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
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
So far studies have focused on bacteria isolation aimed at establishing causes of fish diseases and medication methods.Now,more and more attention has been given to the composition of the microflora,its variations in ...So far studies have focused on bacteria isolation aimed at establishing causes of fish diseases and medication methods.Now,more and more attention has been given to the composition of the microflora,its variations in time,and effect on whiteleg shrimp(Litopenaeus vannamei).This is why the problem of bacterial flora in water ought to be studied.The major role of ammonifying bacteria is to break down nitrogenous organic matter to ammoniac nitrogen.The research of ammonifers in the pond water of Litopenaeus vannamei is increasing with the demand for environment friendly aquaculture.Four bacterial strains(No.zjs01,zjs02,zjs03 and zjs04),isolated from the pond water of Litopenaeus vannamei in Jinshan district of Shanghai,were cultured in ammonifying bacteria rich medium and identified by two methods.One is the sequence analysis of 16S rDNA,the other is bacteria identification system.First,sequence analysis of the 16S rDNA was done.Genomic DNA of four strains was isolated respectively,then their full length of the 16S rDNA were amplified by PCR respectively,using universal primers to the 16S rDNA.After purification by gel extraction,the PCR products were cloned and subsequently sequenced by Shanghai Invitrogen Biotechnology Company(SIBC).The phylogenetic trees were constructed,based on the result of online alignment.At the same time,the four sequences of 16S rDNA were submitted to NCBI(http://www.ncbi.nlm.nih.gov) in order to obtain accession number of strains of zjs01,zjs02,zjs03 and zjs04.Then the API 2000 Bacteria Identification System(Biomerieux Company) was applied in assessment the identification result of zjs01,zjs02,zjs03 and zjs04 by molecular method.Finally the 4 strains were identified as,zjs01: Brevundimonas diminuta,zjs02 and zjs03: Alcaligenes faecalis,zjs04: Enterobacter aerogenes.And the accession number of the strains(zjs01,zjs02,zjs03 and zjs04) is DQ857897,DQ857898, DQ857895,DQ857896 respectively.The method of detecting bacterial 16S rDNA using PCR technique is specific,sensitive,rapid and accurate i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
文摘So far studies have focused on bacteria isolation aimed at establishing causes of fish diseases and medication methods.Now,more and more attention has been given to the composition of the microflora,its variations in time,and effect on whiteleg shrimp(Litopenaeus vannamei).This is why the problem of bacterial flora in water ought to be studied.The major role of ammonifying bacteria is to break down nitrogenous organic matter to ammoniac nitrogen.The research of ammonifers in the pond water of Litopenaeus vannamei is increasing with the demand for environment friendly aquaculture.Four bacterial strains(No.zjs01,zjs02,zjs03 and zjs04),isolated from the pond water of Litopenaeus vannamei in Jinshan district of Shanghai,were cultured in ammonifying bacteria rich medium and identified by two methods.One is the sequence analysis of 16S rDNA,the other is bacteria identification system.First,sequence analysis of the 16S rDNA was done.Genomic DNA of four strains was isolated respectively,then their full length of the 16S rDNA were amplified by PCR respectively,using universal primers to the 16S rDNA.After purification by gel extraction,the PCR products were cloned and subsequently sequenced by Shanghai Invitrogen Biotechnology Company(SIBC).The phylogenetic trees were constructed,based on the result of online alignment.At the same time,the four sequences of 16S rDNA were submitted to NCBI(http://www.ncbi.nlm.nih.gov) in order to obtain accession number of strains of zjs01,zjs02,zjs03 and zjs04.Then the API 2000 Bacteria Identification System(Biomerieux Company) was applied in assessment the identification result of zjs01,zjs02,zjs03 and zjs04 by molecular method.Finally the 4 strains were identified as,zjs01: Brevundimonas diminuta,zjs02 and zjs03: Alcaligenes faecalis,zjs04: Enterobacter aerogenes.And the accession number of the strains(zjs01,zjs02,zjs03 and zjs04) is DQ857897,DQ857898, DQ857895,DQ857896 respectively.The method of detecting bacterial 16S rDNA using PCR technique is specific,sensitive,rapid and accurate i
