New study explains why diverse gut microbiomes offer better protection against harmful microbes

In the last decade, it has become increasingly clear that a gut full of friendly microbes (the microbiome) is vital for our good health. It has also become clear that a healthy microbiome is one with a diverse population of microbes (bacteria, viruses, fungi). What we haven’t known is why a diverse array of friendly bugs is important for keeping the harmful microbes (pathogens) at bay. But now we think we have found the answer.

Our latest study, published in Science, shows that the main reason a diverse microbiome is helpful for resisting pathogens is that the friendly microbes collectively consume the nutrients needed for a pathogen to grow in the gut.

In other words, a diverse microbiome blocks pathogen growth by using its nutrients – a phenomenon we call “nutrient blocking”. Understanding how nutrient blocking works is powerful because it allows us to predict which gut communities will be protective against a given pathogen.

Our research team started by conducting a large screen of 100 common strains of human gut bacteria. We tested the individual ability of these strains to restrict the growth of two bacterial pathogens, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium. These two species are a problem because many strains are becoming resistant to antibiotics.

Nutrient use

Alone, the gut strains could not...

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