Nitrous oxide (N2O) is a small but potent greenhouse gas and tends to accumulate as an intermediate in the process of bacterial denitrification.In order to achieve the complete reduction of nitrogen oxide (NOx)in bacteria denitrification,the nosZencoding the nitrous oxide reductase (N2OR)was cloned from Alcaligenes denitrificans strain TB (GenBank JQ044686).The recombinant plasmid that contains nosZ gene was built and expression of nosZ gene in Escherichia coli was carried out.The results show that nosZ gene consists of 1917 nucleotides achieves heterologous expression successfully after induction by IPTG under the optimal conditions that pre-induction inoculum OD600,final IPTG concentration,inducing time and inducing temperature are 0.67,0.5mM,6 h and 28 ℃,respectively.Determination result of gas chromatography identifies that the N2O degradation efficiency of recombinant E.coliis enhance by at least 1.92 times compared to that of original strain TB when treated with N2O as substrate,and the result that the N2OR activity in recombinant strain is 2.09 times higher than that in wild strain TB also validates this,implying that the recombinant E.coli BL21 (DE3)-pET28b-nosZ is a potential candidate to control N2O accumulation.Importance: This study reports the construction of the nosZgene expression system,resulting in a recombinant E.colistraincapable of efficiently expressing nitrous oxide reductase (N2OR).The predicted N2OR structure is similar to that of Pseudomonas stutzeri.The N2OR specific enzyme activity of recombinant was 1.056 U/mg,56.08% of the N2O reduction efficiency of recombinant was 1.92 times higher than that of wild bacteria.The higher enzyme activity and reducing capacity of recombinant E.coli imply applications in reducing N2O release and alleviating greenhouse effect,and also open an avenue for further research on the relationship between N2OR enzyme activity and its structure.