Pseudomonas alcaliphila AD-28的脱氮性能及其关键酶活性

【背景】异养硝化-好氧反硝化菌由于能够同时实现硝化反硝化作用而备受关注,但由于菌的种类不同,其脱氮途径不尽相同,研究菌株脱氮关键酶的种类及其活性可以推测菌株的脱氮途径,从而为菌株在生产上的应用提供技术支撑。【目的】研究Pseudomonas alcaliphila AD-28的脱氮性能及其关键酶的活性,为菌株脱氮分子机理研究奠定基础。【方法】以柠檬酸钠为碳源,以硫酸铵、亚硝酸钠、硝酸钾为氮源,研究菌株AD-28的脱氮性能并检测其关键酶氨单加氧酶(AMO)、羟胺氧化还原酶(HAO)、亚硝酸盐还原酶(NIR)、硝酸盐还原酶(NAR)的酶活性。【结果】菌株AD-28培养24h的菌密度(OD600)可达1.971,对初始浓度为18.85mg/L的氨氮、26.13mg/L的硝酸盐氮、19.47mg/L的亚硝酸盐氮、66.11 mg/L的总氮去除率均达到96%以上;关键酶AMO、HAO、NIR和NAR的比活力分别为0.028、0.003、0.011、0.027 U/mg。【结论】Pseudomonas alcaliphila AD-28能同时进行异养硝化-好养反硝化作用,该菌在AMO作用下将NH4+-N氧化为羟胺,然后由HAO氧化为NO2--N,NO2--N和NO3--N在NIR、NAR等酶的催化作用下脱氮。

Nitrogen removal characteristic and key enzymes activity of Pseudomonas alcaliphila AD-28

Background] Heterotrophic nitrifying-aerobic denitrifying microorganisms have received more and more attention, because they achieve the vision of simultaneous nitrification and denitrification in one system. The nitrogen removal pathway is different along with different bacteria. While the nitrogen metabolic pathway of bacteria is direct correlation with the type and activity of nitrogen elimination enzyme. So find out the nitrogen removal pathway of Pseudomonas alcaliphila AD-28 will provide technical support in application. Objective] In order to reveal the nitrogen removal mechanism, the nitrogen removal characteristic and key enzymes for nitrogen degradation of Pseudomonas alcaliphila AD-28 were studied. Methods] The nitrogen removal characteristic of strain AD-28 was investigated when sodium citrate was used as carbon source, ammonium sulfate, sodium nitrite and potassium nitrate were used as nitrogen sources. At the same time, the activities of key enzymes-ammonia monooxygenase (AMO), hydroxylamine oxidoreductase (HAO), nitrite reductase (NIR) and nitrate reductase (NAR) were measured. Results] After 24 h treatment by strain AD-28, bacteria density (OD600) reached 1.971, the degradation rates of NH4+-N, NO3?-N, NO2?-N and total nitrogen (TN) were all exceeded 96% when the initial concentrations were 18.85, 26.13, 19.47, 66.11 mg/L, respectively. The corresponding specific activities of AMO, HAO, NIR and NAR were 0.028, 0.003, 0.011, 0.027 U/mg, respectively. Conclusion] The results suggest that AD-28 is a simultaneous heterotrophic nitrification-aerobic denitrification strain. The nitrogen removal pathway of the stain was deduced as following. NH4+-N was oxidized to NH2OH by AMO, then NH2OH oxidized to NO2?-N by HAO, NO2?-N and NO3?-N removed from the medium by NIR and NAR.