- 期刊
煮沸時程與頻率以及47℃水浴放置時程不影響Violet Red Bile Glucose Agar檢測腸桿菌科的能力
Duration and Frequency of Boiling and Length of 47°C-Keeping Time Do not Affect the Ability of Violet Red Bile Glucose Agar to Detect Enterobacteriaceae
摘要
Violet red bile glucose agar（VRBGA，紫紅膽鹽葡萄糖瓊脂）為台灣衛生福利部食品藥物管理署最新公告「食品微生物之檢驗方法－腸桿菌科之檢驗」（以下簡稱公告方法）所使用之培養基。方法中，VRBGA係以煮沸後放置於47℃水浴，再利用傾注平板法與檢體混合，凝固後再進行第二次平板傾注。由於一般認為培養基配製的加熱時間或放置水浴時間的長短可能影響培養基分離細菌的能力，因此，VRBGA在100℃的過長加熱或重複加熱是否會影響腸桿菌科之分離能力有需要加以釐清。本研究利用大腸桿菌、沙門氏菌、克雷伯氏菌、金黃色葡萄球菌及綠膿桿菌的混合菌液做為檢體，研究VRBGA煮沸時間的長短（0－60分鐘）和次數（1－4次）以及47℃水浴放置時間長短（0－6小時）對腸桿菌科的分離能力是否會受到顯著影響。操作時，以小於100 CFU之混合菌液作為檢體，依照公告方法進行檢體的操作，將操作完成的VRBGA置於35±1℃的一般培養箱中培養24±2小時再進行判讀。結果顯示VRBGA腸桿菌科的分離能力並不受到煮沸時間和次數以及水浴放置時間的影響，此培養基的耐熱能力為品管檢驗室以其用作腸桿菌科檢驗的優點。
並列摘要
Violet red bile glucose agar (VRBGA) is a culture medium for enumeration of Enterobacteriaceae in foods recommended by the Food and Drug Administration (FDA) of the Taiwan Ministry of Health and Welfare. To prepare the medium, VRBGA powder is suspended in water and melted by boiling. The molten VRBGA is kept at 47℃ water bath and then poured onto plates to mix with the specimen. After solidification, each plate is overlaid with an appropriate amount of molten VRBGA. Since it is generally believed that over-heating can affect the efficacy of the culture medium, it is necessary to determine whether excessive or repeated heating of VRBGA at 100℃ will affect its isolation capability of Enterobacteriaceae. In this study, the boiling time (0-60 minutes) and frequency (1 to 4 times) and the duration of 47℃-keeping time (0-6 hours) of VRBGA were studied by using mixed bacterial suspension of Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, Staphylococcus aureus, and Pseudomonas aeruginosa as the test specimen. During the test, the mixed bacterial suspension containing less than 100 CFU was used as the specimen, and the plates were prepared as recommended. The VRBGA plates were then incubated in an ambient incubator at 35±1℃ for 24±2 hours. Results showed that the isolation capability of VRBGA was not affected by duration and frequency of boiling and length of 47℃-keeping time. Therefore, this heat resistance property of VRBGA is an advantage of using it to conduct Enterobacteriaceae test in foods.