Characterization of the bacterial community on the feathers of wild dark-eyed juncos (Junco hyemalis)

Abstract

Wild birds rely on plumage for protection, reproductive display, and flight. Alterations to feather structure or color by symbiotic microbes may reduce survival and reproductive fitness. Feathers are waxy oligotrophic environments low in moisture and rich in recalcitrant beta-keratin subject to freezing temperatures and high UV radiation. Ventral feathers were sterilely collected from wild dark-eyed juncos (Junco hyemalis) by mist net capture and shaken in a chaotropic solution to dislodge bacterial cells. More than 300 bacterial isolates, mainly Gram-positive cocci and bacilli, were collected by serial dilution of enrichment cultures and purified by repetitive streaking on agar plates to generate an isolate collection. Isolates were tested for their ability to degrade keratin, the principle component of feathers, as well as other biochemical tests. Approximately half of the isolates were able to grow on keratin as a sole carbon and energy source. Surveys of bird feather samples were also tested for their ability to establish colonies under conditions mimicking environmental stressors such as desiccation and temperature extremes. Phylogenetic analysis of PCR-amplified 16S rRNA gene sequences from the isolate collection showed substantial bacterial diversity including representatives of the genera Bacillus, Rhizobium, Staphylococcus, Pseudomonas and Sphingomonas. Supported by NSF GK-12 and NIH KINBRE P20GM103418.