Effect of Acid Adaptation on the Survival of Bacillus cereus under Subsequent Environmental Stresses and their Enterotoxin Production
Date Issued
2007
Date
2007
Author(s)
Chen, Jui-Lin
DOI
zh-TW
Abstract
This study was conducted to investigate the effect of acid adaptation on the survival of Bacillus cereus 1-4-1 under subsequent environmental stresses (organic acids, high and low temperatures, high salts, ethanol and hydrogen peroxide). Besides, the enterotoxin production and protein expression of B. cereus 1-4-1 as influenced by acid adaptation were also examined.
It was found that Bacillus cereus 1-4-1 cells subjected to acid adaptation at pH 5.5 for 2 h exhibited the highest percentage of survival after exposure to phosphate buffer solution with pH 4.0 for 4 h. The acid-adapted cells showed a higher tolerance than the non-adapted cells when exposure to phosphate buffer solution (pH 4.0) containing 40mM organic acids (acetic acid, propionic acid, lactic acid, citric acid, tartaric acid). Furthermore, acid adaptation significantly (p<0.05) increased the thermal tolerance (49℃) and freezing (-18℃) resistance of Bacillus cereus 1-4-1. On the other hand, acid adaptation increased the susceptibility of Bacillus cereus 1-4-1 to refrigerative temperature (4℃), high salts (20%) and ethanol (20%). It was also showed no significant difference (p>0.05) susceptibility of the acid-adapted cells and non-adapted cells to hydrogen peroxide (5 mM). The cell-free supernatant and cell lysate of the acid-adapted cells showed less amount of enterotoxin than that of the non-adapted cells. Grown in TSB, the acid-adapted cells exhibited a higher level of growth and enterotoxin production than did the non-adapted cells until after 4 h of cultivation.
Subjects
酸馴化處理
仙人掌桿菌
環境壓力
腸毒素
acid adaptation
Bacillus cereus
environmental stresses
enterotoxin
Type
thesis
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