一株兼性厌氧反硝化细菌的分离与鉴定

Isolation and Identification of a Facultative Anaerobic Denitrifying Bacteria

本项目从水产养殖的实际需求出发,尝试对具有水质净化作用的硝化细菌及其群落中其它菌种进行分离和鉴定。本实验中利用硝化细菌可氧化铵根获得能量的营养特性,采用四种简单的无机盐(包括NH₄Cl、NaHCO₃、Na₂HPO₄、NaCl)及琼脂糖配置了分离硝化细菌群落的简易培养基。在饲养热带观赏鱼采用的28℃、潮湿条件下,经过10天培养后,长出了两种不同的菌落。经16S rRNA测序和核酸序列比对,可知其中一种菌落为硝化细菌Alcaligenes faecalis,另一种为兼性厌氧菌Dysgonomonas的新种。该新种的16S rRNA序列与其系统发生树上最接近的已命名物种Dysgonomonas oryzarvi (CBA7536品系,序列号MN646999.1)有93.29%相似度。其系统发生树由TreeView X软件构建。在以上描述的生长条件下,该种经推断为反硝化细菌,通过还原Alcaligenes faecalis的硝化产物获得能量。

Nitrifying bacteria have been playing an important role in aquaculture because of their ability to purify water by oxidizing ammonium salt. Using this special feature, a series of selective culture mediums for them and other bacteria in their community have been designed. The culture mediums contain agarose, NaCl, Na₂HPO₄ and different amounts of NH₄Cl and NaHCO₃. After 10-day culture under 28℃, two different colonies are distinguished and isolated. Through 16S rRNA sequencing and alignment, the species forming the larger one of the colonies is recognized to be Alcaligenes faecalis, a kind of nitrifying bacteria;and the other species is identified as a new species of Dysgonomonas, a genus of facultative anaerobic bacteria. The 16S rRNA sequence of the new species shows 93.29% similarity with Dysgonomonas oryzarvi strain CBA7536 (MN646999.1), which is currently its phylogenetically closest species that has been named. The phylogenetic tree of the new species is constructed by TreeView X. Under the culture conditions described above, the novel Dysgonomonas strain acts as denitrifying bacteria which reduces the nitrification products of Alcaligenes faecalis to produce energy.