The gut bacterium Streptococcus salivarius may be a suitable probiotic candidate in research on obesity, blood sugar, and excessive sugar intake, according to new findings from a collaborative research team comprised of people from Kyoto University, Noster, Inc., and others.

The bacterium, which is naturally-occurring in the human body, converts dietary sucrose into beneficial exopolysaccharides (EPS), complex carbs which the body can’t break down. Those carbs, in turn, are further metabolized by other bacterial species into short-chain fatty acids, which come with their own respective metabolic health benefits.

S. salivarius is unique in its ability to produce large quantities of EPS, the authors noted.

The study included several experiments. First, the researchers conducted microbial screening from 470 human donors, and identified S. salivarius as a dominant EPS producer in individuals with lower body mass index. Obese donors had significantly reduced levels of this bacterium.

The researchers then conducted an animal study. In high-fat diet-induced obese mice, supplementation with S. salivarius-produced EPS significantly reduced weight gain, fat accumulation, and blood glucose levels compared to that of the control mice. This demonstrated that S. salivarius may have protective effects against obesity, the authors reported.

The EPS produced by the probiotic were fermented by gut microbes like Bacteroides into short-chain fatty acids, including acetate and propionate, which interact with host receptors to regulate metabolism and energy balance.

The researchers conducted a genomic analysis using advanced sequencing techniques, and were able to pinpoint the specific genes in S. salivarius responsible for EPS production, such as glycosyltransferases and levansucrases, which are enzymes crucial for building polysaccharides.

S. salivarius is a potential biomarker for metabolic health and obesity resistance, the authors concluded, due to its unique ability to convert sucrose into health-promoting compounds. “By leveraging the unique properties of S. salivarius and its ability to produce beneficial metabolites, we can open new doors for addressing obesity and related metabolic disorders,” said Ikuo Kimura, researcher at Kyoto University.