Identification of bacteria infecting Ixodes ricinus ticks by 16S rDNA amplification and denaturing gradient gel electrophoresis.

Ticks harbor a complex microbial population, which they acquire while feeding on a variety of mammalians and birds. Zoonotic diseases transferred by ticks are an increasing problem and have become a burden to the community. 16S rDNA amplification and denaturing gradient gel electrophoresis (DGGE) enables detection of the broad spectrum of bacteria that settles in the ticks. Profiling the complete microbial population in ticks may provide a better understanding of the ticks' potential to harbor and disperse pathogens. Separation of pathogenic species by DGGE is based on variation in %GC content within the 16S rDNA genetic region. Sequencing of these fragments allows identification of bacterial species. Present study identified some well-known tick-infecting bacteria, such as members of genus Borrelia, Rickettsiales, and Pseudomonas, but also less described tick-infecting bacteria such as Rhodococcus erythropolis, Spiroplasma spp., and an endosymbiont of the microarthropod Folsomia candida. This is the first report of Segniliparus rugosus-infected Ixodes ricinus ticks. Also, it is the first report of several of these pathogens in the Norwegian tick population.