Fundamental study on yeasts from dairy origin for the novel probiotic application

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 16500502
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Eating habits, studies on eating habits
• Research Institution: HOKKAIDO UNIVERSITY
• Principal Investigator: KUMURA Haruto Hokkaido Univ., Research Faculty of Agriculture, Associate Professor, 大学院農学研究院, 助教授 (00241365)
• Project Period (FY): 2004 – 2006
• Keywords: probiotics / yeast / fermented dairy products

Research Abstract

In recent years, attention is being paid to the effect of fermented food products on the human health, especially probiotic microorganisms including lactic acid bacteria and Bifidobacterium spp. In this study, immunomodulatory effects and ability of promoting growth and improving viability of Bifidobacterium spp. of some yeast isolated from dairy origin were investigated.
Despite statistical insignificance, oral administration of some yeasts resulted higher level of immunoglobulin A in the large intestine content of mice. Furthermore, spleen cells prepared from ovalbumin (OVA) immunized mice were incubated in the presence or absence of either OVA, lactic acid bacteria or the 12 yeast strains of 6 species. The results showed that the addition of OVA in the culture of spleen cells stimulated production of immunoglobulin E (IgE); conversely the addition of lactic acid bacteria or yeast cells debris to the culture suppressed IgE production. Although the suppression of IgE production and no induction of IFN-gamma were observed by all yeast strains tested; the level of IL-12 in the culture was found to be strain dependent. In addition, oral administration of a yeast and/or lactic acid bacteria to OVA immunized mice was conducted to monitor the serum IgE level. Reduction of serum IgE level in the experimental group was found to be undetectable as compared with control group. Ability of yeast cell to promote growth and improve viability during refrigeration storage of Bifidobacterium spp. was observed by the addition of yeast extracts to skim culture. Factor(s) associated with growth promotion of Bifidobacterium spp. was found to be thermostable because the effect was being existed even after boiling treatment with skim milk for 30 min.
Yeast isolated from traditional food is considered as safe and an attractive source to design novel functional foods. Further investigation should be conducted f or beneficial application of yeast.