BackgroundLactic acid bacteria (LAB) are beneficial probiotic organisms that contribute to improved nutrition, microbial balance, and immuno-enhancement of the intestinal tract, as well as lower cholesterol. Although present in many foods, most trials have been in spreads or dairy products. Here we tested whether Bifidobacteria isolates could lower cholesterol, inhibit harmful enzyme activities, and control fecal water content.MethodsIn vitro culture experiments were performed to evaluate the ability of Bifidobacterium spp. isolated from healthy Koreans (20~30 years old) to reduce cholesterol-levels in MRS broth containing polyoxyethanylcholesterol sebacate. Animal experiments were performed to investigate the effects on lowering cholesterol, inhibiting harmful enzyme activities, and controlling fecal water content. For animal studies, 0.2 ml of the selected strain cultures (108~109 CFU/ml) were orally administered to SD rats (fed a high-cholesterol diet) every day for 2 weeks.ResultsB. longum SPM1207 reduced serum total cholesterol and LDL levels significantly (p < 0.05), and slightly increased serum HDL. B. longum SPM1207 also increased fecal LAB levels and fecal water content, and reduced body weight and harmful intestinal enzyme activities.ConclusionDaily consumption of B. longum SPM1207 can help in managing mild to moderate hypercholesterolemia, with potential to improve human health by helping to prevent colon cancer and constipation.

Bifidobacteria are considered one of the most beneficial probiotics and have been widely studied for their effects in preventing and treating specific pathological conditions. The present study explored the antiviral activity of Bifidobacterium adolescentis SPM0212 isolated from healthy Koreans against hepatitis B virus (HBV) and its mechanism of action. To determine the effect of B. adolescentis SPM0212 against HBV, the level of HBV surface antigen (HBsAg) in the culture medium and the levels of viral transcripts in HepG2.2.15 cells were measured by enzyme-linked immunosorbent assay and reverse transcription-quantitative PCR (RT-qPCR), respectively. To clarify the mechanism, we performed RT-qPCR using specific primers for genes encoding Interferon (IFN)-signaling components and IFN-inducible antiviral effectors. The cell extract of B. adolescentis SPM0212 dose-dependently decreased the extracellular HBsAg level by up to 50 %. Its gene expression in HepG2.2.15 cells was also inhibited by 40 %. This extract significantly increased the expression level of myxovirus resistance A, which is an IFN-inducible antiviral effector. Furthermore, the antiviral activity was observed in the fraction of compound(s) with molecular weights under 30 kDa. Thus, the cell extract of B. adolescentis SPM0212 inhibits HBV and its antiviral mechanism is associated with the Mx GTPase pathway.

Rotavirus is worldwide cause of severe gastroenteritis including severe diarrhea and fatal dehydration in infants and young children. There is an available vaccination program for preventing rotavirus infection, but it has limits and restrictions. Probiotics therapy could be an alternative method of antiviral prevention and modulation against rotavirus infection. In this study, we screened the antiviral activity of probiotic bacteria such as 3 Lactobacillus spp. and 14 Bifidobacterium spp. isolated from young Korean. Three of the bacteria, Lactobacillus ruminis SPM0211, Bifidobacterium longum SPM1205, and SPM1206, inhibited human strain Wa rotavirus infection in Caco-2 cells. Furthermore, these bacterial strains inhibited rotavirus replication in a rotavirus-infected neonatal mouse model. To clarify the mechanism of inhibition, we investigated gene expression of Interferon (IFN)-signaling components and IFN-inducible antiviral effectors. All 3 probiotics increased IFN-α and IFN-β levels compared with the control. Gene expression of IFNsignaling components and IFN-inducible antiviral effectors also increased. Overall, these results indicate that L. ruminis SPM0211, B. longum SPM1205 and 1206 efficiently inhibit rotavirus replication in vitro and in vivo. Especially, the antiviral effect of Lactobacillus ruminis SPM0211 is worthy of notice. This is the first report of L. ruminis with antiviral activity. Anti-rotaviral effects of the 3 probiotics are likely due to their modulation of the immune response through promoting type I IFNs, which are key regulators in IFN signaling pathway.

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.

Bifidobacterium strains can provide several health benefits, such as antimicrobial and immunomodulatory effects. Some strains inhibit growth or cell adhesion of pathogenic bacteria, including multidrug-resistant bacteria, and their antibacterial activity can be intensified when combined with certain antibiotics. In addition, some strains of bifidobacteria reduce viral infectivity, leading to less epithelial damage of intestinal tissue, lowering the virus shedding titer, and controlling the release of antiviral substances. Furthermore, bifidobacteria can modulate the immune system by increasing immunoglobulins, and inducing or reducing pro- or antiinflammatory cytokines, respectively. In particular, these anti-inflammatory effects are helpful in the treatment of patients who are already suffering from infection or inflammatory diseases. This review summarizes the antimicrobial effects and mechanisms, and immunomodulatory effects of Bifidobacterium strains, suggesting the potential of bifidobacteria as an alternative or complementary treatment option.