Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for comple...Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for completely autotrophic nitrogen removal over nitrite （CANON）. Fed with synthetic wastewater rich in ammo- nia, the SBR removed 82.54-5.4% ofinfluent nitrogen and a maximum nitrogen-removal rate of 0.52kgN.m 3.d-l was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria （AerAOB） Nitrosomonas and anaerobic ammonium-oxidizing bacteria （AnAOB） dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen （DO）, NH＋, NO＋ and NO3 microelectrodes. In the outer layer of sludge aggregates （0-700 μm）, nitrite-oxidizing bacteria （NOB） showed high activity with 4.1 gmol-cm3＋ h-1 of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg. L 1. Maximum AerAOB activity was detected in the middle layer （depths around 1700 μm） where DO concentration was 1.1 μg. L-1. In the inner layer （2200-3500μm）, where DO concentration was below 0.9 mg. L-1, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.展开更多
Nitrite accumulation in shrimp ponds can pose serious adverse effects to shrimp production and the environment.This study aims to develop an effective process for the enrichment of ready-to-use nitrite-oxidizing bacte...Nitrite accumulation in shrimp ponds can pose serious adverse effects to shrimp production and the environment.This study aims to develop an effective process for the enrichment of ready-to-use nitrite-oxidizing bacteria（NOB）inocula that would be appropriate for nitrite removal in brackish shrimp ponds.To achieve this objective,the effects of nitrite concentrations on NOB communities and nitrite oxidation kinetics in a brackish environment were investigated.Moving-bed biofilm sequencing batch reactors and continuous moving-bed biofilm reactors were used for the enrichment of NOB at various nitrite concentrations,using sediment from brackish shrimp ponds as seed inoculum.The results from NOB population analysis with quantitative polymerase chain reaction（q PCR）show that only Nitrospira were detected in the sediment from the shrimp ponds.After the enrichment,both Nitrospira and Nitrobacter coexisted in the reactors controlling effluent nitrite at 0.1 and 0.5 mg-NO2^--N/L.On the other hand,in the reactors controlling effluent nitrite at 3,20,and 100 mg-NO2^--N/L,Nitrobacter outcompeted Nitrospira in many orders of magnitude.The half saturation coefficients（Ks）for nitrite oxidation of the enrichments at low nitrite concentrations（0.1 and 0.5 mg-NO2^--N/L）were in the range of 0.71–0.98 mg-NO2^--N/L.In contrast,the Ksvalues of NOB enriched at high nitrite concentrations（3,20,and 100 mg-NO2^--N/L）were much higher（8.36–12.20 mg-NO2^--N/L）.The results suggest that the selection of nitrite concentrations for the enrichment of NOB inocula can significantly influence NOB populations and kinetics,which could affect the effectiveness of their applications in brackish shrimp ponds.展开更多
The effects of chitosan characteristics including the degree of deacetylation, molecular weight, particle size, pH pretreatment and immobilization time on the immobilization of nitrite-oxidizing bacteria （NOB） on bi...The effects of chitosan characteristics including the degree of deacetylation, molecular weight, particle size, pH pretreatment and immobilization time on the immobilization of nitrite-oxidizing bacteria （NOB） on biopolymeric chitosan were investigated. Nitrite removal efficiency of immobilized NOB depended on the degree of deacetylation, particle size, pH pretreatment on the surface of chitosan and immobilization time. Scanning electron microscope characterization illustrated that the number of NOB cells attached to the surface of chitosan increased with an increment of immobilization time. The optimal condition for NOB immobilization on chitosan was achieved during a 24-hr immobilization period using chitosan with the degree of deacetylation larger than 80% and various particle size ranges between 1-5 mm at pH 6.5. In general, the NOB immobilized on chitosan flakes has a high potential to remove excess nitrite from wastewater and aquaculture systems.展开更多
Nitrate (NO-3) and nitrite (NO2-) leaching threatens groundwater quality.Soil C:N ratio,i.e.,the ratio of soil organic carbon to total nitrogen,affects mineralization,nitrification,and denitrification;however,its mech...Nitrate (NO-3) and nitrite (NO2-) leaching threatens groundwater quality.Soil C:N ratio,i.e.,the ratio of soil organic carbon to total nitrogen,affects mineralization,nitrification,and denitrification;however,its mechanism for driving soil NO-3and NO-2accumulation and leaching remains unclear.Here,a field investigation in a fluvo-aquic soil and a soil column experiment were performed to explore the relationships between soil C:N ratio and soil NO-3and NO-2leaching in three soil layers (0–20,20–40,and 40–60 cm) under heavy rainfall (rainfall rate>25 mm d-1).The field investigation results showed that both soil NO-3-N and NO-2-N contents decreased exponentially (P<0.001) with increasing soil C:N ratio in each soil layer.Furthermore,negative exponential relationships (P<0.001) were found between soil C:N ratio and both NO-3-N and NO-2-N concentrations in soil solution in each soil layer under heavy rainfall.The soil column divided into three layers was leached with simulated heavy rainfall;the results confirmed negative exponential relationships (P<0.05) between soil C:N ratio and both NO-3-N and NO-2-N concentrations in the leachate from each soil layer.A total of 18 soil samples obtained from three depths at six field sites during the rainy season were used to elucidate the microbial mechanisms induced by soil C:N ratio using high-throughput sequencing and real-time polymerase chain reaction.High abundances of ammonifying bacteria (Flavobacterium,Bacillu,and Pseudomonas),ammonia-oxidizing bacteria (Nitrosospira),and nirS/K gene were observed when soil C:N was low,concomitant with low abundances of NO-2-oxidizing bacteria (Nitrospira) and narG gene.Partial least squares path modeling showed that the high NO-3and NO-2levels at low soil C:N ratio might be attributed to the inhibition of NO-3reduction (i.e.,low narG gene) and NO-2oxidation (i.e.,low Nitrospira) and thus the accumulation of soil NO-3and NO-2,respectively.Therefore,the leaching of NO-2and NO-3in low C:N soils requires more attention during the rai展开更多
Long-term nitrogen(N)fertilization imposes strong selection on nitrifying communities in agricultural soil,but how a progressively changing niche affects potentially active nitrifiers in the field remains poorly under...Long-term nitrogen(N)fertilization imposes strong selection on nitrifying communities in agricultural soil,but how a progressively changing niche affects potentially active nitrifiers in the field remains poorly understood.Using a 44-year grassland fertilization experiment,we investigated community shifts of active nitrifiers by DNA-based stable isotope probing(SIP)of field soils that received no fertilization(CK),high levels of organic cattle manure(HC),and chemical N fertilization(CF).Incubation of DNA-SIP microcosms showed significant nitrification activities in CF and HC soils,whereas no activity occurred in CK soils.The 44 years of inorganic N fertilization selected only 13C-ammonia-oxidizing bacteria(AOB),whereas cattle slurry applications created a niche in which both ammonia-oxidizing archaea(AOA)and AOB could be actively13C-labeled.Phylogenetic analysis indicated that Nitrosospira sp.62-like AOB dominated inorganically fertilized CF soils,while Nitrosospira sp.41-like AOB were abundant in organically fertilized HC soils.The 13C-AOA in HC soils were affiliated with the 29i4 lineage.The 13C-nitrite-oxidizing bacteria(NOB)were dominated by both Nitrospira-and Nitrobacter-like communities in CF soils,and the latter was overwhelmingly abundant in HC soils.The 13C-labeled nitrifying communities in SIP microcosms of CF and HC soils were largely similar to those predominant under field conditions.These results provide direct evidence for a strong selection of distinctly active nitrifiers after 44 years of different fertilization regimes in the field.Our findings imply that niche differentiation of nitrifying communities could be assessed as a net result of microbial adaption over 44 years to inorganic and organic N fertilization in the field,where distinct nitrifiers have been shaped by intensified anthropogenic N input.展开更多
In order to select the strain that can degrade nitrite, the screening plate with nitrite was used as the sole nitrogen source to screen the strain with ability to degrade nitrite. A strain with nitrite degrading capac...In order to select the strain that can degrade nitrite, the screening plate with nitrite was used as the sole nitrogen source to screen the strain with ability to degrade nitrite. A strain with nitrite degrading capacity was isolated from the sludge of a shrimp-farming pond in Hepu City, Guangxi Zhuang Autonomous Region. The isolated strain was identified based on colonial morphology, physiological and biochemical characteristics, and 16S rRNA sequence. Results showed that the strain could grow well on the culture medium containing 2.3 g/L nitrite. According to the morphological characteristics, nitrogen source requirements and evolutionary tree of the 16S rRNA sequence, the isolated strain was identified as Acinetobacter radioresistens, which was named HPAR132 strain. This study laid the foundation for further investigation of nitrite-oxidizing bacterium HPAR132.展开更多
Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Exper...Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Experiments were conducted with the composition of medium components obtained by genetic algorithm, and the experimental data were used to build a BP (back propagation) neural network model. The concentrations of six medium components were used as input vectors, and the nitrite oxidization rate was used as output vector of the model. The BP neural network model was used as the objective function of genetic algorithm to find the optimum medium composition for the maximum nitrite oxidization rate. The maximum nitrite oxidization rate was 0.952 g 2 NO-2-N·(g MLSS)-1·d-1 , obtained at the genetic algorithm optimized concentration of medium components (g·L-1 ): NaCl 0.58, MgSO 4 ·7H 2 O 0.14, FeSO 4 ·7H 2 O 0.141, KH 2 PO 4 0.8485, NaNO 2 2.52, and NaHCO 3 3.613. Validation experiments suggest that the experimental results are consistent with the best result predicted by the model. A scale-up experiment shows that the nitrite degraded completely after 34 h when cultured in the optimum medium, which is 10 h less than that cultured in the initial medium.展开更多
Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to...Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to label the active bacteria using the soil samples from a fully factorial Simulated Climate Change(SCC)field experiment where soils were exposed to ambient CO_(2) and temperature,elevated temperature,elevated CO_(2),and both elevated CO_(2) and temperature.Around 28.9% of active OTUs belonged to ammonia-oxidizing bacteria(AOB)and nitrite-oxidizing bacteria(NOB).Nitrosospira taxa was dominant in all soils and 80.4% of carbon-fixing bacteria under elevated temperature were classified as Nitrosomonas nitrosa.While no labeled NOBs were detected when temperature or CO_(2) were elevated independently,diverse NOBs were detected in the ambient conditions.We found that elevated CO_(2) and temperature had contrasting effects on microbial community composition,while relatively small changes were observed when CO_(2) and temperature were elevated simultaneously.Summarily these results suggest that carbon-fixing bacteria can respond positively to elevated CO_(2) concentrations,but when it’s accompanied with increase in the temperature this positive response could be weakened.Multiple abiotic factors thus need to be considered when predicting how microbial communities will respond to multiple climatic factors.展开更多
Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine t...Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine the distribution condition of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in surface sediment in eight sites.The results showed that the amount of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in eight sites were 104-106 CFU/g,105-107 MPN/g,105-108 MPN/g and 105-109 MPN/g,respectively.The sampling site with the largest amount of denitrifier was Daposhang,and the other sampling sites had no significant difference;the sampling site of Huyudong bridge had the largest amount of ammonium-oxidizing bacteria;the amount of nitrite-oxidizing bacteria in Xinzhuang was higher than that of other sampling sites;the sampling site of Daposhang had the larger amount of denitrifier.展开更多
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51108367）, Specialized Research Fund for the Doctoral Program of Higher Education （No. 20116120120009）, Natural Science Foundation of Shaanxi Province （No. 2014JQ7243） and innovative research team of Xi＇an University of Architecture and Technology.
文摘Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for completely autotrophic nitrogen removal over nitrite （CANON）. Fed with synthetic wastewater rich in ammo- nia, the SBR removed 82.54-5.4% ofinfluent nitrogen and a maximum nitrogen-removal rate of 0.52kgN.m 3.d-l was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria （AerAOB） Nitrosomonas and anaerobic ammonium-oxidizing bacteria （AnAOB） dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen （DO）, NH＋, NO＋ and NO3 microelectrodes. In the outer layer of sludge aggregates （0-700 μm）, nitrite-oxidizing bacteria （NOB） showed high activity with 4.1 gmol-cm3＋ h-1 of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg. L 1. Maximum AerAOB activity was detected in the middle layer （depths around 1700 μm） where DO concentration was 1.1 μg. L-1. In the inner layer （2200-3500μm）, where DO concentration was below 0.9 mg. L-1, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.
基金supported by the National Research University Project,Office of Higher Education Commission(No.WCU-014-FW-57)
文摘Nitrite accumulation in shrimp ponds can pose serious adverse effects to shrimp production and the environment.This study aims to develop an effective process for the enrichment of ready-to-use nitrite-oxidizing bacteria（NOB）inocula that would be appropriate for nitrite removal in brackish shrimp ponds.To achieve this objective,the effects of nitrite concentrations on NOB communities and nitrite oxidation kinetics in a brackish environment were investigated.Moving-bed biofilm sequencing batch reactors and continuous moving-bed biofilm reactors were used for the enrichment of NOB at various nitrite concentrations,using sediment from brackish shrimp ponds as seed inoculum.The results from NOB population analysis with quantitative polymerase chain reaction（q PCR）show that only Nitrospira were detected in the sediment from the shrimp ponds.After the enrichment,both Nitrospira and Nitrobacter coexisted in the reactors controlling effluent nitrite at 0.1 and 0.5 mg-NO2^--N/L.On the other hand,in the reactors controlling effluent nitrite at 3,20,and 100 mg-NO2^--N/L,Nitrobacter outcompeted Nitrospira in many orders of magnitude.The half saturation coefficients（Ks）for nitrite oxidation of the enrichments at low nitrite concentrations（0.1 and 0.5 mg-NO2^--N/L）were in the range of 0.71–0.98 mg-NO2^--N/L.In contrast,the Ksvalues of NOB enriched at high nitrite concentrations（3,20,and 100 mg-NO2^--N/L）were much higher（8.36–12.20 mg-NO2^--N/L）.The results suggest that the selection of nitrite concentrations for the enrichment of NOB inocula can significantly influence NOB populations and kinetics,which could affect the effectiveness of their applications in brackish shrimp ponds.
基金supported by the Ratchadaphiseksomphot Endowment Fund
文摘The effects of chitosan characteristics including the degree of deacetylation, molecular weight, particle size, pH pretreatment and immobilization time on the immobilization of nitrite-oxidizing bacteria （NOB） on biopolymeric chitosan were investigated. Nitrite removal efficiency of immobilized NOB depended on the degree of deacetylation, particle size, pH pretreatment on the surface of chitosan and immobilization time. Scanning electron microscope characterization illustrated that the number of NOB cells attached to the surface of chitosan increased with an increment of immobilization time. The optimal condition for NOB immobilization on chitosan was achieved during a 24-hr immobilization period using chitosan with the degree of deacetylation larger than 80% and various particle size ranges between 1-5 mm at pH 6.5. In general, the NOB immobilized on chitosan flakes has a high potential to remove excess nitrite from wastewater and aquaculture systems.
基金funded by the National Key Research and Development Project of China (No. 2016YFD0800100-04)。
文摘Nitrate (NO-3) and nitrite (NO2-) leaching threatens groundwater quality.Soil C:N ratio,i.e.,the ratio of soil organic carbon to total nitrogen,affects mineralization,nitrification,and denitrification;however,its mechanism for driving soil NO-3and NO-2accumulation and leaching remains unclear.Here,a field investigation in a fluvo-aquic soil and a soil column experiment were performed to explore the relationships between soil C:N ratio and soil NO-3and NO-2leaching in three soil layers (0–20,20–40,and 40–60 cm) under heavy rainfall (rainfall rate>25 mm d-1).The field investigation results showed that both soil NO-3-N and NO-2-N contents decreased exponentially (P<0.001) with increasing soil C:N ratio in each soil layer.Furthermore,negative exponential relationships (P<0.001) were found between soil C:N ratio and both NO-3-N and NO-2-N concentrations in soil solution in each soil layer under heavy rainfall.The soil column divided into three layers was leached with simulated heavy rainfall;the results confirmed negative exponential relationships (P<0.05) between soil C:N ratio and both NO-3-N and NO-2-N concentrations in the leachate from each soil layer.A total of 18 soil samples obtained from three depths at six field sites during the rainy season were used to elucidate the microbial mechanisms induced by soil C:N ratio using high-throughput sequencing and real-time polymerase chain reaction.High abundances of ammonifying bacteria (Flavobacterium,Bacillu,and Pseudomonas),ammonia-oxidizing bacteria (Nitrosospira),and nirS/K gene were observed when soil C:N was low,concomitant with low abundances of NO-2-oxidizing bacteria (Nitrospira) and narG gene.Partial least squares path modeling showed that the high NO-3and NO-2levels at low soil C:N ratio might be attributed to the inhibition of NO-3reduction (i.e.,low narG gene) and NO-2oxidation (i.e.,low Nitrospira) and thus the accumulation of soil NO-3and NO-2,respectively.Therefore,the leaching of NO-2and NO-3in low C:N soils requires more attention during the rai
基金the National Natural Science Foundation of China(Nos.41530857 and 41471208)the National Key Basic Research Program of China(No.2015CB150501)+2 种基金the Department of Agriculture,Environment,and Rural Affairs(DAERA)in Northern Ireland,UK(No.700141499)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB15040000)the Startup Foundation for Introducing Talent of the Nanjing University of Information Science and Technology(NUIST),China(No.S8113117001).
文摘Long-term nitrogen(N)fertilization imposes strong selection on nitrifying communities in agricultural soil,but how a progressively changing niche affects potentially active nitrifiers in the field remains poorly understood.Using a 44-year grassland fertilization experiment,we investigated community shifts of active nitrifiers by DNA-based stable isotope probing(SIP)of field soils that received no fertilization(CK),high levels of organic cattle manure(HC),and chemical N fertilization(CF).Incubation of DNA-SIP microcosms showed significant nitrification activities in CF and HC soils,whereas no activity occurred in CK soils.The 44 years of inorganic N fertilization selected only 13C-ammonia-oxidizing bacteria(AOB),whereas cattle slurry applications created a niche in which both ammonia-oxidizing archaea(AOA)and AOB could be actively13C-labeled.Phylogenetic analysis indicated that Nitrosospira sp.62-like AOB dominated inorganically fertilized CF soils,while Nitrosospira sp.41-like AOB were abundant in organically fertilized HC soils.The 13C-AOA in HC soils were affiliated with the 29i4 lineage.The 13C-nitrite-oxidizing bacteria(NOB)were dominated by both Nitrospira-and Nitrobacter-like communities in CF soils,and the latter was overwhelmingly abundant in HC soils.The 13C-labeled nitrifying communities in SIP microcosms of CF and HC soils were largely similar to those predominant under field conditions.These results provide direct evidence for a strong selection of distinctly active nitrifiers after 44 years of different fertilization regimes in the field.Our findings imply that niche differentiation of nitrifying communities could be assessed as a net result of microbial adaption over 44 years to inorganic and organic N fertilization in the field,where distinct nitrifiers have been shaped by intensified anthropogenic N input.
文摘In order to select the strain that can degrade nitrite, the screening plate with nitrite was used as the sole nitrogen source to screen the strain with ability to degrade nitrite. A strain with nitrite degrading capacity was isolated from the sludge of a shrimp-farming pond in Hepu City, Guangxi Zhuang Autonomous Region. The isolated strain was identified based on colonial morphology, physiological and biochemical characteristics, and 16S rRNA sequence. Results showed that the strain could grow well on the culture medium containing 2.3 g/L nitrite. According to the morphological characteristics, nitrogen source requirements and evolutionary tree of the 16S rRNA sequence, the isolated strain was identified as Acinetobacter radioresistens, which was named HPAR132 strain. This study laid the foundation for further investigation of nitrite-oxidizing bacterium HPAR132.
基金Supported by the National Natural Science Foundation of China (21076090)
文摘Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Experiments were conducted with the composition of medium components obtained by genetic algorithm, and the experimental data were used to build a BP (back propagation) neural network model. The concentrations of six medium components were used as input vectors, and the nitrite oxidization rate was used as output vector of the model. The BP neural network model was used as the objective function of genetic algorithm to find the optimum medium composition for the maximum nitrite oxidization rate. The maximum nitrite oxidization rate was 0.952 g 2 NO-2-N·(g MLSS)-1·d-1 , obtained at the genetic algorithm optimized concentration of medium components (g·L-1 ): NaCl 0.58, MgSO 4 ·7H 2 O 0.14, FeSO 4 ·7H 2 O 0.141, KH 2 PO 4 0.8485, NaNO 2 2.52, and NaHCO 3 3.613. Validation experiments suggest that the experimental results are consistent with the best result predicted by the model. A scale-up experiment shows that the nitrite degraded completely after 34 h when cultured in the optimum medium, which is 10 h less than that cultured in the initial medium.
基金supported by the National Key Research and Development Program of China(2017YFD0200805)the Special Fund for Agriculture Profession(20150312205)the Innovative Research Team Development Plan of the Ministry of Education of China(IRT_17R56).
文摘Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to label the active bacteria using the soil samples from a fully factorial Simulated Climate Change(SCC)field experiment where soils were exposed to ambient CO_(2) and temperature,elevated temperature,elevated CO_(2),and both elevated CO_(2) and temperature.Around 28.9% of active OTUs belonged to ammonia-oxidizing bacteria(AOB)and nitrite-oxidizing bacteria(NOB).Nitrosospira taxa was dominant in all soils and 80.4% of carbon-fixing bacteria under elevated temperature were classified as Nitrosomonas nitrosa.While no labeled NOBs were detected when temperature or CO_(2) were elevated independently,diverse NOBs were detected in the ambient conditions.We found that elevated CO_(2) and temperature had contrasting effects on microbial community composition,while relatively small changes were observed when CO_(2) and temperature were elevated simultaneously.Summarily these results suggest that carbon-fixing bacteria can respond positively to elevated CO_(2) concentrations,but when it’s accompanied with increase in the temperature this positive response could be weakened.Multiple abiotic factors thus need to be considered when predicting how microbial communities will respond to multiple climatic factors.
基金Supported by Science and Technology Found Project of Guizhou Province(QKH J[2008]2239)~~
文摘Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine the distribution condition of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in surface sediment in eight sites.The results showed that the amount of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in eight sites were 104-106 CFU/g,105-107 MPN/g,105-108 MPN/g and 105-109 MPN/g,respectively.The sampling site with the largest amount of denitrifier was Daposhang,and the other sampling sites had no significant difference;the sampling site of Huyudong bridge had the largest amount of ammonium-oxidizing bacteria;the amount of nitrite-oxidizing bacteria in Xinzhuang was higher than that of other sampling sites;the sampling site of Daposhang had the larger amount of denitrifier.
