizosphere and pathological samples of infected human patients were characterized at the molecular level by different methodologies, including the determination of 16S ribosomal rDNA sequence, restriction endonuclease analysis of total DNA, random amplified polymorphic DNA fingerprinting and Southern hybridization with gene probes for nitrogen fixation and siderophore synthesis. The results indicate that the four strains cluster together within genus Burkholderia, but differ from one another. The DNA from the four strains hybridized to the nifA gene probe from Klebsiella pneumoniae, and an appreciable homology with the nifHDK structural genes of Azospirillum brasilense was demonstrated for one rhizosphere strain. Although the four isolates produced an ornibactin-like siderophore, they did not give hybridization with the pvdA probe for hydroxamate biosynthesis from Pseudomonas aeruginosa