AUTHOR=Huang Xuejiao , Luo Yuwen , Luo Luo , Xie Deti , Li Zhenlun 

TITLE=The nitrite reductase encoded by nirBDs in Pseudomonas putida Y-9 influences ammonium transformation

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.982674

DOI=10.3389/fmicb.2022.982674

ISSN=1664-302X

ABSTRACT=<p>It is unknown whether <italic>nirBDs</italic>, which conventionally encode an NADH nitrite reductase, play other novel roles in nitrogen cycling. In this study, we explored the role of <italic>nirBDs</italic> in the nitrogen cycling of <italic>Pseudomonas putida</italic> Y-9. <italic>nirBDs</italic> had no effect on organic nitrogen transformation by strain Y-9. The △<italic>nirBD</italic> strain exhibited higher ammonium removal efficiency (90.7%) than the wild-type strain (76.1%; <italic>P</italic> &lt; 0.05) and lower end gaseous nitrogen (N<sub>2</sub>O) production. Moreover, the expression of <italic>glnA</italic> (control of the ammonium assimilation) in the △<italic>nirBD</italic> strain was higher than that in the wild-type strain (<italic>P</italic> &lt; 0.05) after being cultured in ammonium-containing medium. Furthermore, nitrite noticeably inhibited the ammonium elimination of the wild-type strain, with a corresponding removal rate decreasing to 44.8%. However, no similar impact on ammonium transformation was observed for the △<italic>nirBD</italic> strain, with removal efficiency reaching 97.5%. In conclusion, <italic>nirBDs</italic> in strain Y-9 decreased the ammonium assimilation and increased the ammonium oxidation to nitrous oxide.</p>