Effect of acid adaptation treatment on the acid tolerance and protein expression of Vibrio parahaemolyticus
Date Issued
2011
Date
2011
Author(s)
Tseng, Yu-Ting
Abstract
The objective of this study was conducted to examine the effect of acid adaptation treatment, growth phase and bacterial strain on the survival of Vibrio parahaemolyticus under environmental stresses. The protein expression of V. parahaemolyticus influenced by acid adaptation was also investigated.
In the experiments, cells of V. parahaemolyticus were subjected to various acid adaptation treatments at pH 5.0, 5.5 and 6.0 for 30, 60 and 90 min, respectively. Results showed that the pH value and length of acid adaptation treatment affected the acid tolerance of V. parahaemolyticus. When cells acid-adapted at pH 5.5 and 6.0, the survival of V. parahaemolyticus 690 after exposure at pH 4.5 for 4 h generally increased as the length of acid adaptation treatment extended. Among the various acid adaptation treatments examined, cells of V. parahaemolyticus 690 subjected to acid adaptation at pH 5.5 for 90 min exhibited the highest acid tolerance. The acid-adapted late-exponential phase cells of V. parahaemolyticus 690 had a higher magnitude of increased acid tolerance than the cells acid-adapted in mid-exponential and stationary phases.
Additionally, it was found that the extent of induced acid tolerance on the acid-adapted cells of V. parahaemolyticus varied with the bacterial strain （405, 556, 690, BCRC 13023, BCRC 13025, BCRC 12863 and BCRC 12864） and organic acid （lactic acid, acetic acid, citric acid and propanoic acid） tested. Furthermore, acid adaptation increased the thermal tolerance （47℃） of three V. parahaemolyticus strains （690, BCRC 13023 and BCRC 13025）, while did not affect their cold tolerance （4 and -20℃）, when cells exposed to PBS-3% NaCl. However, the acid-adapted response was not observed in oyster homogenates, the survival of acid-adapted cells exposed to oyster homogenates was similar to that of control cells at high and low temperatures.
Analysis with mini SDS-PAGE and two-dimensional electrophoresis revealed that some proteins were jointly or individually enhanced or even reduced by acid adaptation in cells of V. parahaemolyticus 690, BCRC 13023 and BCRC 13025. In the present study, the induction of these stress proteins might relate to increased tolerance of acid-adapted V. parahaemolyticus to acid and heat stresses. Identification of the stress proteins induced by acid adaptation requires in further studies.
Subjects
Vibrio parahaemolyticus
Acid adaptation
Acid tolerance
Type
thesis
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