...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Applied and Environmental Microbiology >Survival of Escherichia coli O157:H7 in broth and processed salami as influenced by pH, water activity, and temperature and suitability of media for its recovery.
【24h】

Survival of Escherichia coli O157:H7 in broth and processed salami as influenced by pH, water activity, and temperature and suitability of media for its recovery.

机译：大肠杆菌O157：H7在肉汤和加工的香肠中的存活率受pH，水分活度，温度和培养基对其回收率的适应性的影响。

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The survival of unheated and heat-stressed (52 degrees C, 30 min) cells of Escherichia coli O157:H7 inoculated into tryptic soy broth (TSB) adjusted to various pHs (6.0, 5.4, and 4.8) with lactic acid and various water activities (a(w)s) (0.99, 0.95, and 0.90) with NaCl and incubated at 5, 20, 30, and 37 degrees C was studied. The performance of tryptic soy agar (TSA), modified sorbitol MacConkey agar (MSMA), and modified eosin methylene blue agar in supporting colony development of incubated cells was determined. Unheated cells of E. coli O157:H7 grew to population densities of 10(8) to 10(9) CFU ml-1 in TSB (pHs 6.0 and 5.4) at an a(w) of 0.99. Regardless of the pH and a(w) of TSB, survival of E. coli O157:H7 was better at 5 degrees C than at 20 or 30 degrees C. At 30 degrees C, inactivation or inhibition of growth was enhanced by reduction of the a(w) and pH. A decrease in the a(w) (0.99 to 0.90) of TSB in which the cells were heated at 52 degrees C for 30 min resulted in a 1.5-log10 reduction in the number of E. coli O157:H7 cells recovered on TSA; pH did not significantly affect the viability of cells. Recovery was significantly reduced on MSMA when cells were heated in TSB with reduced pH or a(w) for an increased length of time. With the exception of TSB (a(w), 0.90) incubated at 37 degrees C, heat-stressed cells survived for 24 h in recovery broth. TSB (a(w), 0.99) at pH 6.0 or 5.4 supported growth of E. coli O157:H7 cells at 20 or 37 degrees C, but higher numbers of heated cells survived at 5 or 20 degrees C than at 37 degrees C. The ability of unheated and heat-stressed E. coli O157:H7 cells to survive or grow as affected by the a(w) of processed salami was investigated. Decreases of about 1 to 2 log10 CFU g-1 occurred soon after inoculation of salami (pHs 4.86 and 4.63 at a(w)s of 0.95 and 0.90, respectively). Regardless of the physiological condition of the cells before inoculation into processed salami at an a(w) of either 0.95 or 0.90, decreases in populations occurred during storage at 5 or 20 degrees C for 32 days. If present at modified eosin methylene blue agar > MSMA.
机译：接种到胰蛋白酶大豆肉汤（TSB）中的大肠杆菌O157：H7的未加热和热应激的细胞（52摄氏度，30分钟）的存活率，已通过乳酸和多种水分活度调节至各种pH（6.0、5.4和4.8） （a（w）s）（0.99、0.95和0.90）与氯化钠并在5、20、30和37摄氏度下孵育的情况进行了研究。确定了胰蛋白酶大豆琼脂（TSA），修饰的山梨糖醇MacConkey琼脂（MSMA）和修饰的曙红亚甲基蓝琼脂在支持孵育细胞集落发育中的性能。大肠杆菌O157：H7的未加热细胞在s的a（w）为0.99的条件下在TSB（pHs 6.0和5.4）中增长到10（8）至10（9）CFU ml-1的种群密度。不管TSB的pH和a（w）是多少，大肠杆菌O157：H7在5摄氏度下的存活都比在20或30摄氏度下更好。在30摄氏度下，通过降低细菌的存活率可以增强灭活或抑制生长的能力。 a（w）和pH。 TSB的a（w）（0.99至0.90）降低，其中将细胞在52摄氏度加热30分钟，导致在TSA上回收的大肠杆菌O157：H7细胞数量减少1.5 log10。 pH值并未显着影响细胞的活力。当在TSB中以降低的pH或a（w）加热细胞的时间延长时，在MSMA上的回收率显着降低。除了将TSB（a（w），0.90）在37摄氏度下温育之外，热应激细胞在回收肉汤中存活了24小时。 pH值为6.0或5.4的TSB（a（w），0.99）支持大肠杆菌O157：H7细胞在20或37摄氏度下的生长，但是在5或20摄氏度下存活的细胞数量要多于37摄氏度。研究了未加热和热应激的大肠杆菌O157：H7细胞在受加工香肠的a（w）影响下存活或生长的能力。接种萨拉米香肠后很快发生了约1-2 log10 CFU g-1的下降（pH值为4.86和4.63，a（w）分别为0.95和0.90）。无论以0.95或0.90的a（w）接种到加工的萨拉米香肠中之前，细胞的生理状况如何，在5或20摄氏度下存储32天的过程中种群数量都会减少。如果在修饰的曙红亚甲基蓝琼脂上存在> MSMA。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号