Potrich D P, Passaglia L M, Schrank I S
Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
Braz J Med Biol Res. 2001 Sep;34(9):1105-13. doi: 10.1590/s0100-879x2001000900002.
Azospirillum amazonense revealed genomic organization patterns of the nitrogen fixation genes similar to those of the distantly related species A. brasilense. Our work suggests that A. brasilense nifHDK, nifENX, fixABC operons and nifA and glnB genes may be structurally homologous to the counterpart genes of A. amazonense. This is the first analysis revealing homology between A. brasilense nif genes and the A. amazonense genome. Sequence analysis of PCR amplification products revealed similarities between the amino acid sequences of the highly conserved nifD and glnB genes of A. amazonense and related genes of A. brasilense and other bacteria. However, the A. amazonense non-coding regions (the upstream activator sequence region and the region between the nifH and nifD genes) differed from related regions of A. brasilense even in nitrogenase structural genes which are highly conserved among diazotrophic bacteria. The feasibility of the 16S ribosomal RNA gene-based PCR system for specific detection of A. amazonense was shown. Our results indicate that the PCR primers for 16S rDNA defined in this article are highly specific to A. amazonense and can distinguish this species from A. brasilense.
亚马逊固氮螺菌显示出与远缘物种巴西固氮螺菌相似的固氮基因基因组组织模式。我们的研究表明，巴西固氮螺菌的nifHDK、nifENX、fixABC操纵子以及nifA和glnB基因可能在结构上与亚马逊固氮螺菌的对应基因同源。这是首次揭示巴西固氮螺菌nif基因与亚马逊固氮螺菌基因组之间同源性的分析。PCR扩增产物的序列分析揭示了亚马逊固氮螺菌高度保守的nifD和glnB基因的氨基酸序列与巴西固氮螺菌及其他细菌的相关基因之间的相似性。然而，即使在固氮酶结构基因方面（这些基因在固氮细菌中高度保守），亚马逊固氮螺菌的非编码区（上游激活序列区以及nifH和nifD基因之间的区域）也与巴西固氮螺菌的相关区域不同。研究显示了基于16S核糖体RNA基因的PCR系统用于特异性检测亚马逊固氮螺菌的可行性。我们的结果表明，本文定义的16S rDNA PCR引物对亚马逊固氮螺菌具有高度特异性，能够将该物种与巴西固氮螺菌区分开来。
