Walters Sarah P, Field Katharine G
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA.
Environ Microbiol. 2009 Jun;11(6):1410-21. doi: 10.1111/j.1462-2920.2009.01868.x. Epub 2009 Apr 23.
Amplification of host-specific markers from Bacteroidales faecal anaerobes can rapidly identify the source of faecal pollution. It is necessary to understand persistence and survival of these markers and marker cells, both to interpret quantitative source-tracking data, and to use such data to predict pathogen occurrence. We measured marker persistence and cell survival of two human (HF134, HF183) and two ruminant (CF128, CF193) faecal Bacteroidales markers, compared with Escherichia coli and enterococci. Freshwater microcosms were inoculated with fresh cattle or human faeces and incubated at 13 degrees C in natural light or darkness. Marker persistence was measured by polymerase chain reaction (PCR) and quantitative PCR. Survival of marker cells was measured by real-time quantitative PCR. There was no difference in persistence between the two human-specific Bacteroidales DNA markers in the light and dark microcosms. Cell survival profiles of the two human markers were also similar; both were significantly affected by light. Ruminant markers persisted and survived longer than human markers (14 versus 6 days respectively). CF193 decreased more rapidly than CF128, and light significantly affected CF128 but not CF193. These results support use of host-specific faecal Bacteroidales markers as indicators of recent faecal pollution, but suggest that caution is needed in interpreting quantitative results to indicate proportional contribution of different sources, as individual markers differ in their survival, persistence and response to environmental variables. The survival and persistence profiles for Bacteroidales markers are consistent with survival profiles for several faecal pathogens.
从粪便拟杆菌中扩增宿主特异性标记物可以快速识别粪便污染的来源。了解这些标记物和标记细胞的持久性和存活情况,对于解释定量溯源数据以及利用此类数据预测病原体的出现都很有必要。我们测量了两种人类(HF134、HF183)和两种反刍动物(CF128、CF193)粪便拟杆菌标记物的标记物持久性和细胞存活情况,并与大肠杆菌和肠球菌进行了比较。用新鲜牛粪或人粪接种淡水微型生态系统,并在13摄氏度的自然光或黑暗条件下孵育。通过聚合酶链反应(PCR)和定量PCR测量标记物持久性。通过实时定量PCR测量标记细胞的存活情况。在光照和黑暗微型生态系统中,两种人类特异性拟杆菌DNA标记物的持久性没有差异。两种人类标记物的细胞存活情况也相似;两者均受到光照的显著影响。反刍动物标记物的持久性和存活时间比人类标记物更长(分别为14天和6天)。CF193的下降速度比CF128更快,光照显著影响CF128,但不影响CF193。这些结果支持将宿主特异性粪便拟杆菌标记物用作近期粪便污染的指标,但表明在解释定量结果以表明不同来源的比例贡献时需要谨慎,因为各个标记物在存活、持久性和对环境变量的反应方面存在差异。拟杆菌标记物的存活和持久性情况与几种粪便病原体的存活情况一致。