Abstract

The nitrite removal pathway in Acinetobacter sp. TX5 was explored through the key gene identification and the corresponding enzyme purification, after which the capability to reduce nitrite by immobilized beads was investigated in a fixed-bed reactor. Results revealed that a nosZ gene encoding nitrous oxide reductase (N₂OR) exists in TX5 cells, and a N₂OR responsible for the reduction of N₂O to N₂ was purified successfully with a molecular weight of 70.05 kDa, a purification fold of 16.30 and a recovery rate of 5.17%. For TX5 immobilization, the optimal values of polyvinyl alcohol (PVA), spent mushroom substrate (SMS) and Aci (TX5) obtained by response surface methodology (RSM) were 6.32%, 2.92% and 4.57%, respectively. In a fixed-bed reactor packed with immobilized TX5, the removal efficiency (RE) achieved 90% (at 50h) for NO- 2-N and 85% (at 96h) for total nitrogen (TN). On the basis of these results, a nitrite removal pathway in TX5 was proposed. Overall, Acinetobacter sp. TX5 might be a promising candidate for nitrite removal with an ability to suppress N₂O accumulation.

摘要

不动杆菌中亚硝酸盐的去除途径 通过关键基因鉴定和相应的酶纯化来探索TX5，然后在固定床反应器中研究固定化珠粒还原亚硝酸盐的能力。结果显示TX5细胞中存在一个编码一氧化二氮还原酶（N ₂ OR）的nosZ基因，一个N ₂ OR负责将N ₂ O还原为N ₂纯化成功，分子量为70.05 kDa，纯化倍数为16.30，回收率为5.17％。对于TX5固定，通过响应表面方法（RSM）获得的聚乙烯醇（PVA），废蘑菇底物（SMS）和Aci（TX5）的最佳值分别为6.32％，2.92％和4.57％。在装有固定化TX5的固定床反应器中，对于NO-2-N，去除效率（RE）达到90％（在50h），对于总氮（TN）达到85％（在96h）。基于这些结果，提出了TX5中亚硝酸盐的去除途径。总体而言，不动杆菌属。TX5可能具有去除N ₂ O积累的能力，是去除亚硝酸盐的有希望的候选者。