Evaluation of tRNA intergenic length polymorphism (tDNA-pCR) for the differentiation of the members of the Burkholderia cepacia complex

Diversity of rhizobial bacteria isolated from nodules of the Gypsophyte Ononis tridentata L. growing in Spanish soils

The aim of this work is to describe the diversity and phylogeny of rhizobial bacteria associated to nodules of Ononis tridentata L. in different geographical regions of Spain. Twenty-two bacterial isolates were characterized using several molecular techniques (16S amplified ribosomal deoxyribonucleic acid restriction analysis, fingerprinting, and sequencing) and phylogenies were inferred from their 16S and nodC gene sequences. Phylogenetically, the isolates grouped with the genera Rhizobium, Mesorhizobium, Phylobacterium, and Bosea. The nodC gene, essential for nodulation, was detected for the first time in isolates close to the genera Bosea and Phyllobacterium. The bacteria isolated showed a high diversity at the genus, species, and strain level regardless of the geographical origin of the host plant. This is the first report describing bacteria associated to nodules of O. tridentata. This shrub legume is highly prized for the revegetation of gypsum soils in semiarid Mediterranean areas. Our molecular description of bacteria associated to this legume improves the current understanding of the ecology of this plant species. Our findings have implications for formulating suitable bacterial inocula to recover gypsum ecosystems.

Polyphasic Characterisation of Burkholderia cepacia-Like Isolates Leading to the Emended Description of Burkholderia pyrrocinia

Twenty-five Burkholderia cepacia-like isolates of human and environmental origin, comprising five different recA RFLP types, were examined by using a polyphasic taxonomic approach, including recA gene sequence analysis, 16S rRNA gene sequence analysis, DNA:DNA hybridisation studies, tDNA-PCR, fatty acid analysis and biochemical analysis. The results of the present study demonstrated that twenty-three of these strains belong to Burkholderia pyrrocinia, a B. cepacia complex species thus far comprising one single soil isolate only. An emended description of Burkholderia pyrrocinia is proposed. The taxonomic status of the remaining two isolates requires further analysis.