耐冷菌水生从毛单胞菌(Comamonas aquatilis) NY3的高效脱氮特性及其Cu2+耐受性

Nitrogen removal characteristics and Cu2+ tolerance of psychrotolerant Comamonas aquatilis NY3

摘要:

【背景】 低温条件下含重金属废水的生物脱氮处理面临严峻挑战，其中铜离子(Cu²⁺)会显著影响微生物的脱氮效率，目前关于耐冷脱氮菌在Cu²⁺胁迫下的脱氮特性及其耐受机制的研究尚不充分。【目的】 探究耐冷脱氮菌水生从毛单胞菌(Comamonas aquatilis) NY3的脱氮特性和Cu²⁺耐受性，为低温含Cu²⁺废水的生物处理提供理论指导。【方法】 通过批量试验研究了不同浓度Cu²⁺对菌株NY3脱氮效率的影响，在高浓度Cu²⁺下研究该菌株转化无机氮过程中的电子传递系统活性与氮代谢关键酶的活性变化，同时测定外源硫化物添加是否有助于缓解Cu²⁺对该菌株生长和代谢的抑制。【结果】 Cu²⁺显著影响了菌株NY3的脱氮能力，当不添加Cu²⁺时，菌株NY3对铵态氮、硝态氮和亚硝态氮的去除率分别为99.98%、100.00%、100.00%，添加8.0 mg/L Cu²⁺后，其去除率分别降低至51.56%、55.70%、0，同时，电子传递系统活性也从0.306、0.115、0.124 μg/(g·min)降至0，氨单加氧酶(ammonia monooxygenase, AMO)和硝酸还原酶(nitrate reductase, NR)活性分别从0.260 U/mg和0.610 U/mg降低到0.250 U/mg和0.260 U/mg。添加45.0 mg/L NaHS和50.0 mg/L Na₂S后，可显著缓解菌株NY3在Cu²⁺胁迫下的生长和代谢抑制作用，145 mg/L NaHS使菌株对铵态氮和硝态氮的去除率分别提高了48.17%和70.94%。【结论】 菌株NY3对Cu²⁺胁迫具有一定的耐受性，过量Cu²⁺对菌株NY3的异养硝化和好氧反硝化脱氮有抑制作用，可通过添加适量的外源硫缓解Cu²⁺对菌株NY3的抑制强度，从而增加Cu²⁺胁迫下的脱氮效率，可为低温环境下采用微生物处理含有Cu²⁺的氮污染废水提供理论依据。

Abstract:

[Background] Biodenitrification of wastewater containing heavy metals under low temperature conditions is facing severe challenges. Copper ions (Cu²⁺) can significantly affect the denitrification efficiency of microorganisms. At present, the research remains limited regarding the denitrification characteristics and tolerance mechanism of psychrotolerant denitrifiers under Cu²⁺ stress. [Objective] To investigate the denitrification characteristics and Cu²⁺ tolerance of Comamonas aquatilis NY3, providing theoretical guidance for the biological treatment of low temperature wastewater containing Cu²⁺. [Methods] We conducted batch experiments to study the effects of different concentrations of Cu²⁺ on the nitrogen removal efficiency of strain NY3. The activities of the electron transfer system and the key enzymes in nitrogen metabolism during the transformation of inorganic nitrogen by strain NY3 were studied under high-concentration Cu²⁺. In addition, we determined whether exogenous sulphide addition helped to alleviate the inhibition on the growth and metabolism of this strain by Cu²⁺. [Results] Cu²⁺ significantly affected the nitrogen removal ability of strain NY3. When Cu²⁺ was not added, the removal rates of ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen by strain NY3 were 99.98%, 100.00%, and 100.00%, respectively. After the addition of 8.0 mg/L Cu²⁺, the removal rates decreased to 51.56%, 55.70%, and 0, respectively. At the same time, the activity of the electron transfer system also decreased from 0.306, 0.115, and 0.124 μg/(g·min) to 0. The activities of ammonia monooxygenase and nitrate reductase decreased from 0.260 U/mg and 0.610 U/mg to 0.250 U/mg and 0.260 U/mg, respectively. The addition of 45.0 mg/L NaHS and 50.0 mg/L Na₂S significantly alleviated the inhibition of Cu²⁺ stress on the growth and metabolism of strain NY3. Specifically, 145 mg/L NaHS increased the removal rates of ammonium nitrogen and nitrate nitrogen by 48.17% and 70.94%, respectively. [Conclusion] Strain NY3 has certain tolerance to Cu²⁺ stress. Excessive Cu²⁺ has inhibitory effects on heterotrophic nitrification and aerobic denitrification of strain NY3. The inhibition of strain NY3 by Cu²⁺ can be alleviated by the addition of appropriate amounts of exogenous sulphur, which thereby increases the denitrification efficiency under Cu²⁺ stress. The findings provide a theoretical basis for the treatment of nitrogen-contaminated wastewater containing Cu²⁺ by microorganisms in a low-temperature environment.