Milk Science
Online ISSN : 2188-0700
Print ISSN : 1343-0289
ISSN-L : 1343-0289
Volume 63, Issue 3
Displaying 1-3 of 3 articles from this issue
Original Papers
  • Xiaoyan Guo, Hiroshi Uenishi, Yasushi Kawai, Narimi Yasuta, Genki Kasu ...
    2014 Volume 63 Issue 3 Pages 129-135
    Published: 2014
    Released on J-STAGE: December 21, 2014
    JOURNAL FREE ACCESS
     Gassericin T, a class IIb bacteriocin with two complementary peptides, is produced by Lactobacillus gasseri commonly found in human intestines. L. gasseri strains containing bacteriocinogenic LA158 isolated from a human infant in our laboratory grew well in modified milk-based media, but the gassericin T production by LA158 was inhibited by high concentrations of divalent metal cations in the milk-based media. In this study, it was confirmed that gassericin T production by L. gasseri SBT2055, which has an antiobesity effect, was specifically inhibited in MRS broth by adding divalent metal cations (Mg2+, Ca2+, Mn2+, Fe2+, and Zn2+) depending on the concentration of cations, although the effective concentrations were different from those in LA158 tested (Mg2+ and Ca2+). The addition of 200 mM divalent metal cations resulted in the almost complete disappearance of gassericin T despite a good cell growth. Furthermore, gassericin T production was restored by adding trisodium citrate dihydrate (TSC), which is a food-grade chelator of divalent cations. These findings may contribute to the effective use of bacteriocinogenic L. gasseri strains as probiotics for yogurt manufacture without the inhibition of growth of starter strain(s).
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  • Masayuki Watanabe, Mitsuru Homma, Hiroshi Uenishi, Yosuke Fujimoto, Y ...
    2014 Volume 63 Issue 3 Pages 137-144
    Published: 2014
    Released on J-STAGE: December 21, 2014
    JOURNAL FREE ACCESS
     We investigated the effect of sugar starvation treatment on the stress resistance of lactobacilli incubated in de Man, Rogosa, and Sharpe (MRS) medium without added glucose. Lactobacillus gasseri SBT2055 incubated in MRS medium in the absence of sugar showed higher survival rates at pH 3.6 or with 25 mg/L of hydrogen peroxide stored at 10℃. The expression levels of all the genes examined (atpD, cfa, clpC, dnaK, ftsH, groEL, hsp20, ldh, mscL, pox, opuA, ptsH, rpoD, trxA, uvrA) decreased after sugar starvation. On decreasing the pH of the medium, radical formation and a decrease in viable cell count were observed; however, the viability of sugar-starved cells improved and radical formation decreased at pH 3.6. Furthermore, from the six Lactobacillus species, only Lactobacillus gasseri and Lactobacillus johnsonii, incubated in MRS medium without added glucose at 37℃ for 18 h, showed an increase in viable cell count after 10 d of storage in a high sugar content solution (26% Brix) at 10℃. These results suggested that the sugar starvation pretreatment may provide a tool for improving the survival rate during processing and storage.
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  • Hiroshi Kawakami, Hyuntae Park, Sungjin Park, Yukitoshi Aoyagi
    2014 Volume 63 Issue 3 Pages 145-153
    Published: 2014
    Released on J-STAGE: December 21, 2014
    JOURNAL FREE ACCESS
     We investigated the relationship between milk intake, habitual physical activity, and body composition in 179 free-living healthy Japanese individuals (88 men and 91 women) aged 65-84 years. An electronic pedometer/accelerometer was attached to the subjects to measure the number of steps taken and the intensity of physical activity, which was expressed in metabolic equivalents (METs, multiples of resting metabolic rate); nutritional status and milk intake was assessed using a food frequency questionnaire. Body composition was assessed using a bioelectrical impedance analyzer, and calcaneal bone stiffness was evaluated on the basis of the osteo sono-assessment index. All subjects were divided into a low milk-intake group (<200 mL/day) and high milk-intake group (≧200 mL/day). We detected statistically significant differences (p<0.05) in year-averaged step count, year-averaged duration of physical activity >3METs, walking velocity, trunk muscle mass, appendicular lean tissue index, calcaneal osteo sono-assessment index, and serum albumin concentration between the low and high milk-intake groups. In particular, a correlation was found between milk intake and appendicular lean tissue index in the male subjects, and between milk intake and bone intensity in the female subjects. Adjusted odds ratios for the estimated risk of developing sarcopenia by multivariate logistic regression analysis indicated a synergistic interaction between milk intake and physical activity. The risk was significantly higher in the low milk-intake/low physical activity group than the other three groups (high milk-intake/high physical activity, high milk-intake/low physical activity, and low milk-intake/high physical activity). The results suggested that milk intake in the elderly may be beneficial for maintaining habitual physical activity and improving body composition.
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