微生物污染源解析技术研究进展

针对目前新兴的微生物污染源解析技术（MST）研究进展进行了归纳总结.结果表明，标记物的源强特征显著影响水体微生物污染水平的评估，选用标记物时应同时考虑灵敏度和源强特征；与非目标物种样品产生交叉反应导致标记物特异性降低，可通过稀释样品或DNA纯化等手段降低假阳性信号强度；粪便源解析文库（FTL）中应涵盖的宿主种类，以及每类宿主应纳入的个体数量均会影响建库源解析结果的准确性，可通过权重分析来确定源文库中各宿主应囊括的样本量，提高识别污染源的准确性；FTL中的物种与土著微生物分类较为接近时，SourceTracker难以准确区分微生物污染来源，将土著微生物信息纳入FTL并多次运行程序可提高SourceTracker识别污染源的能力.未来应加强对标记物灵敏度和源强特征之间相关关系的研究，同时探讨标记物源强特征产生差异的成因以及交叉反应产生的机理；另一方面，应深入探究粪源微生物种内变异程度和土著微生物的种类对建库源解析法的影响机制，以期建立准确、完善的微生物污染源解析技术.

Advances in microbial source tracking methods

This review summarized various detection methods of microbial source tracking (MST) in recent publications and the results showed as follow. Firstly, marker abundance significantly affects the risk assessment of microbial contamination in water. Thus we should consider both of sensitivity and abundance when selecting suitable markers. Meanwhile, the cross-reaction between non-target samples and markers may decrease the specificity of suitable markers and we could dilute the sample or purify the DNA to avoid this issue. Moreover, an important consideration with library-dependent MST assays is to determine the appropriate fecal taxon libraries (FTL) size of samples for each host, which can be accomplished by using power analysis. In addition, SourceTracker is difficult to distinguish the source of microbial contamination accurately when the species in the FTL are closer to the autochthonous taxa. This issue could be improved by incorporating autochthonous taxa in the FTL and increasing the number of model runs. To overcome these barriers and establish accurate and comprehensive MST methods, this study proposed to: 1) explore the relationship between sensitivity and abundance of selected markers and clarify the causes of the differences among marker abundances; 2) enhance the understanding of cross-reaction between non-target samples and markers; 3) verify the influence mechanism of the intragroup variability among fecal microorganisms and the types of autochthonous taxa on library-dependent MST method.