Scientifically sound methods to rapidly measure fecal indicator bacteria are important to ensure safe water for drinking and recreational purposes.A total of 200 water samples obtained from the Three Gorges Reservoir ...Scientifically sound methods to rapidly measure fecal indicator bacteria are important to ensure safe water for drinking and recreational purposes.A total of 200 water samples obtained from the Three Gorges Reservoir during three successive one-year study periods（October 2009 to September 2012） were analyzed using multiple-tube fermentation（MTF）and most probable numbers combined with polymerase chain reaction（MPN-PCR）.The MPN-PCR method was found to be significantly more sensitive than the MTF method for detecting Escherichia coli and Enterococcus spp.,and of equal sensitivity for detecting total coliforms when all surface water samples were grouped together.The two analytical methods had a strong,significant relationship,but MPN-PCR took only 12-18 hr,compared with the 3-8 days needed using the MTF method.Bacterial concentrations varied per sampling site but were significantly lower in the mainstream of the Yangtze River than those in the backwater areas of tributaries.The water quality of 85.8% of water samples from the mainstream was suitable for use as a centralized potable water source,while the water quality of 52.5% of water samples from the backwater areas was unsuitable for recreational activities.Relationships between fecal indicator bacteria showed significant correlation（r = 0.636-0.909,p 〈 0.01,n = 200）,while a weak but significant correlation was found between fecal indicators and water turbidity,water temperature,daily inflow,and total dissolved solids（r = 0.237-0.532,p 〈 0.05,n = 200）.The study indicated that MPN-PCR is a rapid and easily performed deoxyribonucleic acid（DNA）-based method for quantitative detection of viable total coliforms,E.coli,and Enterococcus spp.in surface water.展开更多
To improve nitrogen removal performance of wastewater treatment plants （WWTPs）, it is essential to understand the behavior of nitrogen cycling communities, which comprise various microorganisms. This study character...To improve nitrogen removal performance of wastewater treatment plants （WWTPs）, it is essential to understand the behavior of nitrogen cycling communities, which comprise various microorganisms. This study characterized the quantity and diversity of nitrogen cycling genes in various processes of municipal WWTPs by employing two molecular-based methods：most probable number-polymerase chain reaction （MPN-PCR） and DNA microarray. MPN-PCR analysis revealed that gene quantities were not statistically different among processes, suggesting that conventional actwated sludge processes （CAS） are similar to nitrogen removal processes in their ability to retain an adequate population of nitrogen cycling microorganisms. Furthermore, most processes in the WWTPs that were researched shared a pattern：the nitS and the bacterial amoA genes were more abundant than the nirK and archaeal amoA genes, respectivelv. DNA microarray analysis revealed that several kinds of nitrification and denitrification genes were detected in both CAS and anaerobic-oxic processes （AO）, whereas limited genes were detected in nitrogen removal processes. Results of this study suggest that CAS maintains a diverse community of nitrogen cycling microorganisms; moreover, the microbial communities in nitrogen removal processes may be specific.展开更多
基金supported by the Basic and Advanced Research Project of Chongqing CSTC (No.cstc2013jcyj A20011)the Special Foundation for Scientific and Technological Talents of Wanzhou District of Chongqing Province,China
文摘Scientifically sound methods to rapidly measure fecal indicator bacteria are important to ensure safe water for drinking and recreational purposes.A total of 200 water samples obtained from the Three Gorges Reservoir during three successive one-year study periods（October 2009 to September 2012） were analyzed using multiple-tube fermentation（MTF）and most probable numbers combined with polymerase chain reaction（MPN-PCR）.The MPN-PCR method was found to be significantly more sensitive than the MTF method for detecting Escherichia coli and Enterococcus spp.,and of equal sensitivity for detecting total coliforms when all surface water samples were grouped together.The two analytical methods had a strong,significant relationship,but MPN-PCR took only 12-18 hr,compared with the 3-8 days needed using the MTF method.Bacterial concentrations varied per sampling site but were significantly lower in the mainstream of the Yangtze River than those in the backwater areas of tributaries.The water quality of 85.8% of water samples from the mainstream was suitable for use as a centralized potable water source,while the water quality of 52.5% of water samples from the backwater areas was unsuitable for recreational activities.Relationships between fecal indicator bacteria showed significant correlation（r = 0.636-0.909,p 〈 0.01,n = 200）,while a weak but significant correlation was found between fecal indicators and water turbidity,water temperature,daily inflow,and total dissolved solids（r = 0.237-0.532,p 〈 0.05,n = 200）.The study indicated that MPN-PCR is a rapid and easily performed deoxyribonucleic acid（DNA）-based method for quantitative detection of viable total coliforms,E.coli,and Enterococcus spp.in surface water.
文摘To improve nitrogen removal performance of wastewater treatment plants （WWTPs）, it is essential to understand the behavior of nitrogen cycling communities, which comprise various microorganisms. This study characterized the quantity and diversity of nitrogen cycling genes in various processes of municipal WWTPs by employing two molecular-based methods：most probable number-polymerase chain reaction （MPN-PCR） and DNA microarray. MPN-PCR analysis revealed that gene quantities were not statistically different among processes, suggesting that conventional actwated sludge processes （CAS） are similar to nitrogen removal processes in their ability to retain an adequate population of nitrogen cycling microorganisms. Furthermore, most processes in the WWTPs that were researched shared a pattern：the nitS and the bacterial amoA genes were more abundant than the nirK and archaeal amoA genes, respectivelv. DNA microarray analysis revealed that several kinds of nitrification and denitrification genes were detected in both CAS and anaerobic-oxic processes （AO）, whereas limited genes were detected in nitrogen removal processes. Results of this study suggest that CAS maintains a diverse community of nitrogen cycling microorganisms; moreover, the microbial communities in nitrogen removal processes may be specific.
