A research group including Kyoto University and Tokyo University of Agriculture and Technology has discovered intestinal bacteria that prevent sucrose-induced obesity by converting sugar (sucrose) into a dietary fiber-like substance called indigestible exopolysaccharide (EPS).
A diet high in sucrose is a significant risk factor for metabolic diseases such as obesity and diabetes. On the other hand, gut bacteria can use these sugars as an energy source and produce indigestible polysaccharides, EPS, through sugar metabolism. EPS is converted into short-chain fatty acids by the assimilating bacteria (bacteria that use EPS to grow or obtain energy), contributing to the metabolic benefits of the host.
The research group then searched for high EPS-producing bacteria among human intestinal bacteria and identified Streptococcus salivarius (S.salivarius). When the EPS (SsEPS) produced by S.salivarius using sucrose as a substrate was examined, it was found to be a dietary fiber-like substance that is a non-digestible polysaccharide. They also confirmed that Bacteroides ovatus (B.ovatus) and Bacteroides thetaiotaomicron (B.thetaiotaomicron), which are predominant species in the human intestine, grew and produced short-chain fatty acids when SsEPS was added.
Next, the effects of SsEPS were examined using obese mouse models, and mice that consumed SsEPS for a long period of time showed suppression of weight gain, and showed increases in the concentrations of B. ovatus and B. thetaiotaomicron and short-chain fatty acids, as well as improvements in metabolic parameters such as blood glucose levels. Furthermore, when model mice colonized with SsEPS-producing bacteria and assimilatory bacteria (B. ovatus and B. thetaiotaomicron) were given sucrose for a long period of time, EPS production in the intestines was observed, and suppression of weight gain, increases in the concentration of short-chain fatty acids, and improvements in metabolic parameters such as blood glucose levels were observed.
These results reveal that EPS-producing bacteria not only suppress sugar absorption in the host by converting sucrose into EPS, but also that EPS-utilizing bacteria use the synthesized EPS to produce short-chain fatty acids, improving the intestinal environment and preventing sucrose-induced obesity.
It is hoped that this discovery will lead to the development of new methods for preventing and treating metabolic diseases such as obesity and diabetes.
Paper information:[Nature Communications] Sucrose-preferring gut microbes prevent host obesity by producing exopolysaccharides
