Wu Jianyong, Stewart Jill R, Sobsey Mark D, Cormency Chris, Fisher Michael B, Bartram Jamie K
Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The Water Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
Water, Sanitation and Education Center, UNICEF Supply Division, Nordhavn, 2150, Copenhagen, Denmark.
Curr Microbiol. 2018 Jul;75(7):827-834. doi: 10.1007/s00284-018-1454-8. Epub 2018 Feb 21.
Methods for rapid detection of fecal indicator bacteria in water are important to ensure that water is safe for drinking, bathing, recreation, fishing and shellfish harvesting. In this study, we tested experimental conditions for bacterial hydrolysis of two promising enzymatic substrates, 5-Bromo-4-chloro-3-indolyl β-D-glucuronide (X-Gluc) and Resorufin β-D-glucuronide (REG), and optimized parameters such as temperature and pH to determine conditions for rapid reactions. We then innovated a membrane filter-based approach to facilitate more rapid enzyme-based detection of Escherichia coli in water based on the combination of an initial concentration step and optimized test conditions. For this approach, a water sample (10‒100 mL) is filtered through a 0.45-µm pore size filter with a diameter of 4 or 13 mm. After filtration, a newly designed rapid detection broth is added containing the enzymatic inducer Methyl-beta-D-Glucuronide sodium (MetGlu) and the substrate REG or X-Gluc. After a few (1‒7) hours of incubation at 35 °C, the filter shows pink color (for REG-containing broth) or green color (for X-Gluc containing broth) if E. coli is present. The study provides insights and approaches towards developing a simple, fast, and low-cost method to detect fecal indicator bacteria in water.
快速检测水中粪便指示菌的方法对于确保水在饮用、洗浴、娱乐、捕鱼和贝类捕捞方面的安全性至关重要。在本研究中，我们测试了两种有前景的酶底物5-溴-4-氯-3-吲哚基β-D-葡萄糖醛酸苷（X-Gluc）和试卤灵β-D-葡萄糖醛酸苷（REG）的细菌水解实验条件，并优化了温度和pH等参数以确定快速反应的条件。然后，我们创新了一种基于膜过滤的方法，通过结合初始浓缩步骤和优化的测试条件，促进更快速地基于酶检测水中的大肠杆菌。对于这种方法，将水样（10-100 mL）通过孔径为0.45 µm、直径为4或13 mm的滤膜过滤。过滤后，加入新设计的快速检测肉汤，其中含有酶诱导剂甲基-β-D-葡萄糖醛酸钠（MetGlu）和底物REG或X-Gluc。在35°C孵育数小时（1-7小时）后，如果存在大肠杆菌，滤膜会呈现粉红色（对于含REG的肉汤）或绿色（对于含X-Gluc的肉汤）。该研究为开发一种简单、快速且低成本的水中粪便指示菌检测方法提供了见解和方法。
