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Giordano M, Goodman CA, Huang F, Raven JA, Ruan Z. A mechanistic study of the influence of nitrogen and energy availability on the NH4+ sensitivity of nitrogen assimilation in Synechococcus. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5596-5611. [PMID: 35595516 PMCID: PMC9467657 DOI: 10.1093/jxb/erac219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/19/2022] [Indexed: 05/23/2023]
Abstract
In most algae, NO3- assimilation is tightly controlled and is often inhibited by the presence of NH4+. In the marine, non-colonial, non-diazotrophic cyanobacterium Synechococcus UTEX 2380, NO3- assimilation is sensitive to NH4+ only when N does not limit growth. We sequenced the genome of Synechococcus UTEX 2380, studied the genetic organization of the nitrate assimilation related (NAR) genes, and investigated expression and kinetics of the main NAR enzymes, under N or light limitation. We found that Synechococcus UTEX 2380 is a β-cyanobacterium with a full complement of N uptake and assimilation genes and NAR regulatory elements. The nitrate reductase of our strain showed biphasic kinetics, previously observed only in freshwater or soil diazotrophic Synechococcus strains. Nitrite reductase and glutamine synthetase showed little response to our growth treatments, and their activity was usually much higher than that of nitrate reductase. NH4+ insensitivity of NAR genes may be associated with the stimulation of the binding of the regulator NtcA to NAR gene promoters by the high 2-oxoglutarate concentrations produced under N limitation. NH4+ sensitivity in energy-limited cells fits with the fact that, under these conditions, the use of NH4+ rather than NO3- decreases N-assimilation cost, whereas it would exacerbate N shortage under N limitation.
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Affiliation(s)
- Mario Giordano
- STU-UNIVPM Joint Algal Research Center, Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona 60131, Italy
- CMNS-Cell Biology and Molecular Genetics, 2107 Bioscience Research Building, University of Maryland, College Park, MD 20742-4407, USA
- Institute of Microbiology ASCR, Algatech, Trebon, Czech Republic
- National Research Council, Institute of Marine Science, Venezia, Italy
| | - Charles A Goodman
- CMNS-Cell Biology and Molecular Genetics, 2107 Bioscience Research Building, University of Maryland, College Park, MD 20742-4407, USA
| | - Fengying Huang
- STU-UNIVPM Joint Algal Research Center, Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China
| | - John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5 DA, UK
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Ultimo NSW 2007, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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Li YY, Chen XH, Xie ZX, Li DX, Wu PF, Kong LF, Lin L, Kao SJ, Wang DZ. Bacterial Diversity and Nitrogen Utilization Strategies in the Upper Layer of the Northwestern Pacific Ocean. Front Microbiol 2018; 9:797. [PMID: 29922238 PMCID: PMC5996900 DOI: 10.3389/fmicb.2018.00797] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 04/10/2018] [Indexed: 11/13/2022] Open
Abstract
Nitrogen (N) is a primary limiting nutrient for bacterial growth and productivity in the ocean. To better understand bacterial community and their N utilization strategy in different N regimes of the ocean, we examined bacterial diversity, diazotrophic diversity, and N utilization gene expressions in the northwestern Pacific Ocean (NWPO) using a combination of high-throughput sequencing and real-time qPCR methods. 521 and 204 different operational taxonomic units (OTUs) were identified in the 16s rRNA and nifH libraries from nine surface samples. Of the 16s rRNA gene OTUs, 11.9% were observed in all samples while 3.5 and 15.9% were detected only in N-sufficient and N-deficient samples. Proteobacteria, Cyanobacteria and Bacteroidetes dominated the bacterial community. Prochlorococcus and Pseudoalteromonas were the most abundant at the genus level in N-deficient regimes, while SAR86, Synechococcus and SAR92 were predominant in the Kuroshio-Oyashio confluence region. The distribution of the nifH gene presented great divergence among sampling stations: Cyanobacterium_UCYN-A dominated the N-deficient stations, while clusters related to the Alpha-, Beta-, and Gamma-Proteobacteria were abundant in other stations. Temperature was the main factor that determined bacterial community structure and diversity while concentration of NOX-N was significantly correlated with structure and distribution of N2-fixing microorganisms. Expression of the ammonium transporter was much higher than that of urea transporter subunit A (urtA) and ferredoxin-nitrate reductase, while urtA had an increased expression in N-deficient surface water. The predicted ammonium transporter and ammonium assimilation enzymes were most abundant in surface samples while urease and nitrogenase were more abundant in the N-deficient regions. These findings underscore the fact that marine bacteria have evolved diverse N utilization strategies to adapt to different N habitats, and that urea metabolism is of vital ecological importance in N-deficient regimes.
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Affiliation(s)
- Yuan-Yuan Li
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Xiao-Huang Chen
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Zhang-Xian Xie
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Dong-Xu Li
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Peng-Fei Wu
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Ling-Fen Kong
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Lin Lin
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Shuh-Ji Kao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
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