a b s t r a c t
The aim of the present study was to determine the survival of Salmonella Typhimurium adapted with
sodium lactate (NaL), potassium lactate/sodium acetate mixture (KL/NaA) or sodium acetate (NaA) in
simulated gastric fluid (SGF) and during heat treatment. NaL-, KL/NaA- and NaA-adapted cells were
prepared by incubating in tryptic soy broth (TSB) containing these salts at 5, 5 and 3% (w/v) concentration
levels, respectively, for 24 h at 37 C. The Baranyi model was used to compare the growth
kinetic parameters of adapted cells. The acid and heat resistance of adapted cells were determined by
incubating in SGF (pH 2.04) at 37 C and in TSB at 55.8, 57.8 and 59.8 C, respectively. Adapted cells had
significantly (P < 0.05) longer lag phase duration (LPD) and slower maximum growth rate (MGR) than
non-adapted cells. The acid resistance of KL/NaA-adapted cells was not significantly (P > 0.05) different
from that of non-adapted cells. NaL-adapted cells were more susceptible to the low pH environment,
whereas NaA-adapted cells showed enhanced acid resistance compared to non-adapted and other
adapted cells. Unlike acid resistance, both NaL- and NaA-adapted cells showed enhanced heat resistance
with increased D-values, regardless of treatment temperatures. Thus, this study indicates that adaptation
of S. Typhimurium to 5% NaL or 3% NaA could enhance their ability to survive thermal processes or in the
human stomach, possibly increasing the risk of Salmonella outbreaks
a b s t r a c tThe aim of the present study was to determine the survival of Salmonella Typhimurium adapted withsodium lactate (NaL), potassium lactate/sodium acetate mixture (KL/NaA) or sodium acetate (NaA) insimulated gastric fluid (SGF) and during heat treatment. NaL-, KL/NaA- and NaA-adapted cells wereprepared by incubating in tryptic soy broth (TSB) containing these salts at 5, 5 and 3% (w/v) concentrationlevels, respectively, for 24 h at 37 C. The Baranyi model was used to compare the growthkinetic parameters of adapted cells. The acid and heat resistance of adapted cells were determined byincubating in SGF (pH 2.04) at 37 C and in TSB at 55.8, 57.8 and 59.8 C, respectively. Adapted cells hadsignificantly (P < 0.05) longer lag phase duration (LPD) and slower maximum growth rate (MGR) thannon-adapted cells. The acid resistance of KL/NaA-adapted cells was not significantly (P > 0.05) differentfrom that of non-adapted cells. NaL-adapted cells were more susceptible to the low pH environment,whereas NaA-adapted cells showed enhanced acid resistance compared to non-adapted and otheradapted cells. Unlike acid resistance, both NaL- and NaA-adapted cells showed enhanced heat resistancewith increased D-values, regardless of treatment temperatures. Thus, this study indicates that adaptationof S. Typhimurium to 5% NaL or 3% NaA could enhance their ability to survive thermal processes or in theกระเพาะมนุษย์ อาจเพิ่มความเสี่ยงของการแพร่ระบาดระดับ
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