title: Yoghurt fermented by Lactobacillus delbrueckii subsp. bulgaricus H+ -ATPase-defective mutants exhibits enhanced viability of Bifidobacterium breve during storage.
abstract: 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 < or = 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 (> or = 10(8) CFU/ml) of both Bifidobacteruim breve JCM 1192(T) and Bifidobacteruim breve JCM 7017 during storage at 10 degrees 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.
authors: Laboratory of Applied Microbiology, Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
authors: Martin Patrick
authors: MP
authors: Ongol
authors: Yuki
authors: Y
authors: Sawatari
authors: Yoshiko
authors: Y
authors: Ebina
authors: Teruo
authors: T
authors: Sone
authors: Michiko
authors: M
authors: Tanaka
authors: Fusao
authors: F
authors: Tomita
authors: Atsushi
authors: A
authors: Yokota
authors: Kozo
authors: K
authors: Asano
mesh_terms: D001644:Bifidobacterium / Q000254:growth & development*; D015169:Colony Count, Microbial; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D048668:Lactobacillus delbrueckii / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000172:deficiency* / Q000235:genetics; D013696:Temperature; D013997:Time Factors; D015014:Yogurt / Q000382:microbiology*
chemical_list: D006180:Proton-Translocating ATPases