Four gene clusters associated with denitrification were identified in the genome of A1501 strain, nar, nir, nor and nos, including 40 genes totally, which encode proteins for sub-stance transportation, gene regulation and reductases. The three gene clusters, nir, nor and nos are adjacent on chromosome and are far from nar gene cluster. Compared with other denitrifying bacteria, the 40 denitrification genes in A1501 strain compose a complete denitrification catalysis system. In A1501 strain, this system has the following characteristics: (i) only one copy of narK gene is found in nar gene cluster; (ii) a narM gene is present between narK and narG; (iii) two genes, dnarE and orfl are identified at downstream of narX and narL genes, of which dnrE per-haps is a transcriptional factor belonging to FNR family; (iv) there are 16 nir genes in A1501, the most in the known denitrifying bacteria; (v) it is for the first time that norR gene has been found in A1501 and also in Pseudomonas; (vi) nos gene cluster is relatively conservative, with a com-pletely identical composition and arrangement of genome to the reference bacteria strain.
YAN Yongliang1,2, YANG Jian2, CHEN Lihong2, YANG Fan2, DONG Jie2, XUE Ying2, XU Xingye2, ZHU Yafang2, YAO Zhijian3, LIN Min4, WANG Yiping5 & JIN Qi1,2 1. College of Biological Sciences, China Agricultural University, Beijing 100094, China
