Microbes, while small in size, play a huge role in our lives. They are an important part of biogeochemical cycles, they can help mitigate environmental pollution and they may even be an invaluable resource for space exploration. They may also be the key to reducing human diseases.
Humans evolved along side a rich array of microbes and for the past ten-thousand years we have increasingly moved away from nature and into anthropogenic built-up environments that continue to decrease our exposure to microbes. The more time humans spend indoors, the greater the imbalance between humans and microbiota occurs leading to dysbiosis.
For the past hundred years non-communicable human diseases have been on the rise. Incidences of cancer, autoimmune disorders, and mental illness continue to increase despite advances in science and technology. These illnesses may be linked to a lack of exposure to a diverse population of microbes. Many people in developed countries have traded agrarian lifestyles for urban settings. Compared to rural settings, these urban concrete jungles have very few areas set aside for outdoor recreation where people can encounter plants, soil, and most importantly, a wide array of microbes. When these green spaces are available, many have been heavily treated with herbicides, insecticides, and other chemicals which reduce the diversity of all organisms including microbes. Research has suggested that contact with a variety of microbes, particularly those found in soil, are essential for helping to develop a strong immune system. Additional studies have indicated that faulty immunoregulation, from a lack of exposure to diverse microbes, may also be responsible for increased inflammation. Chronic inflammation has been linked to certain neurological disorders, cardiovascular disease, and other non-communicable human diseases. Evidence indicates that these types of diseases are increasing in high-income countries suggesting that urban environments, despite all of their luxuries and amenities, may be contributing to the decline in human health.
Image 1. Various diseases impacted by human microbiota dysbiosis
Image from https://www.nature.com/articles/s41392-022-00974-4
There may be a way to combine urban living and environments that support microbial diversity in a way that will benefit the health of people young, old and in between. Embracing Microbiome-Inspired Green Infrastructure (MIGI) may be one way to counterbalance the microbe dysbiosis that occurs in urban settings. By undertaking urban revitalization in areas already devoid of most green spaces, city planners can coordinate with engineers and developers to construct areas where plant, animal, and microbial life can thrive while also providing people meaningful interaction within these environments.
Image 2. Microbial-Inspired Green Infrastructure of the Future.
Image from https://www.mdpi.com/2076-2607/10/12/2311
Microbial-Inspired Green Infrastructure goes beyond creating city parks and aesthetic landscaping. It also encompasses incorporating microbe centered design into current buildings, businesses, and residential areas. Some examples include adding nature areas to schools, providing gardening areas and supplies for apartment dwellings, and adding live plants to hospital settings.
Day-cares and primary schools in urban areas could be designed to have nature areas, untouched by chemicals, where children are encouraged to interact with the soil and plants. Research has indicated that when children in urban areas come into contact with soil teeming with a vast array of microbes, the immunoregulatory pathways of their immune system improve.
Apartment dwellings have limited access to outdoor spaces when compared to those who live in stand-alone houses. Those who live in houses have better access to outdoor spaces compared to those who live in apartment complexes, so it may be challenging to find ways to increase the access of apartment dwellers to beneficial microbes. These challenges could be tackled in a number of ways including adding rooftop gardens to apartment building rooftops, providing residents with small indoor gardening plants, and adding raised garden and/or flower beds to courtyards.
Hospitals could also incorporate microbe centered design and practices to help improve the health of its patients and staff. Research suggests that having a diverse variety of microorganisms in a hospital setting may help reduce the numbers of human pathogenic organisms present in the environment. While some areas of the hospital need to be microbe-free, other areas could incorporate beneficial microbes by adding green plants and through the use of Bacillus probiotic-based sanitation methods.
Research has pointed to the correlation between reduced exposure to diverse microbes and increased rates of non-communicable diseases in humans, and it is believed that urban city-scapes are to blame for causing this dysbiosis. However, this trend does not have to continue. There are changes we can make to our urban environments to increase the variety of microbes we encounter. By using the microbial-inspired techniques and practices discussed here we have the opportunity to improve our urban infrastructure in a way that will improve our own health while protecting the health of future generations.