How has urbanisation impacted microbial biodiversity, human health and urban ecosystem services?

Urban landscapes are now the dominant living environment for humanity. These urban environments offer myriad social, cultural and economic benefits to human health which often results in better health metrics compared to rural counterparts. However, they separate people from biodiverse nature which is known to have important health benefits for people. Cities also alter the microbial (e.g. bacterial, fungal) communities to which people are exposed: with potentially important but underexplored health impacts. In particular, higher rates of asthma and allergies has been linked to exposure to less diverse microbial communities. But microbial studies in urban areas present conflicting results on the effect of urbanisation on environmental microbiomes; some studies have found urban microbiomes to be less diverse, others have found greater diversity than environmental microbiomes in rural and natural environments. Understanding the effect of urbanisation on microbial diversity is important both for human health and ecosystem functioning. Here we present evidence from a global systematic review exploring the impact of urbanisation on airborne microbiomes and recent local evidence of the effect of urbanisation on the environmental microbiomes in Hobart, Tasmania. We discuss how these changes represent a compromising of ecosystem services in cities. While there are similarities between the patterns in Hobart and the global patterns, this presentation highlights important differences that need to be explored to better understand urban health. We propose how closing this knowledge gap could be applied to improve urban biodiversity, ecosystem services and the health of urban populations.