It is reported that "Probiotics" such as genus Lactobacillus and Bifidobacterium have various physiological effects on a host. For those various actions to take place, the adhesion of probiotic lactic acid bacteria (LAB) to the human intestinal tract is very important. It is thought that probiotic LAB colonizes the intestinal tract by adhering to mucin, extracellular matrix, and lectin like protein that exist in the human intestinal tract, then propagates. S-layer, lectin-like, and other proteins, and the lipoteichoic acids exist on the bacterial cell surface and work as "adhesin". Especially, the adhesion mediated by lectin-like proteins is very specific and interesting. The adhesion test is generally performed by measuring optical absorbance or observation with a microscope using the Caco-2 cell line as a human intestinal tract model. We developed a new evaluation system with the "BIACORE" biosensor which utilizes the surface plasmon resonance (SPR) and discovered some LAB strains recognizing the human blood type antigen. We think the possibility of discovering a new adhesin with the new system is very high, and it will be very useful for probiotic research in the future.

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Lactococcus lactis subsp. lactis C 101910, isolated from lake water collected in Lake Motosu, Japan, was found to produce a bacteriocin-like inhibitory substance (BLIS) active against some Gram-positive bacteria. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the partially purified BLIS contained one antibacterial band approximately 2.5 kDa in size. When it was amplified with nisin-specific polymerase chain reaction (PCR) primers, a 320-bp PCR product was obtained. The PCR product was further sequenced and found to completely coincide with the sequences of nisin Z. This strain showed good performance in terms of growth and BLIS production when incubated in a simple broth at a low temperature. This is the first report to describe the characteristics of a lake-water-isolated strain of Lactococcus lactis subsp. lactis and to demonstrate that it produces a bacteriocin.

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Secretory IgA is an important immunoglobulin which provides an immunological barrier to foreign matter, particularly pathogenic microorganisms and allergenic food proteins, by preventing absorption of such material by mucosal epithelium and penetration into the body.
IgA is the predominant immunoglobulin isotype that acts to protect the mucosal surface from microbacteria attacks. Enhancement of IgA is important for host defense. In this study, we demonstrated the effect of lactic acid bacteria on the mucosal immune response, in vitro and ex vivo.
In the in vitro study, we tested 150 lactic acid bacteria for their IgA production capabilities using a murine Peyer’s patche cell culture system. By screening for abilities of IgA production, we found two strains of lactic acid bacteria derived from tea, Lactobacillus plantarum ONRICb 0239 (b 0239) and ONRICb 0240 (b 0240), which had particularly excellent IgA production capabilities in vitro.
Next, we attempted an ex vivo study of b 0240, which was the most effective strain for IgA production. Balb/c mice were administerd b 0240 or saline (control group) for 7, 14 and 21 days. After 21 days, the total IgA concentrations of the culture supernatants and the serum total IgG concentrations were determined.
After 21 days of administration, both viable and non-viable b 0240 significantly enhanced IgA production, and non-viable b 0240 tended to increase serum IgG production (P=0.0582).
These results suggest that b 0240, derived from tea, promote IgA production via activating mucosal immunity, like vaccination with poliomyelitis anterior acuta. Also, b 0240 increases IgG in serum. Both of these effects might enable a host organism to protect itself from internal and external microorganisms.
Both viable and non-viable cells exhibiting activity, like b 0240, are expected to be useful in new immunobiotics, such as oral vaccines.

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