Research Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand.
Applied Biological Sciences, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok, 10210, Thailand.
Int J Hyg Environ Health. 2020 May;226:113482. doi: 10.1016/j.ijheh.2020.113482. Epub 2020 Feb 19.
The bacteriophages of E. faecalis strains AIM06 (DSM100702) and SR14 (DSM100701) have previously been validated as human-specific microbial source tracking (MST) markers in Thailand. In this study, their spatial and temporal distribution in a freshwater river was investigated for the first time (n = 48). The abundance of enterococci as a standard microbial water quality parameter was evaluated by both the qPCR detection assay with primers and a hydrolysis probe according to the US EPA Method 1611 and the US EPA Method 1600 membrane filtration culture method. AIM06 and SR14 phages were detected by a double layer agar assay and were present in 87.5% and 81.3% of all samples with a co-presence of 92.9% of phage-positive samples. After spiking the representative phages, the ranges of recovery efficiencies were 57.9-99.6% and 49.6-99.9% (n = 48) for AIM06 and SR14 phages, respectively. The absolute abundance of AIM06 and SR14 phages ranged from 0.25 to 221.94 and from 0.25 to 76.66 PFU/100 mL, respectively. Enterococci DNA copies and CFU were detected in all samples ranging from 3.24 to 6.32 log10 copies/100 mL and 100.00 to 1593 CFU/100 mL, respectively. Enterococci in the qPCR assay also showed a moderate correlation with the culture method. The AIM06 and SR14 phage results indicated continuing human faecal pollution along the river with no significant different levels among stations. Interestingly, the higher levels of enterococci in downstream stations for both the qPCR and culture methods along with the significant correlation with other faecal indicator organisms and non-human MST markers implied non-human faecal pollution. In conclusion, this study provides insightful information that could lead to effective water quality management and public health risk reduction from exposure to faecally-contaminated water.
先前，屎肠球菌菌株 AIM06（DSM100702）和 SR14（DSM100701）的噬菌体已被验证为泰国的人类特异性微生物源追踪（MST）标志物。本研究首次对其在淡水河中的时空分布进行了调查（n=48）。通过 US EPA Method 1611 和 US EPA Method 1600 膜过滤培养法中的引物和水解探针 qPCR 检测法评估了 enterococci 作为标准微生物水质参数的丰度。使用双层琼脂测定法检测 AIM06 和 SR14 噬菌体，阳性样品的共同存在率为 92.9%，所有样品中噬菌体阳性率为 87.5%和 81.3%。在代表噬菌体接种后，AIM06 和 SR14 噬菌体的回收率范围分别为 57.9-99.6%和 49.6-99.9%（n=48）。AIM06 和 SR14 噬菌体的绝对丰度范围分别为 0.25-221.94 和 0.25-76.66 PFU/100 mL。所有样品中均检测到 enterococci DNA 拷贝数和 CFU，范围分别为 3.24-6.32 log10 拷贝/100 mL 和 100.00-1593 CFU/100 mL。qPCR 检测中的 enterococci 与培养方法也呈中度相关。AIM06 和 SR14 噬菌体的结果表明，河流沿线仍存在持续的人类粪便污染，各站位之间没有明显的水平差异。有趣的是，下游站位的 enterococci 水平较高，qPCR 和培养方法均如此，且与其他粪便指示生物和非人类 MST 标志物显著相关，暗示存在非人类粪便污染。总之，本研究提供了有见地的信息，可有助于有效管理水质和降低因接触粪便污染水而导致的公共健康风险。
