Hidden Gems in the Microbiome: Newly Discovered Gut Bacteria Found to Benefit Obesity, Metabolism, and Mitochondrial Health

Despite the leaps and bounds microbiome research has made over the past two decades, we’re still just scratching the surface when it comes to knowing how exactly the ecosystem of bacteria in our guts impacts health. With up to 70% of human gut microbes yet to be identified, this “microbial dark matter” is of much interest to those researching the link between gut bacteria and disease outcomes. Similar to how the California panners of the Gold Rush sifted for the precious metal, or how modern paleontologists dig to unearth prehistoric fossils, mining the gut for new bacteria can be considered the equivalent of microbial treasure hunting.  

One bacterial treasure-hunting group based out of UCLouvain in Belgium recently hit the jackpot — not only did they discover a new bacteria, but they also named it, cultured it in a lab, and uncovered its clinical relevance to human health. Authored by Le Roy and colleagues and published in the BMJ’s journal Gut, this groundbreaking study shows how this novel gut bacteria, Dysosmobacter welbionis, benefits health, from obesity to metabolism to mitochondrial function — the energy-producing powerhouses of our cells.

Going on a Microbial Treasure Hunt 

Although it was once thought to solely play a role in digesting food and synthesizing specific vitamins, recent research has exploded with new insights into how the 100 trillion microbes in our guts affect human health. Every organ or system in the body is affected by the ecosystem of these minuscule organisms that we carry with us.

Despite this growing knowledge, researchers still have not mapped out all of the bacterial species in our gastrointestinal tracts. This is partly because microbial research is no easy feat — even after a new gut microbe is identified, the work doesn’t stop there. The researchers must then grow the bacteria in lab cultures to see what they eat, how they interact, and what byproducts they produce. Then, they test that pure lab-grown sample on humans or animals to determine its effect in clinical applications — be it helpful or harmful. 

The Belgian-based research team aimed to do just that — although they didn’t set out to find this specific bacteria. Instead, they cast a wider net, sequencing microbial data from 11,984 people across the world and finding that, unexpectedly, one type of bacteria came up over and over again, with presence in up to 70% of healthy adults. The Belgian team named their find Dysosmobacter welbionis (D. welbionis) — combining the Greek words for “smells bad” and “bacteria” with WELBIO, the life science and biotechnology organization that funded this research. As senior author Patrice Cani remarks of their hidden gem of a discovery, "That's the fun of research: you dig for dinosaur bones and you end up finding a treasure."

Healthy Humans Get a Well-Being Boost from D. Welbionis

In addition to unearthing the high prevalence of this novel gut bacteria, the research team finds that the abundance of D. welbionis differs between metabolically healthy and unhealthy people. As only a handful of bacterial species have been linked to metabolic disorders, like obesity and type 2 diabetes, the discovery of D. welbionis could have wide-reaching effects if the bacteria is used in clinical or pharmaceutical settings. 

In a sample of overweight or obese people in this study, higher D. welbionis abundance in the gut was linked to reductions in body mass index (BMI), fasting blood sugar, and hemoglobin A1C — a diagnostic marker of type 2 diabetes. These results suggest that the Dysosmobacter genus may be protective against obesity and glucose-related metabolic alterations, which are increasingly prevalent worldwide.

Microbe Mitigates Metabolic Malfunction in Mice

Although some bacterial species have been correlated with obesity and cardiometabolic disorders like heart disease and type 2 diabetes in the past, the vast majority have never been cultured or analyzed in a clinical setting. Le Roy and colleagues aimed to do just that, by testing the effects of administering D. welbionis to mice. 

Mice fed a high-fat diet developed obesity, poor glucose control, and metabolic dysregulation, all of which was mitigated by a 6-week supplementation of live cultures of D. welbionis via oral gavage, or a type of tube feeding for animals. These mice experienced partial protection against diet-induced obesity and fat mass gain, and showed improved glucose tolerance and lower insulin resistance — all of which would reduce the risk of type 2 diabetes. 

The addition of D. welbionis also changed the type of fat present in the mice. White adipose tissue (WAT) is the unhealthier type of fat, while brown adipose tissue (BAT) is metabolically active, increases energy expenditure, and reduces the risk of obesity. The mice who received D. welbionis showed a reduction in WAT cell size and count, with an increase in cell count and mitochondrial activity in their BAT cells. From these results, the researchers speculate that the modulation of WAT to BAT is likely the driver behind D. welbionis’s improvements to obesity and metabolic health.

While increasing the treatment duration from 6 weeks to 13 weeks amplified the beneficial effects to obesity and metabolism, pasteurization of the bacteria abolished its impact — meaning, D. welbionis would need to be administered in its living state to benefit human health. Lastly, after looking at the mice’s microbiome as a whole, the research team found only minor shifts in their bacterial compositions after administering D. welbionis, suggesting that the bacterium acts directly on the host metabolism, rather than changing the microbial ecosystem. 

Can This Novel Bacteria Fight Obesity in Humans?

This study strongly supports the notion that the newly discovered Dysosmobacter welbionis bacteria benefits body weight and metabolism in response to high-fat diets. As D. welbionis is more abundant in people with lower body weights and better blood sugar control, supplementation with this bacteria could be a valuable intervention for targeting obesity and other metabolic disorders. However, we don’t yet know for sure if humans would benefit in the same way as these mice did.  

As Le Roy and colleagues conclude, “Altogether, our data strongly support the beneficial effects of live D. welbionis on diet-induced obesity and diabetes. These findings suggest that [D. welbionis] is a next-generation beneficial bacterium that should be investigated in other clinical paradigms than obesity and diabetes...and should be tested in humans for its positive effects on host metabolism.”

References:    

Le Roy T, Moens de Hase E, Van Hul M, et al. Dysosmobacter welbionis is a newly isolated human commensal bacterium preventing diet-induced obesity and metabolic disorders in mice [published online ahead of print, 2021 Jun 8]. Gut. 2021;gutjnl-2020-323778. doi:10.1136/gutjnl-2020-323778