The human gut may help control the bacterial populations that live within it via secretions that kill some bacteria while supporting others, according to a study published Tuesday in the journal PLoS Biology.
The gut is an enormously complex environment inhabited not only by human cells but also by trillions of bacteria. Some of those bacteria actively aid us by improving digestion (hence the term "probiotic"), producing useful compounds like vitamins, or providing resistance against pathogens.
But many if not most probably do little at all to benefit humans, instead mooching off the gut's nutrient-rich environment to survive without giving much back in return. And some denizens of this microbiome actually do us harm. This raises a problem for the gut: How can it support the good bacteria while discouraging the rest? Such a question is particularly vexing because bacterial strains don't all grow at the same speed, meaning that beneficial strains that grow more slowly would soon be overtaken by harmful, faster-growing bacterial colonies without a way for the body to select some species over others.
To answer that question, Jonas Schluter and Kevin Foster of Oxford University developed a computer model that replicates a simplified version of the gut. Their goal: To see whether slight differences in the gut's secretions, which have the power to aid or inhibit bacterial growth, might be able to bias the gut's environment toward beneficial strains of bacteria.