Ribosomal DNA fragments analysis of avian pathogenic Macrorhabdus ornithogaster

Macrorhabdus (M.) ornithogaster is a common cause of fungal gastric disease in passerines and psittacines held in captivity as well as in free-range birds with a worldwide distribution. However, despite culturing of M. ornithogaster is standardized since nearly 10 years now, only three nucleotide sequences isolated from two bird species are currently available in GenBank (http://www.ncbi.nlm. nih.gov) referencing ribosomal DNA fragments. Therefore, the aim of this study was to gain knowledge on the occurrence of different genotypes within specific bird species as well as to optimize molecular biological characterization of this common avian pathogenic yeast. Isolates (n = 15) were obtained from nine individuals belonging to five bird species. Samples of the proventricular isthmus as well as isolates gained after culturing of content from proventricular isthmus have been amplified and sequenced. Successful amplification and sequencing of M. ornithogaster-specific small subunit ribosomal DNA (SSU), ITS-1 gene and the first part of the large ribosomal DNA (D1/D2) was possible in almost all isolates and samples. However, use of cultured isolates is preferable in order to avoid or at least to identify contamination. According to the present gene sequence analysis, M. ornithogaster represents genomic variability inside the ribosomal genome. Further phylogenetic studies are needed to clarify the epidemiological impact of this variability.