Detection Of Enteric Bacteria From Surface Waters By QPCR And Analysis Of Pathogenic Bacteria Pollution Characteristic

To study the pathogenic pollution characteristic of the surface water,we chose five water body including a source water for drinking water supply(Heihe River),two landscape lake(Beihu Lake and Xingqing Lake),a water source receiving industrial discharge(Chanhe River)and a secondary effluent(Beishiqiao Wastewater Treatment Plant)during March to July 2007.Samples were collected consecutively about five monthes.The DNA of bacteria from the five water bodies were extracted and then amplified with the universal primers.As a compare,the total bacteria,coliforms and faecal coliforms were detected by membrane filtration(MF)method simultaneously.A rapid quantitative polymerase chain reaction(QPCR)analysis method with universal primers was developed to detect cell densities of the Salmonella typhrmurium, Shigella dysenteriae,Vibrio cholerae,and Eseherichia coli.simultaniously.What's more,the accurate and sensitive measurements of these organisms can be obtained within 5 hours.It provides a more reliable approach for the assessment of bacteriological risk of water environment.Measurements by QPCR method were compared with counts of total bacteria,total coliforms,and fecal coliforms colony-forming units(CFU)determined by membrane filter(MF)analysis.The geometric mean of pathogenic bacteria concentration determined by total bacteria from the five surface waters(N=55)was 7～9 times of QPCR.Geometric means of pathogenic bacteria concentration determined by total bacteria by MF method ranged from 1.1×10⁴～9.8×10⁷ CFU·100mL^-1(N=55),QPCR method ranged from 1.2×10³ï½ž1.3×10⁷ CCE·100mL^-1.The detection results by QPCR method were compared with counts of coliforms colony-forming units(CFU) determined by membrane filter(MF)analysis.Regression analyses and statistical comparisons of the MF culture and QPCR results showed that a positive correlation between the QPCR and total bacteria with a strong correlation coefficient(r=0.86)can be seen.It also showed that a correlation,between the QPCR and coliforms,faecal coliforms(r＞0.5).Regarding different water samples,Hei He River of high quality as source water reached the Gradeâ… surface water standard and QPCR results reached the Gradeâ…¢surface water standard;Bei Hu and Xing Qing Lake could reach the Gradeâ… and Gradeâ…¡surface water quality standard differently;Chan He River reached the Gradeâ…¤surface water standard,however,a very high QPCR may indicate the existence of large numbers of other pathogenic bacteria;The secondary effluent without disinfection was of high concentration of fecal coliform(beyond the Gradeâ…¤)and much higher concentration of other pathogenic bacteria according to QPCR results.The current guidelines,based on MF results were unlikely to be applicable to QPCR results. More and Long-term researches should be put in practice,If we adopt QPCR method for the assessment of bacteriological risk of water environment.