关键词: 生物固氮；固氮基因簇；结构与进化

Abstract:

The genes associated with nitrogen fixation are often grouped in one or several contiguous units of the diazotrophic genome, which are the genetic basis of biological nitrogen fixation. Among them there are nitrogenase structural genes nifHDK, and many additional genes involved in electron transport and FeMocofactor biosynthesis and assembly. This paper conducted simple comparative analysis on the relationship between organization and evolution of nitrogenfixation gene clusters. Through comparing the nitrogenfixation gene clusters in all sequenced diazotrophs, we found that there were at least 6 conservative genes: nifH, nifD, nifK, nifE, nifN, and nifB, and all of them were essential for nitrogen fixation in characterized systems. Although there are some differences in their structures and organizing patterns by different diazotrophs. These nitrogenfixation gene clusters are structurally, mechanistically, and phylogenetically closely related. Meanwhile, the paper also prospected directions for studying nitrogenfixation genes. It aimed to provide theoretical basis for further studying the mechanism of biological nitrogen fixation and understanding the evolution of microbial nitrogen fixation.

Key words: biological nitrogen fixation, nitrogenfixation gene clusters, structure and evolution