Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2019

Transfer of Environmental Microbes to Humans in Urban Green Space Environments (#191)

Caitlin A. Selway 1 , Jacob G. Mills 2 , Philip Weinstein 2 , Andrew Lowe 2 , Martin F. Breed 2 , Laura S. Weyrich 1
  1. Australian Centre for Ancient DNA, University of Adelaide, Adelaide, SA, Australia
  2. School of Biological Sciences and the Environment Institute, University of Adelaide, Adelaide, SA, Australia

Urbanisation has significantly changed human lifestyles with increases in population density, pollution exposure, and incidences of immune diseases. In parallel, there has been a decrease in green space environments and their microbial diversity. Decreased human microbial diversity is linked to immune diseases, which have increased worldwide in the past 50 years within urban areas. There are several hypotheses on microbial exposure (e.g. Hygiene, Old Friends and Biodiversity hypotheses) that describe urban populations as ‘too clean’ and that these populations are no longer exposed to diverse environmental microbiota and microbial stimulants. These exposure factors likely alter and disrupt immune priming, and therefore contribute to the development of immune diseases. The Microbiome Rewilding Hypothesis proposes to decrease the prevalence of immune diseases observed today by increasing human-associated microbial diversity through urban biodiversity restoration. However, the microbial interaction between humans and their surrounding environment is not well understood. Here, we present the diversity and taxonomic profiles of microbes transferred from urban green space environments to the skin and respiratory tract of two individuals. Using a 16S rRNA metabarcoding approach, we analysed skin (n=90) and nasal (n=90) swabs collected from urban green spaces within Australia, the United Kingdom, and India, as well as air (n=30), soil (n=15), and leaf (n=15) samples from Australia. Morning controls of both skin (n=16) and nasal (n=16) swabs were collected allowing for before- and after-exposure comparisons. We found increased microbial richness and phylogenetic diversity after green space exposure in skin and nasal samples for all three countries. Beta-diversity showed that skin swabs became more similar to the microbiota of soil and leaf samples, while nasal swabs became more similar to microbes found in air samples. Interestingly, the nasal swabs from India were distinctly different from all other samples and contained less overall microbial diversity. Overall, this study improves our understanding of human-environmental microbial interactions and suggests that exposure to these environments may lead to positive outcomes for immune diseases.