Climate change is altering the timing and magnitude of biogeochemical fluxes in many high- elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale res...Climate change is altering the timing and magnitude of biogeochemical fluxes in many high- elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats （glacial outwash, talus, and meadow）. We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing tempera- tures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.展开更多
The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determi...The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determined.Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles,which showed that each population had a consistent profile although the abundance of individual members varied.In the aerobic tanks,the ammonia-oxidizing bacterial(AOB)population was more than 350 times more abundant than the ammonia-oxidizing archaeal(AOA)population,however in the digesters,the AOA population was more than 10 times more abundant.Measuring the activity of the amo A gene expression of the two populations using RT-PCR also showed that the AOA amo A gene was more active in the digesters than in the activated sludge tanks.Using batch reactors and dd PCR,amo A activity could be measured and it was found that when the AOB amo A activity was inhibited in the anoxic reactors,the expression of the AOA amo A gene increased fourfold.This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.展开更多
文摘Climate change is altering the timing and magnitude of biogeochemical fluxes in many high- elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats （glacial outwash, talus, and meadow）. We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing tempera- tures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant (RGPIN/227565-2013) to K.A.G
文摘The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determined.Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles,which showed that each population had a consistent profile although the abundance of individual members varied.In the aerobic tanks,the ammonia-oxidizing bacterial(AOB)population was more than 350 times more abundant than the ammonia-oxidizing archaeal(AOA)population,however in the digesters,the AOA population was more than 10 times more abundant.Measuring the activity of the amo A gene expression of the two populations using RT-PCR also showed that the AOA amo A gene was more active in the digesters than in the activated sludge tanks.Using batch reactors and dd PCR,amo A activity could be measured and it was found that when the AOB amo A activity was inhibited in the anoxic reactors,the expression of the AOA amo A gene increased fourfold.This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.
