title: Expression of the nirS, hzsA, and hdh Genes in Response to Nitrite Shock and Recovery in Candidatus Kuenenia stuttgartiensis.
abstract: In this study, Candidatus Kuenenia stuttgartiensis were subjected to distinct nitrite shocks (66 (control), 200, 300, 400, and 500 mg N/L), and the responses of mRNA levels of cytochrome cd1 nitrite/nitric oxide oxidoreductase (nirS), hydrazine synthase (hzsA), and hydrazine dehydrogenase (hdh) were assessed. Changes in the hydrazine dehydrogenase (HDH) protein level were monitored. At 200 mg NO2(-)-N/L, the normalized specific anaerobic ammonium-oxidizing activity (nSAA) slightly increased relative to the control despite a significant decrease in nirS, hzsA, and hdh mRNA levels. When nitrite increased to 300 and 400 mg N/L, increased nirS, hzsA, and hdh mRNA levels were observed, but the nSAA decreased, relative to the 200 mg NO2(-)-N/L exposure. HDH protein detection revealed that Candidatus Kuenenia stuttgartiensis attempted to yield high enzyme levels by stimulating mRNA synthesis to resist the nitrite-induced stress. On 500 mg NO2(-)-N/L shock, the nirS, hzsA, and hdh mRNA levels decreased, alongside decreased nSAA and HDH levels. Although the mRNA levels did not always coincide with activities, our findings advance understanding of the mechanisms that anammox bacteria use to cope with nitrite inhibition at the transcriptional and translational levels, which will improve the diagnostic accuracy of bioreactor failures when nitrite accumulation occurs.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Siping Road, Shanghai 200092, P. R. China.
authors.forename: Yayi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Siping Road, Shanghai 200092, P. R. China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Siping Road, Shanghai 200092, P. R. China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Siping Road, Shanghai 200092, P. R. China.
authors.forename: Ximao
authors.initials: X
authors.lastname: Lin
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology , Beijing 100124, P. R. China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ma
authors.affiliation: School of Civil, Environmental and Architectural Engineering, Korea University , Anam-Dong, Seongbuk-Gu, Seoul 136-713, South Korea.
authors.forename: Hee-Deung
authors.initials: HD
authors.lastname: Park
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Siping Road, Shanghai 200092, P. R. China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yan
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D064751:Ammonium Compounds; D009573:Nitrites