How urban nature boosts your microbiome

A walk in the park does more than just clear your head. Researchers at the University of Antwerp are studying how microorganisms from urban nature colonise our bodies — and likely strengthen our immune system.

We wash our hands, disinfect surfaces and live increasingly sterile lives — but this does not always prove advantageous. ‘People need to be exposed to natural microorganisms in order to strengthen their immune systems properly,’ observes Irina Spacova (Department of Bioscience Engineering, Faculty of Science). ‘Amongst those who have much less contact with microbes found in nature – such as city children – we see more allergies, asthma and inflammatory diseases.’

Initial findings suggest that park visitors ingest quite a lot of microorganisms. ‘On average, 7% of the hand microbiome consisted of park bacteria after a visit,’ reports Santullo. ‘For some participants, this figure rose to 12%.’

The changes in the nasal microbiome are less pronounced, as hands come into more direct contact with the environment. The researchers have also observed differences depending on what people do in the park. Santullo explains, ‘Climbing trees or playing in the bushes leads to more transmission than playing football or something like that.’

The bacteria identified include such species as Sphingomonas (commonly found on plant leaves) and Streptomyces, a group of bacteria that produce natural antibiotics.

A stronger immune system

In the lab, the scientists are also investigating whether — and exactly how — this transfer yields measurable health benefits. Their work includes trying to cultivate the species recovered in the samples and test them on human cells.

There have long been strong indications that contact with biodiversity is important. Spacova refers to a Finnish study in which researchers enriched sandpits at childcare centres with forest soil. ‘After a month, they observed not only changes in the children’s skin microbiome, but also an immune profile less prone to inflammation — meaning that the children were falling ill less often.’

Healthier urban green spaces

According to the researchers, it is important to realise that green spaces are much more than simply places to relax. ‘We want to understand how we can design and maintain parks to be as microbiologically healthy as possible,’ Santullo notes. ‘By involving many members of the public — including young children — in our research, we hope to raise awareness of the importance of healthy and accessible green spaces in the city.’