2023-09-25 16:15:05
The microorganisms that live in the intestine (microbiota) act as a bioreactor that metabolizes the nutrients that our body does not use (mainly complex, non-digestible carbohydrates, such as fiber), which, in turn, nourish the intestinal bacteria. In return, many of these produce beneficial substances for the human body. In addition, the bacteria that live in the intestine interact with each other, exchanging nutrients to increase their survival. Deciphering the interactions between bacteria and our body is essential to foster beneficial microbial cooperative relationships and develop applications that improve the intestinal ecosystem and, thus, the health of the individual.
Some diseases, antibiotic use, and unhealthy diets can reduce the abundance and survival of health-promoting gut bacteria. One solution would be to replenish reduced or extinct bacterial species through administration. Something seemingly simple. However, most of them do not resist the presence of oxygen, so their cultivation is very complex and requires in vitro conditions that are difficult to achieve. Its survival and benefits also depend on the interaction with other bacteria, which are difficult to identify and reproduce.
The team led by Muhammad Tanweer Khan, from the University of Gothenburg in Sweden, has identified two bacterial species (Faecalibacterium prausnitzii and Desulfovibrio piger) that interact with each other through a nutrient exchange mechanism that makes them indispensable partners. Specifically, F. prausnitzii consumes carbohydrates such as glucose and produces lactate, which is used by D. piger to produce acetate, which, in turn, is used by F. prausnitzii to produce butyrate.
This fatty acid is the main source of energy for the epithelial cells of the intestine. It also helps reduce inflammation and maintain the integrity of the intestinal barrier. Beyond its role in the intestine, butyrate can reduce liver inflammation and help regulate blood glucose levels and control the balance between energy intake and expenditure, the alteration of which would lead to the development of overweight and obesity.
Some diseases, the use of antibiotics and unhealthy diets can reduce the abundance and survival of intestinal bacteria that promote our health. (Illustration: Amazings/NCYT)
The Swedish researchers managed to increase the resistance of F. prausnitzii to a more oxygen-rich environment, which facilitated the production of this bacteria in vitro. They grew the bacteria in a bioreactor that simulates the intestinal environment and progressively increased the oxygen levels, isolating the colonies that survived this treatment. Through sequencing its genome, they identified several mutations in F. prausnitzii that are more tolerant to oxygen. This helped produce sufficient quantities of this bacteria in vitro and conduct trials in rodents and humans with the two bacteria.
Scientist Yolanda Sanz, researcher at the Higher Council for Scientific Research (CSIC) at the Institute of Agrochemistry and Food Technology (IATA), Spain, has recently published in the academic journal Nature an analysis that examines the role that intestinal bacteria could have. in the development of new generation probiotics to protect our health. The analysis examines the results of the aforementioned research carried out at the University of Gothenburg.
An important aspect considered in the analysis of the study is safety. “Classical probiotics, mostly belonging to species of the Lactobacillus and Bifidobacterium genera, have a history of safe use in food. However, the safety of using intestinal bacteria as probiotics must be rigorously evaluated, despite the fact that in many cases they are commensal bacteria that live with us,” explains Sanz, researcher in the IATA Microbiome, Nutrition and Health group.
The Swedish research group concluded that oral administration of the combination of the two bacteria did not cause adverse effects in mice or in the 50 healthy volunteers who participated in a clinical trial. The study also evaluated the ability of the administered bacteria to colonize, at least transiently, the intestinal tract. The authors detected the presence of DNA from ingested bacteria in some subjects, but not in all volunteers. “It is reasonable to expect that the administered bacteria integrate more easily into an intestinal ecosystem altered by a disease than into an undamaged ecosystem such as that of healthy individuals, which must resist colonization by foreign bacteria,” says Sanz.
“These results support the idea that reintroducing bacteria to repair the intestinal ecosystem is a promising strategy to promote health and control diseases, although there are still great challenges to overcome,” says the CSIC scientist. In her opinion, the greatest challenge is the identification and recreation of microbial interactions that are expected to be beneficial for the human organism, as well as the cultivation and preservation of these bacteria outside the intestine. Solving these challenges will be key in the production of the next generation of probiotics. However, “we are getting closer to being able to take advantage of our microorganisms to improve human health,” concludes the researcher. (Source: CSIC)
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