CONSTRUCTING AND COMPARING MICROBIOME NETWORKS FOR HEALTHY AND EAR MITE-INFECTED SANTA CATALINA ISLAND FOXES

Abstract

Highly prevalent in in the ear canals of Santa Catalina Island foxes (Urocyon littoralis catalinae), ceruminous gland tumors are a major health threat to this threatened species. It has been proposed that inflammation stemming from ear mite infection, coupled with secondary infection from the opportunistic pathogen Staphylococcus pseudintermedius may create conditions that promote tumor development. I analyzed a set of microbiome data collected from these foxes in 2019 in order to confirm these patterns. I found that mite infection was associated with dysbiosis in the ear canal microbial community via reduced diversity and evenness, and S. pseudintermedius once again dominated the mite-infected community. I extended on this framework by constructed networks for mite-infected and uninfected microbiomes. In the infected network, I observed that interaction strengths between taxa were generally weaker and some subnetworks otherwise found in the uninfected network disappeared altogether, suggesting that mite infection disrupts community structure. I also found that S. pseudintermedius maintained an interaction with another S. pseudintermedius strain across disease states networks, hinting at biofilm formation. Under mite-infected conditions, S. pseudintermedius did not retain an interaction with Acinetobacter rhizosphaerae, which may imply that A. rhizosphaerae was outcompeted by the dominant pathogen. Finally, the lineup of potential keystone taxa shifted across disease states, and Fusobacteria spp., a carcinogenesis-promoting microbe, appeared to take on a keystone role in the mite-infected community. Taken together, these findings from a network analysis provide us a glimpse into how mite infection may destabilize the microbiome and ultimately contribute to tumor development.