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Fan Q, Xia C, Zeng X, Wu Z, Guo Y, Du Q, Tu M, Liu X, Pan D. Effect and potential mechanism of nitrite reductase B on nitrite degradation by Limosilactobacillus fermentum RC4. Curr Res Food Sci 2024; 8:100749. [PMID: 38694558 PMCID: PMC11061237 DOI: 10.1016/j.crfs.2024.100749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/04/2024] Open
Abstract
Nitrite has the potential risk of hypoxic poisoning or cancer in pickled food. In our previous study, Limosilactobacillus fermentum (L. fermentum) RC4 is effective in nitrite degradation by producing nitrite reductase B (NirB). To investigate the detailed mechanism from the genome, response, and regulation of NirB, the whole-genome sequence of L. fermentum RC4 was analyzed, the L. fermentum-EGFP-nirB with enhanced green fluorescent protein (EGFP) labeled the nitrite reductase large subunit nirB, and the recombined L. fermentum-NirB with overexpression NirB strain was conducted. The key genes within the dominant metabolism pathways may be involved in stress tolerance to regulate the degrading process. The green fluorescence density of EGFP indicated that NirB activity has a threshold and peaked under 300 mg/L nitrite concentration. NirB overexpressed in L. fermentum RC4 boosted the enzyme activity by 39.6% and the degradation rate by 10.5%, when fermented in 300 mg/L for 40 h, compared to the control group. RNA-seq detected 248 differential genes mainly enriched in carbohydrate, amino acid, and energy metabolism. The ackA gene for pyruvate metabolism and the mtnN gene for cysteine metabolism were up-regulated. NirB regulates these genes to produce acid and improve stress resistance for L. fermentum RC4 to accelerate nitrite degradation.
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Affiliation(s)
- Qing Fan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Chaoran Xia
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Xiaoqun Zeng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Zhen Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Yuxing Guo
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Qiwei Du
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Maolin Tu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
| | - Xinanbei Liu
- College of Resources and Environment, Baoshan University, Baoshan, China
| | - Daodong Pan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food Science and Engineering, Ningbo University, Ningbo, China
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, China
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Shi J, Che J, Sun X, Zeng X, Du Q, Guo Y, Wu Z, Pan D. Transcriptomic Responses to Nitrite Degradation by Limosilactobacillus fermentum RC4 and Effect of ndh Gene Overexpression on Nitrite Degradation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:13156-13164. [PMID: 37624070 DOI: 10.1021/acs.jafc.3c03066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
The excessive nitrite residue may increase cell damage and cancer risk. Limosilactobacillu fermentum RC4 exhibited excellent nitrite degradation ability. Herein, the molecular mechanism of nitrite degradation by L. fermentum RC4 was studied by integrating scanning electron microscopy analysis, transcriptomics, and gene overexpression. The results demonstrated that the gene profile of RC4 cultured in MRS broth with 0, 100, and 300 mg/L NaNO2 varied considerably; RC4 responded to nitrite degradation by regulating pyruvate metabolism, energy synthesis, nitrite metabolism, redox equilibrium, protein protection, and signaling. High nitrite concentrations affected the morphology of RC4 with a longer phenotype, rough and wrinkle cell and reduced cell surface hydrophobicity. Moreover, an up-regulated expression of gene ndh encoding NADH dehydrogenase, which provides electrons for nitrite reduction by catalyzing NADH, was identified when RC4 was exposed to nitrite. Overexpression of ndh in RC4 increased the nitrite degradation rate by 2-9.5% in MRS broth with 100 mg/L NaNO2. Thus, the findings of this study could be helpful for the application of L. fermentum to reduce nitrite residues and improve food safety in fermented food products.
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Affiliation(s)
- Jingjing Shi
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Jiahao Che
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Xiaoqian Sun
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Xiaoqun Zeng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Qiwei Du
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Yuxing Guo
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210097, China
| | - Zhen Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Daodong Pan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo 315211, China
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
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Yılmaz H, Erdoğan EM, Ergenekon P, Özkan M. Comparison of ion selectivities of nitrite channel NirC and water channel aquaporin. World J Microbiol Biotechnol 2023; 39:120. [PMID: 36918441 DOI: 10.1007/s11274-023-03553-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 02/20/2023] [Indexed: 03/16/2023]
Abstract
nirC gene coding for the nitrite channel of E. coli K12 was cloned into the pET28a vector and expressed in E. coli BL21 cells. 28.5 kDa NirC monomer was purified from membrane components of E. coli. Selectivity of NirC for different ions including nitrite, nitrate, sulfate, formate, and acetate anions, and a divalent cation, magnesium, was compared with that of bacterial aquaporin from Halomonas elongata. Water and ion permeability values were determined by measuring the light scattering rates of proteoliposomes containing NirC and aquaporins during their water loss and gain. NirC shows a selective permeability to nitrite and is more resistant to the entry of other anions as compared to aquaporin. The single channel permeability of NirC for nitrite is about 10-fold that of a single aquaporin channel. Both aquaporin and NirC channel proteins were impermeable to MgCl2 and (NH4)2SO4 and their permeability to other tested ions was remarkably lower as compared to nitrite ions. The study also presents the 3D model and channel characteristics of NirC. The translocation channel of E. coli NirC is determined to be larger, and its length is shorter than aquaporin channels. Although the NirC channel throat is more hydrophobic than aquaporin, its water permeability is almost equal to that of aquaporin. The hydrophobic nature of the NirC channel might play an important role in the selective permeability of the channel for nitrite ions.
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Affiliation(s)
- Hilal Yılmaz
- Environmental Engineering Department, Gebze Technical University, 41400, Kocaeli, Turkey
| | - Esra Meşe Erdoğan
- Environmental Engineering Department, Gebze Technical University, 41400, Kocaeli, Turkey
| | - Pınar Ergenekon
- Environmental Engineering Department, Gebze Technical University, 41400, Kocaeli, Turkey
| | - Melek Özkan
- Environmental Engineering Department, Gebze Technical University, 41400, Kocaeli, Turkey.
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Liu Y, Zhang Y, Huang Y, Niu J, Huang J, Peng X, Peng F. Spatial and temporal conversion of nitrogen using Arthrobacter sp. 24S4-2, a strain obtained from Antarctica. Front Microbiol 2023; 14:1040201. [PMID: 36876078 PMCID: PMC9975570 DOI: 10.3389/fmicb.2023.1040201] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/30/2023] [Indexed: 02/17/2023] Open
Abstract
According to average nucleotide identity (ANI) analysis of the complete genomes, strain 24S4-2 isolated from Antarctica is considered as a potential novel Arthrobacter species. Arthrobacter sp. 24S4-2 could grow and produce ammonium in nitrate or nitrite or even nitrogen free medium. Strain 24S4-2 was discovered to accumulate nitrate/nitrite and subsequently convert nitrate to nitrite intracellularly when incubated in a nitrate/nitrite medium. In nitrogen-free medium, strain 24S4-2 not only reduced the accumulated nitrite for growth, but also secreted ammonia to the extracellular under aerobic condition, which was thought to be linked to nitrite reductase genes nirB, nirD, and nasA by the transcriptome and RT-qPCR analysis. A membrane-like vesicle structure was detected in the cell of strain 24S4-2 by transmission electron microscopy, which was thought to be the site of intracellular nitrogen supply accumulation and conversion. This spatial and temporal conversion process of nitrogen source helps the strain maintain development in the absence of nitrogen supply or a harsh environment, which is part of its adaption strategy to the Antarctic environment. This process may also play an important ecological role, that other bacteria in the environment would benefit from its extracellular nitrogen source secretion and nitrite consumption characteristics.
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Affiliation(s)
- Yixuan Liu
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
| | - Yumin Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Yudi Huang
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
| | - Jingjing Niu
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
| | - Jun Huang
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
| | - Xiaoya Peng
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
| | - Fang Peng
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan, China
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Huang R, Meng T, Liu G, Gao S, Tian J. Simultaneous nitrification and denitrification in membrane bioreactor: Effect of dissolved oxygen. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 323:116183. [PMID: 36088763 DOI: 10.1016/j.jenvman.2022.116183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
Membrane bioreactor with the floc activated sludge (mixed liquor suspended solids (MLSS) = 7500 mg/L) was constructed in this work for simultaneously nitrification and denitrification (SND). The effect of dissolved oxygen (DO) on SND process and the nitrogen pathways were investigated. The average TN removal efficiencies were 63.05%, 91.17%, 87.04% and 70.02% for DO 0.5, 1, 2 and 3 mg/L systems, respectively. The effluent ammonia concentration was continuously lower than 5.0 mg/L when the DO was higher than 1 mg/L. Nitrogen in DO 1 and DO 2 mg/L systems was mainly removed via the SND process. The rise of DO concentration increased the abundance of nitrite oxidizing bacteria (NOB) and Nitrospira was the predominant NOB in all the four MBRs. Dechloromonas and Azoarcus were the dominant denitrifying bacteria (DNB) in DO 1 systems responsible for nitrite denitrification. The dominant aerobic DNB Pseudomonas also contributed SND via nitrate denitrification and was little affected by DO changes. Nitrate reductase was the main enzyme for the reduction of NO3--N to NO2--N, and narG was the main responsible gene. Nitrite oxidoreductase was the main enzyme for the oxidation of NO2--N to NO3--N, and nxrA was the main responsible gene in all the four MBR systems.
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Affiliation(s)
- Rui Huang
- School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, 300401, China; Guangdong GDH Water Co. Ltd, Shenzhen, 518021, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Tongyang Meng
- School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Gaige Liu
- School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, 300401, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
| | - Shanshan Gao
- School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Jiayu Tian
- School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, 300401, China
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Yılmaz H, İbici HN, Erdoğan EM, Türedi Z, Ergenekon P, Özkan M. Nitrite is reduced by nitrite reductase NirB without small subunit NirD in Escherichia coli. J Biosci Bioeng 2022; 134:393-398. [PMID: 36068114 DOI: 10.1016/j.jbiosc.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 11/26/2022]
Abstract
The assimilatory nitrite reductase enzyme NirB and small subunit NirD genes encoded in nir operon in Escherichia coli were cloned into the pET28a vector, and the recombinant enzyme was characterized for the first time. Docking of NirB with NirD, NADH, NO2-, NO3-, and CHO2- was performed using docking modeling programs. Methyl viologen and sodium dithionite were used as electron couples, and the amount of reduced nitrite was measured to calculate enzyme activity. NirB is the main enzyme and shows high activity with or without NirD. However, the inclusion of NirD into the enzyme solution at a ratio of 1NirD:2NirB resulted in 10% higher nitrite reductase activity. The enzyme tends to aggregate in the absence of β-mercaptoethanol, which causes the conversion of tetrameric NirB to monomeric form, and the NirB enzyme shows its highest activity in monomeric form. The optimum temperature for enzyme activity was 37 °C and the optimum pH was found to be 7.0. Km and Vmax values of NirB were calculated as 9833 μM and 416.67 μmol NO2- reduced min-1 mg-1. Enzyme activity decreased by 55% and 50% in the presence of 100 mM nitrate and formate, respectively. The presence of 25 mM Cd2+ protected the enzyme at room temperature and the enzyme showed 10% higher activity in the presence of cadmium.
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Affiliation(s)
- Hilal Yılmaz
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
| | - Hilal Nisanur İbici
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
| | - Esra Meşe Erdoğan
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
| | - Zeynep Türedi
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
| | - Pınar Ergenekon
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
| | - Melek Özkan
- Gebze Technical University, Environmental Engineering Department, 41400 Kocaeli, Turkey.
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Huang YY, Liang MH, Zhao S, Chen SM, Liu JS, Liu DM, Lu YZ. Isolation, expression, and biochemical characterization: nitrite reductase from Bacillus cereus LJ01. RSC Adv 2020; 10:37871-37882. [PMID: 35515171 PMCID: PMC9057199 DOI: 10.1039/d0ra06129h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/23/2020] [Indexed: 11/24/2022] Open
Abstract
Biological remediation of toxic oxygen-containing anions such as nitrate that are common in the environment is of great significance. Therefore, it is necessary to understand the specific role of nitrate and nitrite reductase in the bioremediation process. Bacillus cereus LJ01, which was isolated from traditional Chinese soybean paste, effectively degraded nitrite (such as NaNO2) at 0–15 mmol L−1 in LB medium. Moreover, the nitrite-degrading active substance (ASDN) was isolated and purified from B. cereus LJ01. The nitrite-degrading activity of nitrite reductase (named LJ01-NiR) was 4004.89 U mg−1. The gene encoding the assimilation of nitrite reductase in B. cereus LJ01 was cloned and overexpressed in E. coli. The purified recombinant LJ01-NiR has a wide range of activities under temperature (20–60 °C), pH (6.5–8.0) and metal ions (Fe3+, Fe2+, Cu2+, Mn2+, and Al3+). Kinetic parameters of LJ01-NiR, including the values of Km and Vmax were 1.38 mM and 2.00 μmol g−1 min−1, respectively. The results showed that LJ01-NiR could degrade nitrite with or without an electron donor. In addition, sequence analysis revealed that LJ01-NiR was a ferredoxin-dependent nitrite reductase given the presence of conserved [Fe4–S4] cluster and heme-binding domain. The nitrite ion binds to the LJ01-NiR active site by forming three hydrogen bonds with the residues ASN72, ALA133 and ASN140. Due to its high nitrite-degrading activity, LJ01-NiR could potentially be used for environmental pollution treatment. Biological remediation of toxic oxygen-containing anions such as nitrite in the environment is of great significance. Bacillus cereus LJ01 showed the activity of degradation for nitrite. the enzyme NiR from LJ01 can degrade the nitrite in vitro.![]()
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Affiliation(s)
- Yan-Yan Huang
- School of Food Science and Engineering, South China University of Technology 381 Wushan Road Guangzhou Guangdong 510640 People's Republic of China
| | - Ming-Hua Liang
- School of Food Science and Engineering, South China University of Technology 381 Wushan Road Guangzhou Guangdong 510640 People's Republic of China
| | - Shan Zhao
- School of Food Science and Engineering, South China University of Technology 381 Wushan Road Guangzhou Guangdong 510640 People's Republic of China
| | - Si-Min Chen
- School of Food Science and Engineering, South China University of Technology 381 Wushan Road Guangzhou Guangdong 510640 People's Republic of China
| | - Jin-Song Liu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences 190 Kaiyuan Avenue, Science Park, Huangpu District Guangzhou 510530 People's Republic of China
| | - Dong-Mei Liu
- School of Food Science and Engineering, South China University of Technology 381 Wushan Road Guangzhou Guangdong 510640 People's Republic of China
| | - Yong-Zhi Lu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences 190 Kaiyuan Avenue, Science Park, Huangpu District Guangzhou 510530 People's Republic of China
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Huang X, Weisener CG, Ni J, He B, Xie D, Li Z. Nitrate assimilation, dissimilatory nitrate reduction to ammonium, and denitrification coexist in Pseudomonas putida Y-9 under aerobic conditions. BIORESOURCE TECHNOLOGY 2020; 312:123597. [PMID: 32506044 DOI: 10.1016/j.biortech.2020.123597] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
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 15N 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.
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Affiliation(s)
- Xuejiao Huang
- Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China
| | - Christopher G Weisener
- Great Lakes Institute of Environmental Research, University of Windsor, Ontario N9B3P4, Canada
| | - Jiupai Ni
- Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China
| | - Binghui He
- Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China
| | - Deti Xie
- Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China
| | - Zhenlun Li
- Chongqing Key Laboratory of Soil Multiscale Interfacial Process, Southwest University, Chongqing 400716, China.
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