Despite the fact that bacterial metabolism plays a major role in the gut microbiome, little has been known about the metabolic capabilities of most gut bacteria until now. In a recent study, EMBL scientists sought to fill in the information gap by examining 96 phylogenetically diverse gut bacterial strains and 19 different growth media. Details on the study were published today in Nature Microbiology .
The research team selected 96 strains from 72 bacterial species, representing the most frequently occurring and most abundant species in the human gut plus important species linked to infectious or other types of gut diseases, like colorectal cancer and inflammatory bowel disease. While characterizing their nutritional preferences and ability to produce various molecules, the researchers discovered unknown metabolic features of some bacteria.
"We were surprised to find new bacteria with the capability to utilize mucin, the protein that makes up mucus," says Kiran Patil. "These bacteria can contribute to inflammation and infection by weakening the protective mucus barrier lining the gut. Another surprise came from bacteria that proved to be inhibited by amino acids and short-chain fatty acids, common ingredients in most growth media. It turns out that rich media with many nutrients can be toxic for these species, whereas we used to think: the more food, the better."
Furthermore, even closely related bacteria sometimes had completely different nutritional preferences, which, according to the team shows that microbiologists can't base their assumptions about metabolic capabilities on bacteria's genetic relationships alone.