1.南京信息工程大学环境科学与工程学院/江苏省大气环境监测与污染控制高技术研究重点实验室/江苏省大气环境与装备技术协同创新中心，南京 210044;2.南京工业大学生物与制药工程学院/国家生化工程技术研究中心，南京 211816
1.School of Environmental Science and Engineering, Nanjing University of Information Science and Technology / Key Laboratory of High Technology Research on Atmospheric Environment Monitoring and Pollution Control in Jiangsu Province / Jiangsu Atmospheric Environment and Equipment Technology Collaborative Innovation Center, Nanjing 210044, China;2.School of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University / National Engineering Research Center for Biotechnology, Nanjing 211816, China
The National Natural Science Foundation of China
Nitrous oxide (N2O), an important greenhouse gas, has a global warming potential of 265 times higher than that of an equivalent concentration of carbon dioxide. The N2O has a long atmospheric lifetime and does deplete the ozone layer in the stratosphere. Agricultural soil is an important source of N2O, which has a characteristic of diverse generation paths, multiple impact factors, and complicated regulation processes. Mitigation of N2O emissions from agricultural soils has long been the hotspot of research in this field. N2O-reducing bacteria harboring N2O reductase can reduce N2O to dinitrogen (N2), which is the only known sink of N2O consumption as a primary substrate in the biosphere. The direct use of microorganisms to decrease N2O emissions from agricultural soils is an emerging technology. We elaborated on the biological sources and sinks of N2O emissions from agricultural soils in detail, paying special emphasis on the screening and application strategies of microorganisms that can mitigate N2O emissions. There are three strategies for the direct use of microorganisms to decrease N2O emissions from agricultural soils: (1) application of the prepared microbial inoculum directly to the agricultural soil; (2) combination of the prepared microbial inoculum with fertilizers or other carriers before being applied to the soil; (3) construction of the microbial community with N2O mitigation effect, and then direct application to the soil or in combination with a carrier before being applied to the soil. We summarized two ecological mechanisms of microbial-mediated mitigation of N2O emissions from agricultural soils. One mechanism involved employing N2O-reducing bacteria containing nosZ gene to directly convert N2O to N2 in order to mitigate N2O emissions from agricultural soils. The other mechanism utilizes plant growth-promoting rhizobacteria to alter the community composition, abundance and activity of the N2O-reducing bacteria and indirectly mitigate N2O emissions from agricultural soils. We also discussed the environmental factors that affect the reduction of N2O to N2 by directly using microorganisms and the potential challenges. The biological process of reducing N2O to N2 is affected by many environmental factors, including the availability of NO3? and carbon sources, oxygen concentration, moisture content, temperature, pH and copper concentration. Among them, Cu availability and pH are some of the most important factors that determine the activity of N2OR. Several issues need to be addressed in future studies. For example, there are only a limited number of strains that have been screened with N2O mitigating effects. It remains unknown whether the inoculum colonizes roots or survive in the environment after the inoculation. The microbial ecological mechanisms are poorly understood; such as, how the inoculum achieve their beneficial effects in environments. Moreover, we lack effective technical means to regulate the inoculum to fully exploit their beneficial effects. Further, the methods to evaluate N2O mitigating effects also need to be improved. Finally, prospects on the application of microbial-mediated mitigation of N2O emissions from agricultural soils were suggested. The review provides an important technical reference for achieving the agricultural carbon neutrality strategic goal in China.
Shen Weishou, Xiong Ruonan, Zhang Huanhuan, Yang Siqi, Gao Nan. Research Progress on Microbial-Mediated Mitigation of Nitrous Oxide Emissions from Agricultural Soils[J]. Acta Pedologica Sinica,,[In Press]