Functional evaluation of Clostridium isatidis related bacteria in high-fat diet-induced obese mice

Background and Objectives: Thermophile-fermented compost is an agricultural material produced by the fermentation of unutilized marine resources under high temperature and aerobic conditions. Previous studies have shown that the administration of the compost has beneficial effects such as lowering the disease incidence and promoting the growth of piglets. It has also been reported that Bacillus hisashii N-11T strain identified from the cecal feces of gnotobiotic mice fed with thermophile-fermented compost reduces the accumulation of visceral fat in mice and pigs. In addition, a bacterium that is closely relative to Clostridium. isatidis have also been isolated from the cecal feces, but their biological function has not been evaluated. In this study, we investigated the effect of C. isatidis. on high-fat diet-induced obese mice. Methods: Five-week-old male C57BL/6J mice were fed with a normal-fat diet (NFD) or a 60% kcal high-fat diet (HFD). Mice of each diet group were received one of the following doses of C. isatidis. in drinking water; 0 (control), 5.0×102 (low), or 1.0×108 (high) cfu/mouse/day. After performing oral glucose tolerance test (OGTT), mice were sacrificed at the 17th week. Results: Body weight gain was significantly decreased under NFD and tended to be decreased under HFD by C. isatidis. Plasma glucose level during OGTT performed to evaluate glucose metabolism tended to be reduced by C. isatidis. under both diets. In addition, plasma insulin level during OGTT was significantly decreased by a high amount of C. isatidis. under HFD. Furthermore, the exposure significantly decreased triglyceride level in the liver under HFD. Conclusion: These results suggested that C. isatidis. could improve abnormal glucose and lipid metabolism induced by a high-fat diet.