Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China.
Great Lakes Institute of Environmental Research, University of Windsor, Ontario N9B3P4, Canada.
Bioresour Technol. 2020 Sep;312:123597. doi: 10.1016/j.biortech.2020.123597. Epub 2020 May 30.
The specific nitrate reduction pathway in Pseudomonas putida Y-9 under aerobic conditions was studied. Strain Y-9 removed 82% of the nitrate accompanied by an accumulation of ammonium and a decrease of total nitrogen. Ammonium inhibited nitrate transformation (removal efficiency was 22.65%), illustrating that nitrate assimilation exists in strain Y-9. The detectable ammonium in the supernatant during the nitrate reduction process came from intracellular locations in strain Y-9. The nirBD that encodes nitrite reductase had an important role in strain growth and ammonium production. A N isotope experiment demonstrated that strain Y-9 can conduct dissimilatory nitrate reduction to ammonium (DNRA) and nirBD controls this process. This further indicated that the loss of total nitrogen is due to denitrification. All results highlighted that strain Y-9 performs simultaneous nitrate assimilation, DNRA, and denitrification under aerobic conditions, and nirBD controls the assimilation and DNRA process. Thereinto, nitrate assimilation dominates the removal of nitrate.
研究了好氧条件下恶臭假单胞菌 Y-9 中的特定硝酸盐还原途径。菌株 Y-9 去除了 82%的硝酸盐，同时积累了铵盐并降低了总氮。铵盐抑制了硝酸盐的转化（去除效率为 22.65%），说明硝酸盐同化作用存在于菌株 Y-9 中。在硝酸盐还原过程中，上清液中可检测到的铵盐来自菌株 Y-9 细胞内的位置。编码亚硝酸盐还原酶的 nirBD 在菌株生长和铵盐产生中起重要作用。N 同位素实验表明，菌株 Y-9 可以进行异化硝酸盐还原为铵盐（DNRA），nirBD 控制该过程。这进一步表明总氮的损失是由于反硝化作用。所有结果都强调了菌株 Y-9 在好氧条件下同时进行硝酸盐同化、DNRA 和反硝化作用，而 nirBD 控制同化和 DNRA 过程。其中，硝酸盐同化作用主导了硝酸盐的去除。
