Sresung Montakarn, Paisantham Phongsawat, Ruksakul Pacharaporn, Kongprajug Akechai, Chyerochana Natcha, Gallage Tharindu Pollwatta, Srathongneam Thitima, Rattanakul Surapong, Maneein Siriwara, Surasen Chatsinee, Passananon Somsak, Mongkolsuk Skorn, Sirikanchana Kwanrawee
Research Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand.
Program in Environmental Toxicology, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok 10210, Thailand.
Sci Total Environ. 2023 Jun 10;876:162689. doi: 10.1016/j.scitotenv.2023.162689. Epub 2023 Mar 9.
Microbial contamination deteriorates source water quality, posing a severe problem for drinking water suppliers worldwide and addressed by the Water Safety Plan framework to ensure high-quality and reliable drinking water. Microbial source tracking (MST) is used to examine different microbial pollution sources via host-specific intestinal markers for humans and different types of animals. However, the application of MST in tropical surface water catchments that provide raw water for drinking water supplies is limited. We analyzed a set of MST markers, namely, three cultivable bacteriophages and four molecular PCR and qPCR assays, together with 17 microbial and physicochemical parameters, to identify fecal pollution from general, human-, swine-, and cattle-specific sources. Seventy-two river water samples at six sampling sites were collected over 12 sampling events during wet and dry seasons. We found persistent fecal contamination via the general fecal marker GenBac3 (100 % detection; 2.10-5.42 log copies/100 mL), with humans (crAssphage; 74 % detection; 1.62-3.81 log copies/100 mL) and swine (Pig-2-Bac; 25 % detection; 1.92-2.91 log copies/100 mL). Higher contamination levels were observed during the wet season (p < 0.05). The conventional PCR screening used for the general and human markers showed 94.4 % and 69.8 % agreement with the respective qPCR results. Specifically, in the studied watershed, coliphage could be a screening parameter for the crAssphage marker (90.6 % and 73.7 % positive and negative predictive values; Spearman's rank correlation coefficient = 0.66; p < 0.001). The likelihood of detecting the crAssphage marker significantly increased when total and fecal coliforms exceeded 20,000 and 4000 MPN/100 mL, respectively, as Thailand Surface Water Quality Standards, with odds ratios and 95 % confidence intervals of 15.75 (4.43-55.98) and 5.65 (1.39-23.05). Our study confirms the potential benefits of incorporating MST monitoring into water safety plans, supporting the use of this approach to ensure high-quality drinking water supplies worldwide.
微生物污染会使源水水质恶化，给全球饮用水供应商带来严重问题，而《水安全计划》框架可解决这一问题，以确保提供高质量且可靠的饮用水。微生物源追踪（MST）用于通过针对人类和不同类型动物的宿主特异性肠道标志物来检测不同的微生物污染源。然而，MST在为饮用水供应提供原水的热带地表水集水区中的应用有限。我们分析了一组MST标志物，即三种可培养噬菌体以及四种分子PCR和qPCR检测方法，同时分析了17种微生物和理化参数，以识别来自一般、人类、猪和牛特定来源的粪便污染。在雨季和旱季的12次采样活动中，在六个采样点采集了72份河水样本。我们发现通过一般粪便标志物GenBac3存在持续性粪便污染（检测率100%；2.10 - 5.42 log拷贝数/100 mL），还有来自人类（crAssphage；检测率74%；1.62 - 3.81 log拷贝数/100 mL）和猪（Pig - 2 - Bac；检测率25%；1.92 - 2.91 log拷贝数/100 mL）的污染。在雨季观察到更高的污染水平（p < 0.05）。用于一般和人类标志物的常规PCR筛查与各自的qPCR结果的一致性分别为94.4%和69.8%。具体而言，在所研究的流域中，大肠杆菌噬菌体可能是crAssphage标志物的一个筛查参数（阳性和阴性预测值分别为9则为0.66；p < 0.001）。当总大肠菌群和粪大肠菌群分别超过泰国地表水水质标准的20000和4000 MPN/100 mL时，检测到crAssphage标志物的可能性显著增加，优势比和95%置信区间分别为15.75（4.43 - 55.98）和5.65（1.39 - 23.05）。我们的研究证实了将MST监测纳入水安全计划的潜在益处，支持采用这种方法来确保全球高质量的饮用水供应。
