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.

BackgroundRecent studies have reported the preventive effects of probiotics on obesity. Among commensal bacteria, bifidobacteria is one of the most numerous probiotics in the mammalian gut and are a type of lactic acid bacteria. The aim of this study was to assess the antiobesity and lipid‐lowering effects of Bifidobacterium spp. isolated from healthy Korean on high fat diet‐induced obese rats.MethodsThirty‐six male Sprague‐Dawley rats were divided into three groups as follows: (1) SD group, fed standard diet; (2) HFD group, fed high fat diet; and (3) HFD‐LAB group, fed high fat diet supplemented with LAB supplement (B. pseudocatenulatum SPM 1204, B. longum SPM 1205, and B. longum SPM 1207; 108 ~ 109 CFU). After 7 weeks, the body, organ, and fat weights, food intake, blood serum levels, fecal LAB counts, and harmful enzyme activities were measured.ResultsAdministration of LAB reduced body and fat weights, blood serum levels (TC, HDL‐C, LDL‐C, triglyceride, glucose, leptin, AST, ALT, and lipase levels), and harmful enzyme activities (β‐glucosidase, β‐glucuronidase, and tryptophanase), and significantly increased fecal LAB counts.ConclusionThese data suggest that Bifidobacterium spp. used in this study may have beneficial antiobesity effects.

Pseudomonas aeruginosa and Acinetobacter baumannii are significant opportunistic pathogens in hospitals and are resistant to most antibiotics. Multidrug-resistant P. aeruginosa (MDRPA) and A. baumannii (MDRAB) cause severe human nosocomial infections and are more difficult to treat than methicillin-resistant Staphylococcus aureus (MRSA). Bifidobacteria are among of the most beneficial probiotics and have been widely studied for their antimicrobial activities. The present study explored the antimicrobial activity of Bifidobacterium sp. isolated from healthy Koreans against MDRPA and MDRAB. The antimicrobial activity of the isolates against MDRPA and MDRAB, which are resistant to ciprofloxacin, tobramycin, gentamicin, meropenem, and ceftazidime, was determined by modified broth microdilution methods using absorbance. Among all tested bifidobacteria isolates (nine B. adolescentis, three B. longum, and two B. pseudocatenulatum), the culture supernatant of B. pseudocatenulatum SPM1309 showed a strong growth inhibitory effect against MDRPA and MDRAB. No change in the turbidity of the mixture was observed during incubation, and its inhibitory effect occurred through bacteriostastic action. Moreover, the antibacterial activity was observed in the fraction with molecular weights <10 kDa of bifidobacteria culture supernatant, and the active fraction was heat-stable because it maintained its activity when heated at 70℃ for 10 min. The results suggest that this Bifidobacterium strain could have potential applications for alternative therapy in MDRPA and MDRAB infections.

Probiotics have been reported to benefit human health by modulating immunity, lowering cholesterol, improving lactose tolerance, and preventing some cancer. Once ingested, probiotic microorganisms have to survive harsh conditions such as low pH, protease-rich condition, and bile salts during their passage through the gastro-intestinal (GI) tract colonize and proliferate to exert their probiotic effects. The dual coating technology, by which the bacteria are doubly coated with peptides and polysaccharides in consecutive order, was developed to protect the ingested bacteria from the harsh conditions. The aim of the study was to evaluate the viable stability of a doubly coated blend of four species of Bifidobacterium by comparing its bile/acid resistance and heat viability in vitro with that of the non-coated blend. After challenges with acid, bile salts, heat, and viable cell counts (VVCs) of the dual coated and non-coated blend were determined by cultivation on agar plates or flow cytometric measurement after being stain with the BacLigtht kit TM . The results showed that the dual coated blend was much higher resistant to the acidic or bile salt condition than the non-coated blend and heat viability was also higher, indicating that the dual coating can improve the survival of probiotic bacteria during their transit through the GI tract after consumption.