The jungle within us

“Biodiversity”, “predators” and “native species” are words normally associated with a National Geographic documentary featuring a dense jungle or rainforest. However, these words are just as important in describing the specialised ecosystem of the human gut. Indeed, the microbiome can be considered a microscopic jungle carried around within every individual human being. Each little jungle consists of an array of native species, predators, prey and in total around 100 TRILLION different organisms including bacteria, viruses, fungi and protozoa. Still, every microbiome is unique.

Just like the jungle, it is a dynamic and complex ecosystem with myriad interactions within it and with the world it is contained in (us). Survival of the fittest and the laws of the jungle prevail. Bacteria compete with each other to establish their populations and based on the available resources, certain species thrive while others may die out. This generally depends on our diets because when we feed ourselves, what we are really doing is feeding our microbiome. If a particular species likes what we are eating, it will thrive and even send feedback to our brains to eat more of that. Eating diverse foods is therefore a good way to maintain ecological diversity in the gut-forest.

Meanwhile, the bacteria themselves have predators. The most abundant inhabitants of the micro-jungle, yet the most elusive, are the bacteriophages. The viruses that invade and kill residing bacteria have a vital role to play in maintaining the balance of the ecosystem. Colin Hill recently spoke at Groningen’s ERIBA molecular medicine seminar highlighting how little we know and how much there is to discover about these “predators”. While the general species of bacteria inhabiting the gut varies may vary amongst populations to some extent, we have a fair idea of the major strains and share a wide number of them. However, the phageome tends to be more unique to an individual and can tell more about the history of the bacteria that used to live in that environment.

Now imagine taking a broad spectrum antibiotic. This is akin to carrying out large scale logging or deforestation in this precarious ecosystem. The jungle species must evolve and cope with the damage. The fungi may have a field day, but the phage have lost most of their prey. The disruption affects not only the local environment but that of the other ecosystems within the body. However, phage do act as genetic reservoirs, and they need their food. It is possible that the phage could confer antibiotic resistance to their prey, just so that they can “cultivate” more infectable hosts and continue surviving themselves. Either way, bacteria manage to survive and to resist the onslaught the next time around.

As with saving the Amazon jungle, we need to now turn towards preventing these large scale deforestations that have gotten us into the trouble we are in. Understanding bacteriophages can help us create new, targeted antibiotics that can help eradicate the “invasive species” of our micro-jungles without destroying the entire ecosystem. So let’s save the trees and save our (good) B(acteria)s.

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