厌氧铵氧化过程中关键酶及相关分子标记在生态学研究中的应用进展

厌氧铵氧化是由微生物介导的氮素循环过程中的重要途径之一。近20年来,通过对厌氧铵氧化细菌生态学、基因组学和生理代谢特性的探索,人们对其微生物学机制已经有了较多的认识:厌氧铵氧化细菌通过亚硝酸盐还原酶将亚硝酸根离子还原为一氧化氮,进而与铵离子结合在联氨合成酶的作用下生成联氨,最后通过联氨氧化酶的催化产生终产物氮气。同时,对参与这些过程的关键酶及其功能基因的认识有助于选择新的分子标记,从而为研究厌氧铵氧化细菌的多样性和分子生态学特征提供新的工具,以弥补16S rRNA基因特异性相对较低且难以与生态功能关联等方面的不足。对目前已知的参与厌氧铵氧化过程的3种关键酶的研究历程和现状进行了评述,并总结了利用3种功能基因进行厌氧铵氧化细菌生态学研究的最新进展。

Review of the key enzymes in the anammox process and ecological inferences derived from related molecular markers

Anammox (anaerobic ammonium oxidation) is a microbial-mediated pathway that plays an essential role in nitrogen cycling. Over the past twenty years, the characteristics of the anammox process and microbial metabolism have been determined by ecological, physiological, and genomic investigations. Anammox bacteria oxidize nitrite to nitric oxide via nitrite reductase, after which the nitric oxide further combines with ammonium to synthesize hydrazine, which is catalyzed by hydrazine oxidase to produce nitrogen gas. Functional genes encoding key enzymes in the anammox process have provided new molecular markers for ecological studies of anammox bacteria, and are potentially superior to 16S rRNA genes in linking anammox diversity to ecological functions. In this review, research on the key enzymes involved in the anammox process is introduced, and major advances in the molecular ecology of anammox bacteria are summarized based on functional gene investigations.