In this study,the bacteria from the mud in tidal-flat Sinonovacula constricta aquaculture area were isolated each month from March to December,2002,and the temporal and spatial distribution of heterotrophic bacteria,a...In this study,the bacteria from the mud in tidal-flat Sinonovacula constricta aquaculture area were isolated each month from March to December,2002,and the temporal and spatial distribution of heterotrophic bacteria,ammonifying bacteria,denitrifying bacteria,and sulphate reducing bacteria were analyzed.The results showed that all the 515 isolated bacteria mainly belonged to 1 family and 13 genera.The bacterial flora in different layers of the mud was almost consistent,while the composition was different.The predominant genera were Clostridium,Bacillus,Corynebacterium,Photobacterium,and some Enterobacteriaceae.The number of heterotrophic bacteria in the surface layer and the bottom fluctuated in 7.6×103 cfu·g-1～2.0×105 and 1.6×103～1.0×105 cfu·g-1,ammonifying bacteria fluctuated in 1.5×106～9.0×107 and 9.0×105～1.0×107 cfu·g-1,denitrifying bacteria fluctuated in 9.0×103～4.0×106 and 5.0×102～1.9×106 cfu·g-1,and sulphate reducing bacteria fluctuated in 5.0×104～5.0×106 and 1.9×104～2.0×106 cfu·g-1,respectively.The detection rates of ammonifying bacteria,denitrifying bacteria and sulphate reducing bacteria in the mud were all 100%,and these bacteria increased significantly in the second half of the year,indicating that the environment of the Sinonovacula constricta aquaculture area was deteriorated due to the accumulation of NH3,nitrite and H2S,and it is important to regulate the breed capacity and redistribute the breeding environment.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
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 rainy season.展开更多
文摘In this study,the bacteria from the mud in tidal-flat Sinonovacula constricta aquaculture area were isolated each month from March to December,2002,and the temporal and spatial distribution of heterotrophic bacteria,ammonifying bacteria,denitrifying bacteria,and sulphate reducing bacteria were analyzed.The results showed that all the 515 isolated bacteria mainly belonged to 1 family and 13 genera.The bacterial flora in different layers of the mud was almost consistent,while the composition was different.The predominant genera were Clostridium,Bacillus,Corynebacterium,Photobacterium,and some Enterobacteriaceae.The number of heterotrophic bacteria in the surface layer and the bottom fluctuated in 7.6×103 cfu·g-1～2.0×105 and 1.6×103～1.0×105 cfu·g-1,ammonifying bacteria fluctuated in 1.5×106～9.0×107 and 9.0×105～1.0×107 cfu·g-1,denitrifying bacteria fluctuated in 9.0×103～4.0×106 and 5.0×102～1.9×106 cfu·g-1,and sulphate reducing bacteria fluctuated in 5.0×104～5.0×106 and 1.9×104～2.0×106 cfu·g-1,respectively.The detection rates of ammonifying bacteria,denitrifying bacteria and sulphate reducing bacteria in the mud were all 100%,and these bacteria increased significantly in the second half of the year,indicating that the environment of the Sinonovacula constricta aquaculture area was deteriorated due to the accumulation of NH3,nitrite and H2S,and it is important to regulate the breed capacity and redistribute the breeding environment.
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.
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 rainy season.
