Postbiotic Foods and Drinks that Carry Dead Gut Microbes May Be More Important Than Prebiotics, Say Scientists

The complex web of interactions between gut microorganisms and our health has been further unraveled, thanks to a study led by RIKEN scientists. This team delved into how one particular gut bacterium leads to a reduced lifespan in fruit flies, thereby adding a new dimension to our understanding of the human gut, which is a host to hundreds of bacterial species.

While a significant number of these bacteria are beneficial, aiding in the conversion of food into substances the human body can’t produce itself, there are some species that can be detrimental to our health.

The challenge lies in determining the individual effects of these countless species on our health, hence why scientists often turn to study the much simpler gut microbiome of fruit flies, which only harbors two to five bacterial species.

Fumiaki Obata from RIKEN Center for Biosystems Dynamics Research, in his earlier work, had observed that Acetobacter persici, a particular species, was linked to accelerated aging in flies, resulting in early death.

“A. persici has a drastic impact on fly lifespan, curtailing it by about 20%–30%,” Obata explains. However, the mechanism behind this significant impact was hitherto unknown.

In a recent study published in PLOS Genetics, Obata and his colleagues found the missing link by examining flies that were fed on a diet of dead A. persici. They discovered that a component of A. persici’s cell wall activates a receptor in the fly’s gut.

This activation stimulates the immune system, resulting in an overproduction of antimicrobial substances and a boost in intestinal stem cell activity, which eventually leads to premature death.

Interestingly, they found that the enhanced immunity also enhances the flies’ resistance against infections from harmful bacteria that can be lethal, offering them a short-lived advantage at the cost of early death.

This “live fast, die young” trade-off theory explains why many wild flies carry A. persici or similar Acetobacter species in their guts.

“This increased resistance to infection explains why the vast majority of flies in the wild have A. persici or other Acetobacter species in their guts,” notes Obata. “It’s better to have a strong resistance to stressors such as infection rather than to live to a ripe old age.”

The discovery suggests that “postbiotics”—foods and beverages that contain dead gut microbes (as opposed to prebiotics, which includes living ones)—could be produced and have positive health effects.

The next step for the team includes identifying the genes responsible for the immune response that shortens lifespan.

Additionally, they aim to explore if this mechanism is present in other species such as mice and humans.

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