Stability Analysis Of Microbial Pollution Indicators In The Pearl River Delta Region

As the increase of water environmental pollution control,people pay highly attention to non-point source pollution which caused by fecal discharge.Monitoring of fecal pollution has evolved from judge the pollution level to analyze the fecal source.Microbial source tracking is a kind of molecular biology,environmental microbiology and genetics as the foundation,through molecular and biochemical techniques,analyze the host-specific gene marker in environmental water that maybe contacted with some potential pollution sources to determine the source of fecal contamination.Due to the differences in climate,diet and lifestyle in different regions,there are some problems in the application of designed host-specific gene markers in target area.At the same time,the changes of host-specific markers in different environmental water bodies can also affect the accuracy of microbial source tracking.Therefore,it has a great significance to select suitable host-specific markers for different target areas and analyze their environmental behaviors under different external conditions.This study takes the Pearl River Delta region as the research area,identification of the suitable specific bacteroides primer for microbial source tracking.And through the water environmental simulation reactor to analyze the environmental behaviors of chicken-specific and human-specific primers in different DO concentration and nutrient level.Moreover,apply the microbial source tracking method to characterize the fecal pollution source and level.The main conclusions and results are as follows:(1)Human-specific marker qHB(1#),ruminant-specific marker qRB(5#),porcine-specific marker qPB(9#)and chicken-specific marker qCB(11#)showed high sensitivity and specificity in the Pearl River Delta region.Then,establish the standard curve of total bacteria primer(qTB),general bacteroides primer(qGB),escherichia coli primer(qEC)and specific markers which mentioned above,and confirmed that the qPCR technique is better than the conventional PCR method in the primer identification experiments.(2)Investigate the effects of dissolved oxygen and nutrient levels on the stability of host-specific markers.The decay rate of qGB,qCB and qHB was significantly faster in the aerobic environment than anaerobic environment.There was no significant effect of nutritional level on the change of microbial indicator bacteria,Escherichia coli,qGB,qCB and qHB showed the same trend in different nutrient levels.(3)In the actual water body simulation reactor,fecal coliform which detect by culture-method has significant correlationship with host-specific markers(p< 0.05),therefore,both of them can be used as indicator bacteria to evaluate the degree of microbial contamination in water body,but they have different characteristics.(4)The 14 sampling sites were all polluted at different levels by fecal pollution,the main sources of pollution were people,ruminants and chickens.The intensity of pollution by different source was found to be qHB>qRB>qCB,it reflects that the major contribute of pollutant source was human.