一株耐盐的卓贝儿氏菌(Zobellella sp.)的分离鉴定及其硝酸盐还原能力

Isolation, identification and nitrate reduction ability of a salt-tolerant strain of Zobellella sp.

摘要:

【背景】好氧反硝化是指在有氧条件下进行反硝化作用，使得硝化和反硝化过程能够在同一反应器中同时发生，是废水脱氮最具竞争力的技术。红树林湿地中蕴藏着丰富的微生物资源，分布着大量好氧反硝化微生物。【目的】了解耐盐微生物的脱氮机制，为含盐废水生物脱氮的工程实践提供理论依据，对一株分离于红树林湿地中的耐盐好氧细菌A63的硝酸盐异化还原能力进行分析。【方法】利用形态学特征及16S rRNA基因序列测定分析，对其种属进行了鉴定，采用单因子实验测定该菌在不同环境因子下的硝酸盐还原能力，并对其反硝化脱氮条件进行了优化。【结果】初步判定该菌株为卓贝儿氏菌(Zobellella sp.)，其能在盐度0%?10%、pH 5.0?10.0、温度20?40 °C范围内进行反硝化脱氮和硝酸盐异化还原为氨(dissimilatory nitrate reduction to ammonium，DNRA)作用。菌株A63最适生长碳源为柠檬酸钠(1.2 g/L)，适宜脱氮盐度为3%、pH 7.0?7.5、温度30?35 °C，且C/N为10。在最适脱氮条件下，该菌株12 h内能将培养基中208.8 mg/L硝态氮降至0，且仅有少量铵态氮生成，无亚硝态氮积累，脱氮率高达99%。此外，该菌株在高盐度、低C/N比、弱酸性和低温等不利生境中DNRA作用显著。【结论】细菌A63生长范围宽，脱氮效率显著，适用于海水养殖废水处理。研究为今后开发高效含盐废水生物脱氮工艺奠定了基础，对于加深氮素转化规律的认识、丰富生物脱氮理论有着重要意义。

Abstract:

[Background] Aerobic denitrification is carried out under aerobic conditions, so that nitrification and denitrification can occur at the same time in the same reactor, which is the most competitive technology for nitrogen removal from wastewater. Mangrove wetlands are rich in microbial resources and a large number of aerobic denitrifying microorganisms are distributed. [Objective] In order to understand the denitrification mechanism of salt-tolerant microorganisms and provide a theoretical basis for the engineering practice of biological denitrification of salt-bearing wastewater, a salt-tolerant aerobic bacteria A63 was isolated from the mangrove wetland and its nitrate reduction ability was analyzed. [Methods] The species were identified by morphological characteristics and 16S rRNA gene sequencing. The nitrate reduction ability of the strain under different environmental factors was determined by single factor experiment, and its denitrification performance was optimized. [Results] It was preliminarily determined that the strain belonged to the Zobellella sp. The strain can carry out denitrification and dissimilatory nitrate reduction to ammonium (DNRA) action in the range of salinity 0%?10%, pH 5.0?10.0 and temperature 20?40 °C. The optimum growth carbon source is sodium citrate (1.2 g/L), and the optimum salinity 3.0%, the pH is 7.0?7.5, the temperature is 30?35 °C and C/N is 10. Under the optimum denitrification condition, the strain could reduce 208.8 mg/l NO3?-N to 0 in the medium within 12 hours, and only a small amount of ammonium nitrogen was produced. There was no accumulation of nitrite nitrogen, and the denitrification rate was as high as 99%. Furthermore, the strain had a significant effect on DNRA in adverse habitats such as high salinity, low C/N ratio, weak acidity and low temperature. [Conclusion] The strain A63 has a wide range of growth and remarkable nitrogen removal efficiency, so it is suitable for the treatment of mariculture wastewater. The present study lays a foundation for the development of high efficiency biological nitrogen removal process for salty wastewater in the future, and is of great significance to deepen the understanding of nitrogen transformation law and enrich the theory of biological nitrogen removal.