两株耐重金属普罗维登斯菌属异养硝化好氧反硝化菌的分离及脱氮特性

Isolation and nitrogen removal characteristics of two heavy metal-tolerant heterotrophic nitrifying-aerobic denitrifying strains of Providencia

摘要:

【背景】近年来，随着畜禽养殖规模的扩大，产生大量富含重金属离子的养殖污水，导致传统脱氮技术受到限制，降低污水脱氮效率。【目的】从污水处理厂污水和污泥中分离筛选耐重金属异养硝化-好氧反硝化细菌，研究其脱氮效率。【方法】通过菌落和细胞形态特征观察、16S rRNA基因序列鉴定菌种。分别以NH₄⁺-N、NO₃⁻-N、NO₂⁻-N为唯一氮源考察菌株的硝化及反硝化性能，并考察在重金属(Cu、Zn、Cd、Cr、Pb)存在下菌株的氨氮去除能力。【结果】从污水和污泥中筛选出2株异养硝化-好氧反硝化菌WS-A和WH-K，经鉴定为普罗维登斯菌属(Providencia)。菌株WS-A、WH-K均能在以(NH₄)₂SO₄、NaNO₃、NaNO₂为唯一氮源的培养基中生长，并且48 h内NH₄⁺-N去除率为84.93%和84.48%，好氧反硝化作用NO₃⁻-N的去除率分别为82.5%和86.7%，NO₂⁻-N去除率分别为93.60%和93.84%。100 mg/L Zn²⁺胁迫下菌株WS-A、WH-K氨氮去除率达80%以上，1 000 mg/L的Cu²⁺和80 mg/L Cr³⁺、Cd²⁺、Pb²⁺胁迫下菌株WS-A、WH-K氨氮去除率为56%−77%。【结论】筛选出2株在5种重金属离子胁迫下仍表现良好脱氮性能的异养硝化好氧反硝化(heterotrophic nitrifying-aerobic denitrifying, HNAD)菌，初步探测了菌株的重金属耐受性，以便更好地为实际应用提供技术指导。

Abstract:

[Background] In recent years, with the expansion of the animal farming scale, a large amount of breeding sewage rich in heavy metal ions is produced. The conventional nitrogen removal technologies have limitations in treating such sewage, demonstrating reduced nitrogen removal efficiency. [Objective] To isolate and screen heavy metal-tolerant heterotrophic nitrifying-aerobic denitrifying bacteria from sewage and sludge of a sewage treatment plant and study the nitrogen removal efficiency of the isolates. [Methods] We identified the strains by observing the morphological characteristics of colonies and cells and analyzing the 16S rRNA gene sequences. With NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N as the only nitrogen sources, the nitrification and denitrification performance of the strains, as well as the removal capacity of ammonia nitrogen in the presence of heavy metals (Cu, Zn, Cd, Cr, and Pb), was investigated. [Results] Two strains of heterotrophic nitrifying-aerobic denitrifying bacteria were isolated from sewage and sludge, identified as Providencia sp., and named WS-A and WH-K. Both WS-A and WH-K could grow in the media with (NH₄)₂SO₄, NaNO₃, or NaNO₂ as the only nitrogen source, with the NH₄⁺-N removal rates of 84.93% and 84.48% within 48 h, the NO₃⁻-N removal rates of 82.5% and 86.7%, and the NO₂⁻-N removal rates of 93.60% and 93.84%, respectively. WS-A and WH-K showcased the ammonia nitrogen removal rate more than 80% in the presence of 100 mg/L Zn²⁺ and the ammonia nitrogen removal rate within the range of 56% to 77% in the presence of 1 000 mg/L Cu²⁺ or 80 mg/L Cr³⁺, Cd²⁺,and Pb²⁺. [Conclusion] We screened out two strains of heterotrophic nitrifying-aerobic denitrifying bacteria showing good nitrogen removal performance under the stress of five heavy metal ions and examined their heavy metal tolerance. The findings provide technical guidance for practical application.