AUTHOR=Mao Jiwei , Zhao Ruojin , Li Yiyi , Qin Wenpan , Wu Shengchun , Xu Weiping , Jin Peng , Zheng Zhanwang 

TITLE=Nitrogen removal capability and mechanism of a novel low-temperature-tolerant simultaneous nitrification-denitrification bacterium Acinetobacter kyonggiensis AKD4

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1349152

DOI=10.3389/fmicb.2024.1349152

ISSN=1664-302X

ABSTRACT=<p>A low-temperature-tolerant simultaneous nitrification-denitrification bacterial strain of <italic>Acinetobacter kyonggiensis</italic> (AKD4) was identified. It showed high efficiency in total nitrogen (TN) removal (92.45% at 10°C and 87.51% at 30°C), indicating its excellent low-temperature tolerance. Transcriptomic analysis revealed possible metabolic mechanisms under low-temperature stress. Genes involved in cell growth, including ATP synthase (<italic>atpADGH</italic>), amino acid (<italic>glyA</italic>, <italic>dctA</italic>, and <italic>ilvE</italic>), and TCA cycle metabolism (<italic>gltA</italic>, <italic>fumC</italic>, and <italic>mdh</italic>) were remarkably upregulated from 1.05–3.44-fold at 10°C, suggesting that their actions enhance survivability at low temperatures. The expression levels of genes associated with nitrogen assimilation (<italic>glnAE</italic>, <italic>gltBD</italic>, and <italic>gdhA</italic>), nitrogen metabolism regulation (<italic>ntrC</italic>, <italic>glnB</italic>, and <italic>glnD</italic>), and denitrification processes (<italic>napA</italic>) were increased from 1.01–4.38-fold at 10°C, which might have contributed to the bacterium’s highly efficient nitrogen removal performance at low temperatures. Overall, this study offers valuable insights into transcriptome, and enhances the comprehension of the low-temperature-tolerant mechanism of simultaneous nitrification and denitrification processes.</p>