The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresi...The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.展开更多
Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municip...Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen （DO） of the reactor were 2 h and 4.2 mg. L 1, respectively. The reactor was agitated by a stirrer, with a speed of 250r·min^-1, to ensure good mixing . The granular sludge had good settleability, and the sludge volume index （SVI） was between 50 and 90 mL ·g ^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope （SEM） investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electro- phoresis （PCR-DGGE）. Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.展开更多
To understand the influence patterns and interactions of three important environmental factors,i.e.soil water content,oxygen concentration,and ammonium addition,on methane oxidation,the soils from landfill cover layer...To understand the influence patterns and interactions of three important environmental factors,i.e.soil water content,oxygen concentration,and ammonium addition,on methane oxidation,the soils from landfill cover layers were incubated under full factorial parameter settings.In addition to the methane oxidation rate,the quantities and community structures of methanotrophs were analyzed to determine the methane oxidation capacity of the soils.Canonical correspondence analysis was utilized to distinguish the important impact factors.Water content was found to be the most important factor influencing the methane oxidation rate and Type II methanotrophs,and the optimum value was 15%(w/w),which induced methane oxidation rates 10-and 6-times greater than those observed at 5%(w/w)and 20%(w/w),respectively.Ambient oxygen conditions were more suitable for methane oxidation than 3%oxygen.The addition of 100 mg-N·kg^(-1) drysoil of ammonium induced different effects on methane oxidation capacity when conducted at low or high water content.With regard to the methanotrophs,Type II was sensitive to the changes of water content,while Type I was influenced by oxygen content.Furthermore,the methanotrophic acidophile,Verrucomicrobia,was detected in soils with a pH of 4.9,which extended their known living environments.展开更多
Activated sludge was monthly sampled from a saline sewage treatment plant of Hong Kong(China)during June 2007 to May 2008 to analyze the microbial community shift along with environmental variations using denaturing g...Activated sludge was monthly sampled from a saline sewage treatment plant of Hong Kong(China)during June 2007 to May 2008 to analyze the microbial community shift along with environmental variations using denaturing gradient gel electrophoresis of polymerase chain reaction amplified 16S rDNA fragments.Environmental changes resulted into a seasonal microbial community shift characterized by alterations in species number and abundance in the sewage treatment plant.Correspondence analysis and cluster analysis on community structure profile showed that the 12 monthly samples fell into four groups,which is in accordance with season changing in Hong Kong.Canonical correspondence analysis revealed that PO_(4)^(3-)-P and NH_(4)^(+)-N posed more significant effects on community structure than total phosphorus and total nitrogen,respectively.Compared with sludge retention time,influent total phosphorus had an inverse effect on the community structure shift,and chemical oxygen demand and NH_(4)^(+)-N showed a similar effects.Results of this study may contribute to the development of new knowledge involving the microbial community shift in sewage treatment plants.展开更多
Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using sp...Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using specific primers F954 and R1369.Bright and reproducible bands were sequenced,and the phylogenic tree was constructed.The results show that the bacterial community composition changed between different seasons.The specific bands were different between the sampling sites with light and heavy levels of degraded grassland.Three main types of bacteria constituting the microbial community in the Inner Mongolia desert steppe belonged to the α,γ and δ-sub phyla of Proteobacteria,Bacteroidetes and Acidobacteria.The unculturable bacteria accounted for 69%of the whole bacterial community of the Inner Mongolia desert steppe.展开更多
基金supported by the Public Projects of Basic Research for Central-Level Research Institute in Chinese Research Academy of Environmental Sciences(No.2007KYYW24)the National Natural Science Foundation of China (No.50908220)
文摘The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.
基金Acknowledgements This research was supported by the National Natural Science Foundation of China （Grant No. 50878180）.
文摘Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen （DO） of the reactor were 2 h and 4.2 mg. L 1, respectively. The reactor was agitated by a stirrer, with a speed of 250r·min^-1, to ensure good mixing . The granular sludge had good settleability, and the sludge volume index （SVI） was between 50 and 90 mL ·g ^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope （SEM） investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electro- phoresis （PCR-DGGE）. Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.
基金This work was financially supported by the National Key Technology R&D Program of China(No.2006BAJ04A06)the National High-Tech Research and Development Program(863 Program)of China(No.2003AA644020).
文摘To understand the influence patterns and interactions of three important environmental factors,i.e.soil water content,oxygen concentration,and ammonium addition,on methane oxidation,the soils from landfill cover layers were incubated under full factorial parameter settings.In addition to the methane oxidation rate,the quantities and community structures of methanotrophs were analyzed to determine the methane oxidation capacity of the soils.Canonical correspondence analysis was utilized to distinguish the important impact factors.Water content was found to be the most important factor influencing the methane oxidation rate and Type II methanotrophs,and the optimum value was 15%(w/w),which induced methane oxidation rates 10-and 6-times greater than those observed at 5%(w/w)and 20%(w/w),respectively.Ambient oxygen conditions were more suitable for methane oxidation than 3%oxygen.The addition of 100 mg-N·kg^(-1) drysoil of ammonium induced different effects on methane oxidation capacity when conducted at low or high water content.With regard to the methanotrophs,Type II was sensitive to the changes of water content,while Type I was influenced by oxygen content.Furthermore,the methanotrophic acidophile,Verrucomicrobia,was detected in soils with a pH of 4.9,which extended their known living environments.
基金This research was supported by Hong Kong General Research Fund(HKU7195/06E)the authors would like to thank HKU Faculty of Engineering to support Dr.X.X.Zhang with the PostDoctoral Fellowship.
文摘Activated sludge was monthly sampled from a saline sewage treatment plant of Hong Kong(China)during June 2007 to May 2008 to analyze the microbial community shift along with environmental variations using denaturing gradient gel electrophoresis of polymerase chain reaction amplified 16S rDNA fragments.Environmental changes resulted into a seasonal microbial community shift characterized by alterations in species number and abundance in the sewage treatment plant.Correspondence analysis and cluster analysis on community structure profile showed that the 12 monthly samples fell into four groups,which is in accordance with season changing in Hong Kong.Canonical correspondence analysis revealed that PO_(4)^(3-)-P and NH_(4)^(+)-N posed more significant effects on community structure than total phosphorus and total nitrogen,respectively.Compared with sludge retention time,influent total phosphorus had an inverse effect on the community structure shift,and chemical oxygen demand and NH_(4)^(+)-N showed a similar effects.Results of this study may contribute to the development of new knowledge involving the microbial community shift in sewage treatment plants.
基金This work was supported by the National Natural Science Foundation of China(Grant No.30560030)the University Scientific Research Foundation of Inner Mongolia(No.NJ05099).
文摘Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using specific primers F954 and R1369.Bright and reproducible bands were sequenced,and the phylogenic tree was constructed.The results show that the bacterial community composition changed between different seasons.The specific bands were different between the sampling sites with light and heavy levels of degraded grassland.Three main types of bacteria constituting the microbial community in the Inner Mongolia desert steppe belonged to the α,γ and δ-sub phyla of Proteobacteria,Bacteroidetes and Acidobacteria.The unculturable bacteria accounted for 69%of the whole bacterial community of the Inner Mongolia desert steppe.
