草坪土壤异养硝化菌的分离筛选及硝化产物特征分析

Separation and Selection of Heterotrophic Nitrifying Bacteria from Lawn Soil and Their Nitrification Products Characteristics

从早熟禾草坪土壤中分离出两株异养硝化菌,将菌株16S r DNA测序结果在Gen Bank中进行同源性对比确定菌种,用无机氮源(NH_4^+-N和NO_3^--N)在适宜条件下测定两个菌株的硝化能力,分析中间产物、反硝化作用和N2O排放特征。结果表明,分离到的异养硝化菌属于假单胞杆菌属(Pseudomonas sp.),两个菌株的16S r DNA片段长度分别为1 448和1 460 bp,命名为Pseudomonas sp.BJ和Pseudomonas sp.DJ,Gen Bank登录号分别为MF001078和MF001079;两个菌株对无机氮的氧化能力很强,培养24 h内BJ和DJ菌株对铵态氮的总硝化率分别为96.61%和97.06%,最大硝化速率分别为21.97和18.90mg·L^(-1)·h^(-1)。但两个菌株的反硝化能力不强,最大反硝化速率分别为0.99和1.00 mg·L^(-1)·h^(-1);两个菌株的代谢途径是NH_4^+→NH_2OH→NO_2^-→NO_3^-,DJ菌株的最终产物以NO_3-^-N为主,积累量高于BJ菌株(P<0.05)。BJ菌株的N_2O排放量显著高于DJ菌株(P<0.05)。

In this experiment,two heterotrophic nitrifying bacteria isolated from lawn soil were identified by comparing 16 S rDNA sequence to homologous species published on the Gen Bank. The nitrification function of these two bacteria were detected by measuring intermediate products,denitrification process and N2O emission characteristics under inorganic nitrogen sources（NH4^＋-N and NO3^--N）. The results showed that the two heterotrophic nitrifying bacteria were identified as Pseudomonas sp.,16 S r DNA fragment length were 1 448 and 1 460 bp and named as Pseudomonas sp. BJ and Pseudomonas sp. DJ,respectively. Gen Bank accession number were MF001078 and MF001079 for Pseudomonas sp. BJ and Pseudomonas sp. DJ. The two strains have a strong oxidation ability with inorganic nitrogen,ammonium removal efficiencies were 96.61% and 97.06%,respectively. The maximum nitrification rate were 21.97 and 18.90 mg · L^-1· h^-1. Denitrification ability of two bacteria were not efficient,the maximum denitrification rate were 0.99 and 1.00 mg · L^-1· h^-1,respectively. Metabolic pathways of the two strains can be simplified to a large extent as NH4^＋ → NH2 OH → NO2^-→ NO3^-. NO3^--N was the main intermediate products of strain DJ,and its content was much higher than that of strain BJ（P〈0.05）. The content of N2O produced by strain BJ was significantly higher than that of strain DJ（P〈0.05）.