Atmospheric nitrogen deposition and precipitation as an important phenomenon of global climate change have a great impact on grassland ecosystems. However, little is known about how the soil ammonia-oxidizing microorg...Atmospheric nitrogen deposition and precipitation as an important phenomenon of global climate change have a great impact on grassland ecosystems. However, little is known about how the soil ammonia-oxidizing microorganisms respond to the both changes. Ammonia oxidization is a crucial step in the soil nitrification and greatly inlfuenced by soil nitrogen availability. We used PCR and DGGE （denaturing gradient gel electrophoresis） approaches to investigate the responses of AOB （ammonia-oxidizing bacteria） 16S rRNA and AOA （ammonia-oxidizing archaea）amoA genes to nitrogen and water input inStipa baicalensis steppe, Inner Mongolia, northern China. After two years of nitrogen and water addition treatment, it was found that PNA （potential nitriifcation activity） was greatly enhanced by lower N fertilization treatment under water addition and higher N fertilization under no-water addition, while it decreased markedly in higher N fertilization under water addition. The community structure of AOB responded more sensitively to N fertilization and water input than AOA, resulting in the significantly decreased diversity in the AOB community along with a higher N fertilizer rate, but an obvious increase in the AOA community, demonstrating the active growth of AOA in higher N fertilization soils. Phylogenetic analysis showed that AOB communities were dominated byNitrosospira clusters3, 4 andNitrososmonas clusters 6 under water addition andNitrosospira culsters 1, 3 and 4 and under no-water addition, while AOA communities were grouped intoCrenarchaeote clusters 1, 2 and 5 under no-water addition and Crenarchaeote clusters 1, 2 and water lineage under water addition. The differences between the two water addition regimes strongly suggest that water input acts as an important role in shifting AOA and AOB communities. Moreover, in contrast to the AOA, the diversity of AOB was negatively correlated with total N, NH4^＋, NO3^- and pH under water addition, implying a signiifcant N fertilization and water effect on shaping AOA and AOB communities. In conclusion, our studies suggested that N fertilization and water addition and their composite effects had signiifcantly changed AOB and AOA communities, meanwhile, AOB and AOA communities could develop a desirable complementary mechanism in response to external changes.展开更多
Chlorpyrifos is a widely used insecticide in recent years,and it will produce adverse effects on soil when applied on crops or mixed with soil.In this study,nested polymerase chain reaction（PCR） and denaturing gradi...Chlorpyrifos is a widely used insecticide in recent years,and it will produce adverse effects on soil when applied on crops or mixed with soil.In this study,nested polymerase chain reaction（PCR） and denaturing gradient gel electrophoresis（DGGE） were combined to explore the bacterial and fungal community successions in soil treated with 5 and 20 mg/kg of chlorpyrifos.Furthermore,isolates capable of efficiently decomposing chlorpyrifos were molecular-typed using enterobacterial repetitive intergenic consensus-PCR（ERIC-PCR）.Under the experimental conditions,degradation of chlorpyrifos in soil was interpreted with the first-order kinetics,and the half-lives of chlorpyrifos at 5 and 20 mg/kg doses were calculated to be 8.25 and 8.29 d,respectively.DGGE fingerprint and principal component analysis（PCA） indicated that the composition of the fungal community was obviously changed with the chlorpyrifos treatment,and that samples of chlorpyrifos treatment were significantly separated from those of the control from the beginning to the end.While for the bacterial community,chlorpyrifos-treated soil samples were apparently different in the first 30 d and recovered to a similar level of the control up until 60 d,and the distance in the PCA between the chlorpyrifos-treated samples and the control was getting shorter through time and was finally clustered into one group.Together,our results demonstrated that the application of chlorpyrifos could affect the fungal community structure in a quick and lasting way,while only affecting the bacterial community in a temporary way.Finally,nine typical ERIC types of chlorpyrifos-degrading isolates were screened.展开更多
基金National Natural Science Foundation of China(31170435,31000242)
文摘Atmospheric nitrogen deposition and precipitation as an important phenomenon of global climate change have a great impact on grassland ecosystems. However, little is known about how the soil ammonia-oxidizing microorganisms respond to the both changes. Ammonia oxidization is a crucial step in the soil nitrification and greatly inlfuenced by soil nitrogen availability. We used PCR and DGGE （denaturing gradient gel electrophoresis） approaches to investigate the responses of AOB （ammonia-oxidizing bacteria） 16S rRNA and AOA （ammonia-oxidizing archaea）amoA genes to nitrogen and water input inStipa baicalensis steppe, Inner Mongolia, northern China. After two years of nitrogen and water addition treatment, it was found that PNA （potential nitriifcation activity） was greatly enhanced by lower N fertilization treatment under water addition and higher N fertilization under no-water addition, while it decreased markedly in higher N fertilization under water addition. The community structure of AOB responded more sensitively to N fertilization and water input than AOA, resulting in the significantly decreased diversity in the AOB community along with a higher N fertilizer rate, but an obvious increase in the AOA community, demonstrating the active growth of AOA in higher N fertilization soils. Phylogenetic analysis showed that AOB communities were dominated byNitrosospira clusters3, 4 andNitrososmonas clusters 6 under water addition andNitrosospira culsters 1, 3 and 4 and under no-water addition, while AOA communities were grouped intoCrenarchaeote clusters 1, 2 and 5 under no-water addition and Crenarchaeote clusters 1, 2 and water lineage under water addition. The differences between the two water addition regimes strongly suggest that water input acts as an important role in shifting AOA and AOB communities. Moreover, in contrast to the AOA, the diversity of AOB was negatively correlated with total N, NH4^＋, NO3^- and pH under water addition, implying a signiifcant N fertilization and water effect on shaping AOA and AOB communities. In conclusion, our studies suggested that N fertilization and water addition and their composite effects had signiifcantly changed AOB and AOA communities, meanwhile, AOB and AOA communities could develop a desirable complementary mechanism in response to external changes.
基金supported by the Zhejiang Provincial Key Technology Innovation Team(No.2010R50028)the Hangzhou Science and Technology Development Program(No.20110232B11),China
文摘Chlorpyrifos is a widely used insecticide in recent years,and it will produce adverse effects on soil when applied on crops or mixed with soil.In this study,nested polymerase chain reaction（PCR） and denaturing gradient gel electrophoresis（DGGE） were combined to explore the bacterial and fungal community successions in soil treated with 5 and 20 mg/kg of chlorpyrifos.Furthermore,isolates capable of efficiently decomposing chlorpyrifos were molecular-typed using enterobacterial repetitive intergenic consensus-PCR（ERIC-PCR）.Under the experimental conditions,degradation of chlorpyrifos in soil was interpreted with the first-order kinetics,and the half-lives of chlorpyrifos at 5 and 20 mg/kg doses were calculated to be 8.25 and 8.29 d,respectively.DGGE fingerprint and principal component analysis（PCA） indicated that the composition of the fungal community was obviously changed with the chlorpyrifos treatment,and that samples of chlorpyrifos treatment were significantly separated from those of the control from the beginning to the end.While for the bacterial community,chlorpyrifos-treated soil samples were apparently different in the first 30 d and recovered to a similar level of the control up until 60 d,and the distance in the PCA between the chlorpyrifos-treated samples and the control was getting shorter through time and was finally clustered into one group.Together,our results demonstrated that the application of chlorpyrifos could affect the fungal community structure in a quick and lasting way,while only affecting the bacterial community in a temporary way.Finally,nine typical ERIC types of chlorpyrifos-degrading isolates were screened.
