Dancing with the Dust Devil: Examining the Lung Mycobiome of Sonoran Desert Wild Mammals and the Effect of Coccidioides Presence

Microbiome studies report a decrease in diversity associated with active infections. Under the endozoan hypothesis, Coccidioides can inhabit a host without causing disease. In this study, we describe and compare the lung mycobiome of Coccidioides-positive and -negative samples obtained from wildlife. If Coccidioides is not causing infection, we predict there will be no differences in the mycobiome between positive and negative samples. Lung samples were obtained from mammals previously trapped in Tucson, Arizona, USA (n = 26), and Mesa, Arizona, USA (n = 14). Samples were screened for Coccidioides with CocciDx, and mycobiome was characterized through Illumina-based amplicon sequencing of the internal transcribed spacer 2 (ITS2). We compared alpha and beta diversity of the mycobiome to assess the effects of Coccidioides’ presence and host taxonomy. A greater number of reads were captured from Tucson samples (114,706.4 ± 57,945.8) than from Mesa (384.9 ± 953.5); however, Mesa (16.8 ± 8.8) and Tucson (12 ± 7.8) had a similar number of fungal genera per sample. CocciDx detected Coccidioides in more samples than the ITS2 amplicon sequencing. All samples from Mesa and five from Tucson tested positive for Coccidioides. Therefore, Mesa samples were excluded from statistical analysis. No difference in alpha and beta diversity was associated with Coccidioides presence, which is consistent with the endozoan hypothesis. Host taxonomy had a significant effect on beta diversity. This effect is likely driven by host behavioral and physiological differences.