The quantification of pathogens is important for assessing water safety and preventing disease outbreaks. Culture-independent approaches, such as quantitative PCR (qPCR) and digital PCR (dPCR), are useful techniques for quantifying pathogens in water samples. However, since pathogens are usually present at low concentrations in water, it is necessary to concentrate microbial cells before extracting their DNA. Many existing microbial concentration methods are inefficient or take a long time to perform. In this study, we applied a coagulation and foam separation method to concentrate environmental water samples of between 1000 and 5000 mL to 100 μL of DNA (i.e., a 1–5 × 10⁴-fold concentration). The concentration process took <1 h. The DNA samples were then used to quantify various target pathogens using dPCR. One gene, the Shiga toxin gene (stx₂) of Shiga toxin-producing Escherichia coli, was detected at 32 copies/100 mL in a river water sample. The coagulation and foam concentration method followed by dPCR reported herein is a fast, sensitive, and reliable method to quantify pathogen genes in environmental water samples.

病原体的量化对于评估水安全和预防疾病暴发非常重要。与文化无关的方法，例如定量PCR（qPCR）和数字PCR（dPCR），是定量水样品中病原体的有用技术。但是，由于病原体通常以低浓度存在于水中，因此有必要在提取微生物细胞之前先浓缩微生物细胞。许多现有的微生物浓缩方法效率低下或执行时间长。在这项研究中，我们采用了一种凝结和泡沫分离方法，将1000至5000 mL的环境水样品浓缩到100μLDNA（即1-5×10 ⁴倍浓度）。浓缩过程花费了不到1小时。然后使用dPCR将DNA样品用于量化各种靶标病原体。在河水样品中检测到一个基因，即产生志贺毒素的大肠杆菌的志贺毒素基因（stx ₂），为32拷贝/ 100 mL。本文报道的凝结和泡沫浓缩方法以及随后的dPCR是定量环境水样品中病原体基因的快速，灵敏和可靠的方法。