Xiong Zirui Ray, Brooks Ajani A, Gabriel Ellen, Gutierrez Alan, Johnson Shayla B, East Cheryl, Durso Lisa M, Moss Elica, Sharma Manan
United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Environmental Microbial and Food Safety Laboratory, Beltsville, MD, United States of America.
Department of Animal and Food Sciences, University of Delaware, Newark, DE, United States of America.
BMC Res Notes. 2025 Aug 20;18(1):365. doi: 10.1186/s13104-025-07423-9.
Membrane filtration and Colilert assays are commonly used to quantify Escherichia coli levels in agricultural water. These methods have not been evaluated in test agricultural water (TAW), a formulation used for assessing chemical sanitizer effectiveness. Quantitative recovery of E. coli in TAW may be affected by turbidity levels. TAW was formulated with a pH value of 6.5 at two turbidity levels (0 and 50 NTU). Pan-susceptible and cefotaxime-resistant E. coli strains were added separately to TAW (200 CFU/100 mL). Inoculated TAW was either (1) filtered using a 0.45 μm membrane filter (MF) and placed onto Tryptone Bile X-Glucuronide (TBX) agar or CHROMagar ECC (ECC), or (2) tested by IDEXX Quanti-Tray/2000 Colilert. Recovery percentages of E. coli at both turbidity levels were similar on TBX and ECC, but pan-susceptible E. coli ARS C101 in TAW at 50 NTU on TBX was not quantifiable. For Colilert assays, the recovery percentages of E. coli from 0 NTU and 50 NTU TAW were between 93.4 ± 4.4% and 127.0 ± 10.5%. Overall, ECC and Colilert provided quantifiable results for recovery of pan-susceptible and cefotaxime-resistant E. coli from artificial agricultural water at different turbidity levels. Higher levels of turbidity affected the ability to quantify E. coli by MF with TBX and recovery by Colilert.
膜过滤法和Colilert检测法常用于定量分析农业用水中的大肠杆菌含量。这些方法尚未在测试农业用水（TAW）中进行评估，TAW是一种用于评估化学消毒剂有效性的制剂。TAW中大肠杆菌的定量回收率可能受浊度水平影响。TAW在两种浊度水平（0和50 NTU）下配制，pH值为6.5。将泛敏感和耐头孢噻肟的大肠杆菌菌株分别添加到TAW中（200 CFU/100 mL）。接种后的TAW要么（1）使用0.45μm的膜过滤器（MF）过滤，然后置于胰蛋白胨胆盐X-葡糖醛酸苷（TBX）琼脂或CHROMagar ECC（ECC）上，要么（2）通过IDEXX Quanti-Tray/2000 Colilert进行检测。在TBX和ECC上，两种浊度水平下大肠杆菌的回收率相似，但在50 NTU的TAW中，TBX上的泛敏感大肠杆菌ARS C101无法定量。对于Colilert检测，0 NTU和50 NTU的TAW中大肠杆菌的回收率在93.4±4.4%至127.0±10.5%之间。总体而言，ECC和Colilert为从不同浊度水平的人工农业用水中回收泛敏感和耐头孢噻肟的大肠杆菌提供了可量化的结果。较高的浊度水平影响了用TBX通过MF定量大肠杆菌的能力以及Colilert的回收率。
