熱震處理影響Enterobacter sakazakii在後續致死環境下之存活

Heat Shock Treatment Affects the Survival of Enterobacter sakazakii Subjected to Subsequent Lethal Conditions

張家祥(Chia-Hsiang Chang)

指導教授 ： 周正俊

國立臺灣大學/生物資源暨農學院/食品科技研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.00368

摘要

Enterobacter sakazakii (Cronobacter spp. gen. nov.) 是一種新興食源性病原菌，能夠存在於嬰兒配方奶粉中並可能引起嬰兒致命性的感染，因而近年來在食品衛生安全上愈受重視。本研究中測定了E. sakazakii BCRC 13988於不同熱震條件下 (42∼48℃，5∼15分鐘)，對於熱耐受性之影響，並探討熱震處理之E. sakazakii於後續壓力環境 (低水活性、低溫及乙醇) 中存活之情形。
結果發現熱震處理能提升E. sakazakii BCRC 13988對熱之抵抗力；在所測試之熱震條件中，以47℃處理15分鐘之熱震處理最能提高菌體於後續51℃下之存活。當熱震溫度提高、處理時間增加時，胞外溶液中A260及A280下之吸光值皆逐漸提升。此外，以47℃處理15分鐘，細胞之顯微圖像顯示E. sakazakii菌體經此熱震處理後，細胞有形變及破損之現象；此熱震處理也顯著地提高了E. sakazakii BCRC 13988菌體在後續高滲透壓 (75% sorbitol)、空氣乾燥、冷藏 (3℃)、凍藏 (-20℃) 及15%酒精環境下之忍受性。

關鍵字

Enterobacter sakazakii ； Cronobacter ； 熱震 ； 熱耐受性

並列摘要

Enterobacter sakazakii is an emerging opportunistic pathogen which has been associated with life-threatening cases in infants, with infant formulas been implicated as the mode of transmission. In the present study, E. sakazakii BCRC 13988, the type strain, was subjected to various heat shock treatments (42-48℃, 5-15 min). Their subsequent survival at 51 ℃ and leakage of intracellular materials were investigated. Additionally, survivals of heat-shocked E. sakazakii BCRC 13988 during subsequent exposure to various stress conditions, including high osmotic pressure (75% sorbitol), air drying, low temperature (3 and -20℃) and ethanol (15%), were also investigated.
Results revealed that heat shock treatments increased the thermal tolerance of E. sakazakii BCRC 13988. Heating at 47℃ for 15 min, among the various heat shock treatments examined, was found to enhance the survival of test organism at 51℃ most profoundly. Electron micrograph showed that heat shock treatment caused the damage and disruption of the E. sakazakii BCRC 13988 cells. The extracellular 260 and 280 nm-absorbing materials increased as the temperature and the period of heat treatment were increased. Besides, the heat-shocked cells of test organism exhibited enhanced survival when they were exposure to high osmotic pressure, air drying, ethanol, refrigerated or frozen storage.

並列關鍵字

Enterobacter sakazakii ； Cronobacter ； heat shock ； heat tolerance

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