By Francesca Ceroni

William Gilbert once said that “we are embedded in a biological world and related to the organisms around us”. This is very true especially if we think about the many bacteria and microorganisms that co-exist within our body and that we do not always notice, except when their presence leads to an infection or disease. A special case of symbiosis is the one between us and the gut microbiome, as we define the totality of bacteria, viruses and eukaryotes living in our gastrointestinal tract right now, even as you read this article.

The composition of the gut microbiome is different from person to person and the microorganisms composing it are responsible for a myriad of functions that are directly linked to our life and wellbeing. Nutrient absorption, production of important vitamins and metabolites, immune cell stimulation, are just a few of the roles of the microbiome that we benefit from. When the bacteria living in gut are imbalanced or some of the species normally present become under-represented, we can suffer from a medical condition known as dysbiosis.

In recent years, several studies have highlighted the role of the gut microbiome in a broad range of neurological and psychiatric disorders. In 2019 researchers from the University of Leuven reported, e.g., that specific bacteria in the human gut release neurotransmitters that have a direct impact on our mental quality of life and depression¹. In 2007 The Human Microbiome Project was launched to study and characterise the microbial communities present in and on our body and to better understand their role in ensuring our health or in causing disease². Over the last years, genetic engineering has also looked at microbiome engineering with great interest and a number of engineered bacterial systems are already in clinical trials, trying to exploit the presence of gut bacteria for the treatment of diseases³.

These studies and applications once more bring to evidence that our own life is the result of a tightly controlled and balanced network of interactions and that we too are the result of hidden relations that embed us.

References

1. Valles-Colomer, M., Falony, G., Darzi, Y. et al. The neuroactive potential of the human gut microbiota in quality of life and depression. Nat Microbiol 4, 623–632 (2019).
2. Turnbaugh, P., Ley, R., Hamady, M. et al. The Human Microbiome Project. Nature 449, 804–810 (2007)
3. Tan X, Letendre JH, Collins JJ, Wong WW. Synthetic biology in the clinic: engineering vaccines, diagnostics, and therapeutics. Cell. 2021 Feb 18;184(4):881-898

Francesca Ceroni is a Lecturer in the Department of Chemical Engineering and a member of the Imperial College Centre for Synthetic Biology at Imperial College London, UK.