Hypocholesterolemic effect of sonication-killed Bifidobacterium longum isolated from healthy adult Koreans in high cholesterol fed rats

Abstract

We have previously reported that live Bifidobacterium longum SPM1207, a strain isolated from healthy adult Koreans, significantly reduced serum cholesterol in broth and rat. We here examined the effect of oral administration of sonication-killed B. longum SPM1207 on serum cholesterol in rats in order to investigate whether this killed strain could be utilized as a potent probiotics for human and animals. Dietary treatments consisted of 3 treatment groups of 24 rats each randomly assigned to either normal diet, high cholesterol diet and saline (HCS), or high cholesterol diet and sonication-killed B. longum SPM1207 (HCKB) for 3 weeks. Although HDL-cholesterol levels in the serum were not significantly (p > 0.05) different between HCKB rats and HCS rats, total and LDL-cholesterol levels in the serum were significantly (p < 0.05) less increased in HCKB (total: 177.71 mg/dL, LDL-: 60.50 mg/dL) rats when compared to HCS (total: 237.17 mg/dL, LDL-: 71.50 mg/dL) rats. AI was significantly (p < 0.05) lower in HCKB (4.95 mg/dL) rats when compared to HCS (9.22 mg/dL) rats. Body weight increase and relative liver weight were significantly (p < 0.05) lower in HCKB rats when compared to HCS rats. Over the time, high cholesterol diet caused dry feces accompanied by decreased fecal water content (66.00 to 61.94%) but sonication-killed B. longum SPM1207 administration increased fecal water content (71.58 to 74.25%). The results in the current study provide evidence that the sonication-killed cells of B. logum SPM1207 isolated from healthy adult Koreans have a greater potential to be used as a cholesterol-lowering agent. Furthermore, the current study suggest that this killed specific strain may play role in part in blocking the body weight increase and relieving or eliminating constipation.