In 1989, a microbiologist was given a diseased appendix which had been removed from a patient. From it was cultured a previously unknown bacillus, Biophila wadsworthia, which became classified as a pathobiont – a microbe which is normally symbiotic or helpful, but which has the potential to become pathogenic or disease-causing. It came to be suspected of causing inflammation, abscesses, bowel disease, and even cancer.
Now, if Postdoctoral Fellow in the Oregon State University College of Science Veronika Kivenson is correct, this bacillus may also have a previously unsuspected role in preventing cardiovascular disease. Dr. Kivenson is the lead author of “An Expanded Genetic Code Enables Trimethylamine Metabolism in Human Gut Bacteria,” published in the American Society for Microbiology’s journal mSystems.
If the findings of Dr. Kivenson’s OSU team can be replicated by others, it opens up the possibility that tailored bacterial cultures can be used in probiotic treatment, a form of medicine in which bacteria are an ally of human health, not an enemy. The study also suggests that meat may not be as bad for your arteries as previously thought.
The study indicates that Biophila plays a previously unsuspected role in human metabolism, and this misunderstanding has led to incorrect ideas about how cholesterol winds up sticking to the walls of blood vessels. Because meat is rich in trimethylamine (TMA), which the liver converts to trimethylamine-N-oxide (TMAO).
“The connection between TMAO and cardiovascular disease has tended to focus the conversation on how animal-based diets cause negative health consequences,” Dr. Kivenson told Steve Lundeberg, writing for OSU Newsroom. “But in analyzing data from foundational gut microbiome studies, we uncovered evidence that one type of bacteria associated with meat consumption can take the TMA, as well as precursors to TMA, and metabolize them without producing any TMAO. That means those bacteria are in effect severing a key link in the cardiovascular disease chain.”
Bilophila’s secret appears to be an expanded genetic code which allows them to use a demethylation pathway to metabolize TMA and release other substances instead of TMAO.
Dr. Steve Giovannoni, co-author on the study and an OSU Distinguished Professor of Microbiology, told Lundeberg, “The organisms in your stomach have been shown to affect the development of myriad disease states. But the mechanisms, what is actually happening behind the connections among diet, health and microbiota, have generally been hard to pin down. More research into Bilophila cell biology and ecology is needed, but our study presents a clearly defined mechanism with potential for a big impact on human health.”.
Kivenson said, “The data we reviewed show significantly more Bilophila in the microbiomes of healthy people compared to those with cardiovascular disease, and that Bilophila numbers go up in response to a diet based on meat compared to a plant-based diet. Our findings suggest Bilophila’s role in the microbiome and human health might depend on the specific context and that their potential as a probiotic that mitigates animal products’ role in heart disease should be studied further.”
John M. Burt