Microbes are everywhere: in the soil, on rocks, in and on us, animals, plants, etc. In science and medicine this is not a secret. But what is less well known is that these microbes often live in a particular way, inside a gel and attached to a surface. This particular way of living is called a biofilm, and it can be seen as a fortress that makes its inhabitants more resistant, organised and productive than microbes that live freely in the air or water.
"Biofilms are, in fact, cities of microbes composed of hundreds or thousands of species that are in complex interactions," tells Hugo Sentenac, "They are forming their own tiny ecosystem, embedded in a much larger ecosystem such as a lake".
In fact, these tiny biofilm ecosystems are matrix-enclosed communities that represent the most dominant and active mode of microbial life on Earth. Because biofilms are inherently more productive than any equivalent planktonic community, they are of great relevance to all environments they inhabit. The existence and importance of biofilms, however, largely escapes the general public, but also conservation practitioners and environmental policymakers.
Why would that be of any importance? Why should we care about tiny biofilm ecosystems? Why should policymakers and conservationist care?
Biofilms can have negative and positive roles, depending on the context. But overall, biofilms are important for our health: for instance, the microbes that live in our gut are vital for our growth and the normal functioning of our bodies and those of animals and plants. A balanced and diverse biofilm protects us from diseases such as obesity, autism or cancer and even from infectious diseases. Biofilms in the environment are also essential not only for the normal functioning of ecosystems.
Dirk Schmeller adds: "They provide oxygen and food for many organisms by using solar energy as plants do".
Biofilms also contribute to ecosystem health and hence indirectly to human health, by biodegrading pollutants in water and soil, limiting erosion and ensuring soil fertility, among many, many other things. However, environmental biofilms can promote the persistence of human pathogens, produce harmful toxins, foul and corrode surfaces in natural and man-made settings; all of which can have significant health and economic implications. All this is important to understand and has major implications on decision making. Despite this important there is a knowledge gap about the roles of biofilms in the epidemiology of wildlife emerging infectious diseases, yet these pose a major threat to public health, biodiversity and sustainability. The drivers of global environmental change all affect biofilm structure and functions. The consequences for host and ecosystem health are, however, poorly understood.
Hugo Sentenac concludes: "While the concept of a healthy microbiome is emerging in medicine and conservation biology, the concept of a healthy biofilm remains to be defined in environmental sciences."
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