Fungi growth is impacted by intestinal bacteria.

May 16, 2023 | 09:43:26

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The number of potentially dangerous Candida fungi in the colon can be determined by the bacteria there. Surprisingly, lactic acid bacteria, which are renowned for their capacity to prevent fungal illnesses, are among them.

Understanding the human gut microbiome is now made easier by research from the Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI) and its Danish and Hungarian collaborators.

The community of microorganisms that live in the human gut is incredibly complex and they all interact with one another. If a species is out of balance due to antibiotics or other environmental factors, it might spread and infect people. Many healthy individuals have fungus like Candida in their intestines. Although they are mostly safe, they have the capacity to cause devastating systemic infections.

It is challenging to research these interactions in the intestine. Only a small portion of the several hundred different species of bacteria and fungi can be successfully grown in a lab, and many of them are even unknown. In order to learn more about the intestine, scientists at the Leibniz-HKI are using metagenome research.

In the research, which was just released in Nature Communications, experts looked at feces samples from 75 cancer patients and discovered that when the quantity of fungi from the Candida genus is also large, certain bacterial species invariably show up in increased numbers. Bastian Seelbinder, the study’s principal author, said, “With these data, we developed a computer model that was able to predict the amount of Candida in another group of patients with an accuracy of about 80% based on bacterial species and amounts alone.” Most of the bacteria in this group were oxygen-tolerant varieties.

In Gianni Panagiotou’s microbiota Dynamics section at Leibniz-HKI, Seelbinder carries out research with a strong emphasis on the gut microbiota. The ability to accurately forecast the amount of fungi present based on the species of bacteria present as well as which bacteria connected with high amounts of fungi shocked the researchers fungi. Seelbinder notes that “we found an increased number of bacterial species, including Lactobacillus species, that produce lactic acid.” He was not expecting to find what he did. At first, I had a hard time believing it, so I double-checked multiple times, always coming up empty.

He was surprised because numerous studies have demonstrated how lactic acid bacteria can protect against fungal infections. Panagiotou’s team released one of them in the journal Nature Communications last year. The outcome, according to Panagiotou, “shows once more how complex the human gut microbiome is and how challenging it is to decipher the interactions of different microorganisms.”

The researchers’ theory is that lactic acid bacteria, especially those of the genus Lactobacillus, promote the growth of Candida while also causing the less aggressive fungus. This might be as a result of Candida species’ ability to change their metabolism so they can use the lactate made by lactic acid bacteria. The researchers found that this offers them a competitive edge over other fungi, such as Saccharomyces cerevisiae, in additional studies. The metabolic switch also appears to prevent Candida from developing the potentially harmful fungal hyphae that could infiltrate the intestinal mucosa, keeping it in its typically benign spherical yeast form.

Additionally, it has been suggested that specific Lactobacillus species may have various outcomes, according to Seelbinder. The next stage will be to carry out more thorough genomic analysis of the bacteria to look into this.

For the current investigation, we specifically looked at feces samples from cancer patients who are at risk for developing fungus infections,” says Panagiotou. To establish long-term treatments for at-risk patients based on their microbiomes, other studies should use samples from healthy participants.