First first-authorship paper accepted for Olivia Choi from the Kamath Lab!

Olivia Choi, a doctoral candidate in the Kamath lab at the University of Maine, has had her first scientific paper accepted for which she is the first author – a position indicative of the amount of work and organization that she put into developing this work and wrangling the large research team involved. Olivia’s graduate work is winding down as she concentrates on writing up papers and her dissertation, and she is planning on defending her PhD and looking for a postdoc in 2022 in wild animal microbiomes and ecology.

Olivia brought this 16S rRNA dataset to use in my AVS590 data analysis class back in spring 2020, of bacterial communities in different locations on birds of different species, which had been sampled as part of her dissertation work on bird migration and range changes, microbial carriage, and risk of transmission of microbes to other animals. I mentored her through analysis and preliminary manuscript writing as part of that course. The research team generously invited me to join the author team, and I continued to provide mentorship as Olivia worked through the complex task of melding various types of microbiology data.

Choi, O., Corl, A., Lublin, A., Ishaq, S.L., Charter, M., Pekarsky, S., Thie, N., Tsalyuk, M., Turmejan, S., Wolfenden, A., Bowie, R.C.K., Nathan, R., Getz, W.M., Kamath, P.L. 2021. High-throughput sequencing for examining Salmonella prevalence and pathogen – microbiota relationships in barn swallows. Frontiers in Ecology and Evolution 9:681.


Studies in both humans and model organisms suggest that the microbiome may play a significant role in host health, including digestion and immune function. Microbiota can offer protection from exogenous pathogens through colonization resistance, but microbial dysbiosis in the gastrointestinal tract can decrease resistance and is associated with pathogenesis. Little is known about the effects of potential pathogens, such as Salmonella, on the microbiome in wildlife, which are known to play an important role in disease transmission. Recent studies have expanded the traditional use of 16S rRNA gene amplicon data from high-level characterization of host-associated microbial communities (i.e., the microbiome) to detection of specific bacteria. Few studies, however, have evaluated the ability of high-throughput 16S rRNA gene sequencing data to detect potential bacterial pathogens in comparison with laboratory culture-based methods. To address this knowledge gap, we evaluated the utility of 16S rRNA gene sequencing for potential pathogen detection and explored the relationship between potential pathogens and microbiota. First, we compared the detection of Salmonella spp. in barn swallows (Hirundo rustica) using 16S rRNA data with standard culture techniques. Second, we examined the prevalence of Salmonella using 16S rRNA data and examined the relationship between Salmonella presence or absence and individual host factors. Lastly, we evaluated host-associated bacterial diversity and community composition in Salmonella present versus absent birds. Out of 108 samples, we detected Salmonella in 6 (5.6%), 25 (23.1%), and 3 (2.8%) samples based on culture, unrarefied 16S rRNA gene sequencing data, and both techniques, respectively. In addition, we found that Salmonella presence and absence differed between birds based on migratory status and weight and that bacterial community composition and diversity differed between Salmonella present versus absent birds, with eleven bacterial taxa differentially abundant between the two groups. The results of this study highlight the value of high-throughput 16S rRNA gene sequencing data for bacterial pathogen detection and for examining relationships between potential pathogens and host-associated microbial communities. Further, this study emphasizes an approach using 16S rRNA gene sequencing data for simultaneously monitoring multiple pathogens in wild avian reservoirs, which is important for prediction and mitigation of disease spillover into livestock and humans. 

This work was presented at a recent scientific conference:

Choi*, O.N., Corl, A., Wolfenden, A., Lublin, A., Ishaq, S.L., Turjeman, S., Getz, W.M., Nathan, R., Bowie, R.C.K., Kamath, P.L. “High-throughput sequencing for examining Salmonella prevalence and pathogen -microbiota relationships in barn swallows.”  69th Annual – 14th Biennial Joint Conference of the Wildlife Disease Association & European Wildlife Disease Association. (virtual). Aug 31 – Sept 2, 2021.

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