Garbeva Paolina, Baggs Elizabeth M, Prosser James I
School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
FEMS Microbiol Lett. 2007 Jan;266(1):83-9. doi: 10.1111/j.1574-6968.2006.00517.x. Epub 2006 Nov 13.
Ammonia-oxidizing bacteria are believed to be an important source of the climatically important trace gas nitrous oxide (N(2)O). The genes for nitrite reductase (nirK) and nitric oxide reductase (norB), putatively responsible for nitrous oxide production, have been identified in several ammonia-oxidizing bacteria, but not in Nitrosospira strains that may dominate ammonia-oxidizing communities in soil. In this study, sequences from nirK and norB genes were detected in several cultured Nitrosospira species and the diversity and phylogeny of these genes were compared with those in other ammoniaoxidizing bacteria and in classical denitrifiers. The nirK and norB gene sequences obtained from Nitrosospira spp. were diverse and appeared to be less conserved than 16S rRNA genes and functional ammonia monooxygenase (amoA) genes. The nirK and norB genes from some Nitrosospira spp. were not phylogenetically distinct from those of denitrifiers, and phylogenetic analysis suggests that the nirK and norB genes in ammonia-oxidizing bacteria have been subject to lateral transfer.
氨氧化细菌被认为是具有气候重要性的微量气体一氧化二氮（N₂O）的一个重要来源。亚硝酸还原酶（nirK）和一氧化氮还原酶（norB）的基因被推测与一氧化二氮的产生有关，已在几种氨氧化细菌中得到鉴定，但在可能在土壤氨氧化群落中占主导地位的亚硝化螺菌属菌株中尚未发现。在本研究中，在几种培养的亚硝化螺菌属物种中检测到了nirK和norB基因的序列，并将这些基因的多样性和系统发育与其他氨氧化细菌和经典反硝化细菌中的进行了比较。从亚硝化螺菌属获得的nirK和norB基因序列具有多样性，并且似乎比16S rRNA基因和功能性氨单加氧酶（amoA）基因的保守性更低。一些亚硝化螺菌属物种的nirK和norB基因在系统发育上与反硝化细菌的基因并无明显差异，系统发育分析表明氨氧化细菌中的nirK和norB基因发生了横向转移。
