Yoghurt fermented by Lactobacillus delbrueckii subsp. bulgaricus H+ -ATPase-defective mutants exhibits enhanced viability of Bifidobacterium breve during storage

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Date
2007Author
Ongol, Martin Patrick
Sawatari, Yuki
Ebina, Yoshiko
Sone, Teruo
Tanaka, Michiko
Tomita, Fusao
Yokota, Atsushi
Asano, Kozo
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Persistent acid production by Lactobacillus delbrueckii subsp. bulgaricus during refrigerated storage is a major cause of reduced viability of
probiotic strains such as Bifidobacterium breve in yoghurt. It was established that H+
-ATPase-defective mutants of lactic acid bacteria have
reduced growth and metabolism in low pH environments. Therefore, the aim of this study was to evaluate inhibition of post-acidification and
maintenance of B. breve viability in yoghurt fermented by L. delbrueckii subsp. bulgaricus mutants with reduced membrane-bound H+
-ATPase
activity during refrigerated storage. Spontaneous neomycin mutants of L. delbrueckii subsp. bulgaricus that had a significantly (P≤0.05) reduced
H+
-ATPase activity were successfully isolated. Yoghurt fermented using L. delbrueckii subsp. bulgaricus SBT0164 No. 55-1 (mutant) starter
culture had markedly reduced post-acidification and maintained viability (≥108 CFU/ml) of both Bifidobacteruim breve JCM 1192T and
Bifidobacteruim breve JCM 7017 during storage at 10 °C for 21 days. These results clearly showed that yoghurt fermented by mutants of
L. delbrueckii subsp. bulgaricus with reduced membrane-bound H+
-ATPase activity has reduced post-acidification that prolongs viability of
B. breve in yoghurt during refrigerated storage.