Onygenalean fungi detected in Martes zibellina by culturomics and NGS approaches
The aim of the study was to detect potentially pathogenic fungi in skin lesions of wild sables Martes zibellina from Siberia region of Russia. Outbreaks of mass skin lesions in Siberian sables are known for decades, but their true etiology is still unknown. To reveal the possible etiological role of fungi, 15 samples from affected skins were submitted for conventional mycological investigation, and three of these samples were subjected to next-generation sequencing (NGS) targeting the internal transcribed spacer (ITS) region on Illumina MiSeq instrument. Of 3 samples, only one yielded sufficient quantity of fungal DNA to perform NGS analysis. Totally, 34810 assigned sequences and 249 operational taxonomic units (OTU) were yielded from the sample by NGS. Of them, 9% OTU belonged to order Onygenales. In Onygenales, Arthrodermataceae fraction was 18%, incertae sedis families – 81%, Ajelomicetaceae – 0,5% and unidentified family – 0,5%. In Arthrodermataceae, genus Arthroderma was presented by species A. insingulare. Genus Trichophyton consisted of T. onychocola and Trichophyton spp. Interestingly, this Trichophyton spp. was closely related to Arthroderma cuniculi (93,5% ITS homology revealed by BLAST). In incertae sedis families, genus Chrysosporium (i.s.) was dominated and included C. carmichaelii, C. undulatum and Chrysosporium spp. (unidentified). Genus Malbranchea was minor and presented by M. cinnamomea only. Ajelomicetaceae was presented by Emmonsia genus, which consisted of E. helica only, the possible agent of adiaspiromycosis. On cultural study 31 fungal isolates were obtained, 3 of them belonged to Onygenales (9,6%). Two of them were presumably identified as Arthroderma cuniculi (GenBank accessions MN534766.1 and MN653980.1) and third as Chrysosporium carmichaelii (GenBank accession MT556012.1). Each of Onygenalean fungi was isolated from different skin samples, and no Onygenales representatives were isolated from NGS-processed sample. In conclusion, a range of keratinophilic fungi belonging to Onygenales were detected in affected wild sables, thus showing probable fungal etiology in mentioned mass skin disease. The NGS revealed that up to six keratinophilic species can be found in the same animal. Wherein, only two of them were detected by conventional cultural analysis. Pathogenic properties of detected Onygenalean fungi should be estimated in successive studies.