The Microbiome of the Built Environment: The Nexus for Urban Regeneration for the Cities of Tomorrow

Abstract

Built environments are, for most of us, our natural habitat. In the last 50 years, the built-up area has more than doubled, with a massive biodiversity loss. The undeniable benefits of a city providing all the basic needs to a growing population showed longer-term and less obvious costs to human health: autoimmune and non-communicable diseases, as well as antimicrobial resistance, have reached unprecedented and alarming levels. Humans coevolved with microbes, and this long-lasting alliance is affected by the loss of connection with natural environments, misuse of antibiotics, and highly sanitized environments. Our aim is to direct the focus onto the microbial communities harbored by the built environments we live in. They represent the nexus for urban regeneration, which starts from a healthy environment. Planning a city means considering, in a two-fold way, the ecosystem health and the multidimensional aspects of wellbeing, including social, cultural, and aesthetic values. The significance of this perspective is inspiring guidelines and strategies for the urban regeneration of the cities of tomorrow, exploiting the invaluable role of microbial biodiversity and the ecosystem services that it could provide to create the robust scientific knowledge that is necessary for a bioinformed design of buildings and cities for healthy and sustainable living.

Keywords: MIGI; MetaSUB; bioinformed design; built environment; hospital microbiome project; hygiene; microbiome; smart cities; sustainability; urban.

Figure 1

Urbanization timeline and scientific milestones roadmap. This schematic and not exhaustive representation covers the main milestones of urbanization (in the upper part) and the key scientific findings and projects that allowed us to gain awareness about the microbiome of the built environments (in the lower part). From ancient civilizations to nowadays, urbanization has increased enormously. Despite cities and inhabited areas having developed for thousands of years, only recent scientific advances have enabled the evaluation of the influence of urbanization on the microbiome of the built environment (BE) and human health. The end of the roadmap is projected towards the cities of tomorrow, and, in this context, the MUSA (Multilayered Urban Sustainability Action) project [29] was born. AMR: antimicrobial resistance; OLD FRIENDS HP: Old Friends Hypothesis; MetaSUB: The Metagenomics and Metadesign of the Subways and Urban Biomes.

Figure 2

The new “Urban”: Projects regarding future everyday life hot-spots is something that must be done today; in the illustration, a hand is indeed drawing the vision for a new meaning of infrastructure. The key themes are functions integration and social inclusion through bioinformed design and architecture. The same spaces have multiple functions. The park becomes a recreational (but also educational) area of a university campus underlying the imperative role of knowledge in re-modelling the environment. Public transportation lines are surrounded by trees, vegetation, and natural elements such as ponds and gardens, so that autochthonous species become reintegrated. Houses and workplaces are designed to be well-lit environments, with direct access to nature thanks to the presence of terraces and common gardens (that also favor socializing and manual activities such as gardening and horticulture). Architectural elements, such as acoustic barriers and structural walls, are implemented along with green-promoting elements. Lastly, hospitals are re-designed to promote physical and mental health via lighter and greener accessible areas, on one hand, and via the reduction in the transmission of possible pathogenic microorganisms (isolating patients from commonly touched medical equipment). The microbiota is represented as the human–health–environment linking element.

Figure 3

Rewilding today’s urban centers: While designing policies to address the construction of the integrative cities of the future, we will have to transition through an intermediate phase of nature’s inclusion in existing urban areas. This illustration is realized with clippings representing the city of today (a crowded square, clusters of skyscrapers, commuter subway lines, and the core of last year’s public health: hospitals). The figure’s layered structure represents the different tiers we must act on to renovate the current urbanization condition. On top of everything, painted vegetation is inserted in the already existing urban pattern: a call for greener living spaces is becoming increasingly essential. The microbiota (both human and environmental), represented in yellow in the background, envelops everything as the linking element between humans and the context we built and live in. Not only does our health depend on our microbiome, but its composition is heavily affected by environmental changes; just as in a collage, every piece is glued to the others.