一株中度嗜盐异养硝化-好氧反硝化盐单胞菌5505的分离和氮转化特性

Isolation and nitrogen transformation characterization of a moderately halophilic nitrification-aerobic denitrification strain Halomonas sp. 5505

摘要:

基于异养硝化-好氧反硝化菌的生物脱氮技术可有效去除污水中的氮素，但随着废水盐度增加，生物脱氮效率急剧下降。为解决高盐废水生物脱氮难题，从我国新疆盐湖筛选出一株耐盐的异养硝化-好氧反硝化菌5505菌株，通过菌落特征观察、生理生化特征和细菌16S rRNA基因序列分析，并以NH₄⁺-N、NO₃^–-N和NO₂^–-N为单一或混合氮源开展单因素实验，研究菌株的硝化、反硝化性能及氮代谢途径。结果表明，菌株5505为盐单胞菌(Halomonas sp.)，在NaCl浓度为1%–25% (质量体积分数)范围内可正常生长，在3%–8%范围内可高效发挥除氮功能，在最适浓度8%条件下，对NH₄⁺-N、NO₃^–-N和NO₂^–-N去除率分别为100.0%、94.11%和74.43%。氮平衡分析发现，菌株5505的氮去除主要通过同化作用，最高可占去除量的62.68%，在多氮源共存时，优先利用氨氮，推测其脱氮路径为NH₄⁺→NH₂OH→NO₂^–→NO₃^–→NO₂^–→NO/N₂O/N₂。本研究为高盐含氮废水的生物净化提供了高效的耐盐菌种资源，对丰富生物脱氮理论及提高污水处理厂脱氮性能具有重要意义。

Abstract:

The biological nitrogen removal technology utilizing heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has shown effectiveness in wastewater treatment. However, the nitrogen removal efficiency of HN-AD bacteria significantly decreases as the salinity increases. To tackle the challenge of treating high-salt and high-nitrogen wastewater, we isolated a moderately halophilic HN-AD strain 5505 from a salt lake in Xinjiang. The strain was identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence. Single-factor experiments were carried out with NH₄⁺-N, NO₃^--N, and NO₂^--N as sole or mixed nitrogen sources to study the nitrifying effect, denitrifying effect, and nitrogen metabolism pathway of the strain. The strain was identified as Halomonas sp.. It can grow in the presence of 1%-25% (W/V) NaCl and exhibited efficient nitrogen removal ability in the presence of 3%-8% NaCl. At the optimal NaCl concentration (8%), the strain showed the NH₄⁺-N, NO₃^--N and NO₂^--N removal rates of 100.0%, 94.11% and 74.43%, respectively. Strain 5505 removed inorganic nitrogen mainly by assimilation, which accounted for over 62.68% of total nitrogen removal. In the presence of mixed nitrogen sources, strain 5505 showed a preference for utilizing ammonia, with a potential HN-AD pathway of NH₄⁺→NH₂OH→NO₂^-→NO₃^-→NO₂^-→NO/N₂O/N₂. The findings provide efficient salt-tolerant bacterial resources, enhance our understanding of biological nitrogen removal, and contribute to the nitrogen removal efficiency improvement in the treatment of high-salt and high-nitrogen wastewater.