Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061.
Appl Environ Microbiol. 1994 Mar;60(3):826-30. doi: 10.1128/aem.60.3.826-830.1994.
Two new methods for coliphage detection, a colorimetric agar-based (CAB) method and a liquid colorimetric presence-absence (LCPA) method, were compared to the coliphage method proposed by the American Public Health Association (APHA; Standard Methods for the Examination of Water and Wastewater, 18th ed., American Public Health Association, Washington, D.C., 1992). Both new methods are based on the induction of beta-galactosidase in Escherichia coli and the release of the enzyme through a lytic cell infection. The released enzyme then cleaves a chromogenic substrate which produces a colored reaction product. Ninety split water samples from four different sources were tested. A total of 52 samples were positive by the CAB method, 52 were positive by the LCPA method, and 53 were positive by the APHA method. Results indicated that (i) the CAB and LCPA methods were as sensitive in coliphage detection as the APHA method, (ii) both the CAB and LCPA methods were easier to read and interpret than the APHA method, and (iii) the CAB method detected more coliphages in a positive sample than the APHA method in two of the four types of water sources. Importantly, the rapid and simple LCPA method was as reliable and sensitive as either of the two agar-based methods in coliphage detection.
两种新的噬菌体检测方法,一种是基于比色琼脂的(CAB)方法,另一种是液体比色存在-不存在(LCPA)方法,与美国公共卫生协会(APHA)提出的噬菌体方法进行了比较(《水和废水的标准检验方法》,第 18 版,美国公共卫生协会,华盛顿特区,1992 年)。这两种新方法都是基于诱导大肠杆菌中的β-半乳糖苷酶和通过裂解细胞感染释放酶。释放的酶随后切割显色底物,产生有色反应产物。从四个不同来源中抽取了 90 个分离水样进行测试。共有 52 个样本用 CAB 方法呈阳性,52 个样本用 LCPA 方法呈阳性,53 个样本用 APHA 方法呈阳性。结果表明:(i)CAB 和 LCPA 方法在噬菌体检测中的灵敏度与 APHA 方法相同,(ii)CAB 和 LCPA 方法比 APHA 方法更容易阅读和解释,(iii)在四种水样中的两种水样中,CAB 方法在阳性样本中检测到的噬菌体比 APHA 方法多。重要的是,快速简单的 LCPA 方法在噬菌体检测中与两种琼脂方法一样可靠和敏感。