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Li JF, Yang LY, Zhang Z, Huang XR, Li H, Li S, Yang XR. Asymbiotic Nitrogen Fixation in the Phyllosphere of Urban Green Spaces. Curr Microbiol 2025; 82:276. [PMID: 40319203 DOI: 10.1007/s00284-025-04250-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2025] [Accepted: 04/17/2025] [Indexed: 05/07/2025]
Abstract
Biological nitrogen fixation (BNF) is an important source of nitrogen in ecosystems. Compared to symbiotic nitrogen-fixing microorganisms, free-living diazotrophic bacteria have a broader distribution and greater diversity, demonstrating greater potential for application. Leaf surfaces constitute one of the largest microbial reservoirs on Earth, harboring a variety of free-living diazotrophic bacteria, contributing significantly to plant N acquisition and growth. The distribution patterns, abundance, diversity, and the environmental variables affecting the asymbiotic nitrogen fixation (ANF) rates of free-living diazotrophic bacteria of non-leguminous plants in urban green spaces were investigated using high-throughput sequencing of nifH gene amplicons and the acetylene reduction method. Both green space type and plant species significantly impact ANF rates and nifH gene abundance in the phyllosphere, with green space type having a more pronounced effect. Leaf metal elements iron (Fe), molybdenum (Mo), and the free-living diazotrophic bacteria of the genus Skermanella collectively influence the ANF rates in the phyllosphere of urban green spaces. Linear regression analysis revealed that metal elements Fe, Mo, and potassium (K) in the leaves were significantly positive correlated with the diversity of the free-living diazotrophic bacteria and the abundance of the N-fixing gene nifH. The alpha diversity and symbiotic network structure of the free-living diazotrophic bacterial community in the phyllosphere indicated a significant negative correlation between human disturbance and environmental perturbation and the biodiversity and network complexity of these bacteria. This study provides a crucial foundation for understanding the nitrogen-fixing functions of microbes in urban ecosystems and their contributions to the nitrogen cycle.
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Affiliation(s)
- Jian-Feng Li
- College of Environment and Safety Engineering, Fuzhou University, Fuzhou, 350116, China
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Le-Yang Yang
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Zhao Zhang
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Xin-Rong Huang
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Hu Li
- College of Environment and Safety Engineering, Fuzhou University, Fuzhou, 350116, China
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Shun Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Xiao-Ru Yang
- College of Environment and Safety Engineering, Fuzhou University, Fuzhou, 350116, China.
- State Key Laboratory for Ecological Security of Regions and Cities, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
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2
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Liao N, Zhu Z, Wang C, Sun J, Zhou M, Zhang R. Fine-scale diazotroph community structure in the continental slope of the northern South China sea. MARINE ENVIRONMENTAL RESEARCH 2025; 204:106926. [PMID: 39765078 DOI: 10.1016/j.marenvres.2024.106926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2024] [Revised: 12/19/2024] [Accepted: 12/20/2024] [Indexed: 02/09/2025]
Abstract
Diazotrophs have made significant contributions to marine nitrogen cycles. However, their distribution patterns and determined mechanisms have not been fully understood, particularly at the small regional scales. Here, the diazotrophic community structure by different sample sizes (0.2-10 μm and >10 μm), evaluated using high-throughput sequencing of the nifH gene, and the abundance of four typical diazotroph phylotypes, estimated by quantitative PCR of the nifH gene, were investigated on the continental slope of the northern South China Sea at a horizontal spatial resolution of 47.19-71.63 km. The results showed that Proteobacteria and Cyanobacteria were the dominant diazotrophic groups, which mainly contributed by Gamma-proteobacteria and Trichodesmium, respectively. Trichodesmium occupied the large-particle samples in the surface water, while other diazotrophs were nonuniformly distributed across water depths, particle sizes, and stations, indicating the heterogeneous distribution of diazotrophs at fine scales. Vertical profiles of environmental factors, especially the profile data of Fe concentration, were investigated, and the results indicated that temperature, dissolved inorganic nitrogen, and N:Fe were strongly correlated to diazotroph abundance and distribution of Trichodesmium and γ-24774A11. In the transect influenced by the Pearl River plume, γ-24774A11 nifH gene abundance significantly decreased than in other stations, indicating the important role of Pearl River plume in shaping the diazotrophic community structure. These findings advance our understanding of diazotrophic biogeography at the smaller regional scales.
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Affiliation(s)
- Nan Liao
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Zhu Zhu
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, 200030, China.
| | - Chunxue Wang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Jun Sun
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan, 430074, China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China.
| | - Meng Zhou
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, 200030, China.
| | - Ruifeng Zhang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, 200030, China
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3
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Sheng Y, Zeng X, Zhao L, Li Y. Editorial: Microbial involvement in biogeochemical cycling and contaminant transformations at land-water ecotones. Front Microbiol 2024; 15:1525521. [PMID: 39703713 PMCID: PMC11655481 DOI: 10.3389/fmicb.2024.1525521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2024] [Accepted: 11/21/2024] [Indexed: 12/21/2024] Open
Affiliation(s)
- Yizhi Sheng
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
| | - Xiangfeng Zeng
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, China
| | - Linduo Zhao
- Prairie Research Institute-Illinois Sustainable Technology Centre/Illinois State Water Survey, University of Illinois at Urbana Champaign, Champaign, IL, United States
| | - Yongbin Li
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, China
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4
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Shen H, Wan XS, Zou W, Dai M, Xu MN, Kao SJ. Light-driven integration of diazotroph-derived nitrogen in euphotic nitrogen cycle. Nat Commun 2024; 15:9193. [PMID: 39448610 PMCID: PMC11502797 DOI: 10.1038/s41467-024-53067-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Accepted: 09/30/2024] [Indexed: 10/26/2024] Open
Abstract
The bioavailable nitrogen fixed by diazotrophs is critical for sustaining productivity in the oligotrophic ocean. Despite this, understanding how diazotroph-derived nitrogen integrates into the nitrogen cycle within the euphotic zone remains unknown. Here, we investigated nitrogen fixation rates in the particulate and dissolved fractions within the euphotic zone of the North Pacific Subtropical Gyre. Our findings reveal the proportion of nitrogen fixation rates in the dissolved fraction increases with depth. Light manipulation experiments uncover that reduced light levels can stimulate the net release of diazotroph-derived nitrogen, aligning with our depth-related observations. Furthermore, we identify two distinct transfer pathways vertically associated with light-driven ecological niches. Specifically, the released diazotroph-derived nitrogen is transferred to non-diazotrophic plankton in the upper layers. Meanwhile, in the lower layers, it contributes to the nitrification process. Our results underscore the high bioavailability of diazotroph-derived nitrogen and its rapid integration into the nitrogen cycle through multiple pathways within the well-lit ocean.
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Affiliation(s)
- Hui Shen
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Xianhui S Wan
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Wenbin Zou
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Minhan Dai
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Min N Xu
- State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Science and Engineering, Hainan University, Haikou, China.
| | - Shuh-Ji Kao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.
- State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Science and Engineering, Hainan University, Haikou, China.
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5
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Qiu GW, Zheng WC, Yang HM, Wang YY, Qi X, Huang D, Dai GZ, Shi H, Price NM, Qiu BS. Phosphorus deficiency alleviates iron limitation in Synechocystis cyanobacteria through direct PhoB-mediated gene regulation. Nat Commun 2024; 15:4426. [PMID: 38789507 PMCID: PMC11126600 DOI: 10.1038/s41467-024-48847-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Iron and phosphorus are essential nutrients that exist at low concentrations in surface waters and may be co-limiting resources for phytoplankton growth. Here, we show that phosphorus deficiency increases the growth of iron-limited cyanobacteria (Synechocystis sp. PCC 6803) through a PhoB-mediated regulatory network. We find that PhoB, in addition to its well-recognized role in controlling phosphate homeostasis, also regulates key metabolic processes crucial for iron-limited cyanobacteria, including ROS detoxification and iron uptake. Transcript abundances of PhoB-targeted genes are enriched in samples from phosphorus-depleted seawater, and a conserved PhoB-binding site is widely present in the promoters of the target genes, suggesting that the PhoB-mediated regulation may be highly conserved. Our findings provide molecular insights into the responses of cyanobacteria to simultaneous iron/phosphorus nutrient limitation.
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Affiliation(s)
- Guo-Wei Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Wen-Can Zheng
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Hao-Ming Yang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Yu-Ying Wang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Xing Qi
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Da Huang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Guo-Zheng Dai
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Huazhong Shi
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409, USA
| | - Neil M Price
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, Québec, H3A 1B1, Canada
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China.
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6
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Kramer BJ, Turk-Kubo K, Zehr JP, Gobler CJ. Intensification of harmful cyanobacterial blooms in a eutrophic, temperate lake caused by nitrogen, temperature, and CO 2. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 915:169885. [PMID: 38190910 DOI: 10.1016/j.scitotenv.2024.169885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/01/2024] [Accepted: 01/01/2024] [Indexed: 01/10/2024]
Abstract
Warmer temperatures can significantly increase the intensity of cyanobacterial harmful algal blooms (CHABs) in eutrophic freshwater ecosystems. However, few studies have examined the effects of CO2 enrichment in tandem with elevated temperature and/or nutrients on cyanobacterial taxa in freshwater ecosystems. Here, we observed changes in the biomass of cyanobacteria, nutrients, pH, and carbonate chemistry over a two-year period in a shallow, eutrophic freshwater lake and performed experiments to examine the effects and co-effects of CO2, temperature, and nutrient enrichment on cyanobacterial and N2-fixing (diazotrophic) communities assessed via high throughput sequencing of the 16S rRNA and nifH genes, respectively. During both years, there were significant CHABs (50-500 μg cyanobacterial chlorophyll-a L-1) and lake CO2 levels were undersaturated (≤300 μatm pCO2). NH4+ significantly increased the net growth rates of cyanobacteria as well as the biomass of the diazotrophic cyanobacterial order Nostocales under elevated and ambient CO2 conditions. In a fall experiment, the N2 fixation rates of Nostocales were significantly higher when populations were enriched with CO2 and P, relative to CO2-enriched populations that were not amended with P. During a summer experiment, N2 fixation rates increased significantly under N and CO2 - enriched conditions relative to N-enriched and ambient CO2 conditions. Nostocales dominated the diazotrophic communities of both experiments, achieving the highest relative abundance under CO2-enriched conditions when N was added in the first experiment and when CO2 and temperature were elevated in the second experiment, when N2 fixation rates also increased significantly. Collectively, this study indicates that N promotes cyanobacterial blooms including those formed by Dolichospermum and that the biomass and N2 fixation rates of diazotrophic cyanobacterial taxa may benefit from enhanced CO2 levels in eutrophic lakes.
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Affiliation(s)
- Benjamin J Kramer
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
| | - Kendra Turk-Kubo
- Oceans Sciences Department, University of California at Santa Cruz, CA, United States
| | - Jonathan P Zehr
- Oceans Sciences Department, University of California at Santa Cruz, CA, United States
| | - Christopher J Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States.
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7
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Schiksnis C, Xu M, Saito MA, McIlvin M, Moran D, Bian X, John SG, Zheng Q, Yang N, Fu F, Hutchins DA. Proteomics analysis reveals differential acclimation of coastal and oceanic Synechococcus to climate warming and iron limitation. Front Microbiol 2024; 15:1323499. [PMID: 38444803 PMCID: PMC10912551 DOI: 10.3389/fmicb.2024.1323499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/30/2024] [Indexed: 03/07/2024] Open
Abstract
In many oceanic regions, anthropogenic warming will coincide with iron (Fe) limitation. Interactive effects between warming and Fe limitation on phytoplankton physiology and biochemical function are likely, as temperature and Fe availability affect many of the same essential cellular pathways. However, we lack a clear understanding of how globally significant phytoplankton such as the picocyanobacteria Synechococcus will respond to these co-occurring stressors, and what underlying molecular mechanisms will drive this response. Moreover, ecotype-specific adaptations can lead to nuanced differences in responses between strains. In this study, Synechococcus isolates YX04-1 (oceanic) and XM-24 (coastal) from the South China Sea were acclimated to Fe limitation at two temperatures, and their physiological and proteomic responses were compared. Both strains exhibited reduced growth due to warming and Fe limitation. However, coastal XM-24 maintained relatively higher growth rates in response to warming under replete Fe, while its growth was notably more compromised under Fe limitation at both temperatures compared with YX04-1. In response to concurrent heat and Fe stress, oceanic YX04-1 was better able to adjust its photosynthetic proteins and minimize the generation of reactive oxygen species while reducing proteome Fe demand. Its intricate proteomic response likely enabled oceanic YX04-1 to mitigate some of the negative impact of warming on its growth during Fe limitation. Our study highlights how ecologically-shaped adaptations in Synechococcus strains even from proximate oceanic regions can lead to differing physiological and proteomic responses to these climate stressors.
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Affiliation(s)
- Cara Schiksnis
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Min Xu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China
| | - Mak A. Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Matthew McIlvin
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Dawn Moran
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Xiaopeng Bian
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Seth G. John
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Qiang Zheng
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, China
| | - Nina Yang
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
- Marine Policy Center, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Feixue Fu
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - David A. Hutchins
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
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8
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Sun X, Xiao Y, Yong C, Sun H, Li S, Huang H, Jiang H. Interactions between the nitrogen-fixing cyanobacterium Trichodesmium and siderophore-producing cyanobacterium Synechococcus under iron limitation. ISME COMMUNICATIONS 2024; 4:ycae072. [PMID: 38873030 PMCID: PMC11171426 DOI: 10.1093/ismeco/ycae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/07/2024] [Indexed: 06/15/2024]
Abstract
As diazotrophic cyanobacteria of tremendous biomass, Trichodesmium continuously provide a nitrogen source for carbon-fixing cyanobacteria and drive the generation of primary productivity in marine environments. However, ocean iron deficiencies limit growth and metabolism of Trichodesmium. Recent studies have shown the co-occurrence of Trichodesmium and siderophore-producing Synechococcus in iron-deficient oceans, but whether siderophores secreted by Synechococcus can be used by Trichodesmium to adapt to iron deficiency is not clear. We constructed a mutant Synechococcus strain unable to produce siderophores to explore this issue. Synechococcus filtrates with or without siderophores were added into a Trichodesmium microbial consortium consisting of Trichodesmium erythraeum IMS 101 as the dominant microbe with chronic iron deficiency. By analyzing the physiological phenotype, metagenome, and metatranscriptome, we investigated the interactions between the nitrogen-fixing cyanobacterium Tricodesmium and siderophore-producing cyanobacterium Synechococcus under conditions of iron deficiency. The results indicated that siderophores secreted by Synechococcus are likely to chelate with free iron in the culture medium of the Trichodesmium consortium, reducing the concentration of bioavailable iron and posing greater challenges to the absorption of iron by Trichodesmium. These findings revealed the characteristics of iron-competitive utilization between diazotrophic cyanobacteria and siderophore-producing cyanobacteria, as well as potential interactions, and provide a scientific basis for understanding the regulatory effects of nutrient limitation on marine primary productivity.
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Affiliation(s)
- Xumei Sun
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 1 Jintang Road, Zhuhai, Guangdong, 519000, People’s Republic of China
| | - Yan Xiao
- School of Life Sciences, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei, 430079, People’s Republic of China
| | - Chengwen Yong
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
| | - Hansheng Sun
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
| | - Shuangqing Li
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
| | - Hailong Huang
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 1 Jintang Road, Zhuhai, Guangdong, 519000, People’s Republic of China
| | - Haibo Jiang
- School of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang, 315211, People’s Republic of China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 1 Jintang Road, Zhuhai, Guangdong, 519000, People’s Republic of China
- School of Life Sciences, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei, 430079, People’s Republic of China
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9
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Zhu YG, Peng J, Chen C, Xiong C, Li S, Ge A, Wang E, Liesack W. Harnessing biological nitrogen fixation in plant leaves. TRENDS IN PLANT SCIENCE 2023; 28:1391-1405. [PMID: 37270352 DOI: 10.1016/j.tplants.2023.05.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 06/05/2023]
Abstract
The importance of biological nitrogen fixation (BNF) in securing food production for the growing world population with minimal environmental cost has been increasingly acknowledged. Leaf surfaces are one of the biggest microbial habitats on Earth, harboring diverse free-living N2-fixers. These microbes inhabit the epiphytic and endophytic phyllosphere and contribute significantly to plant N supply and growth. Here, we summarize the contribution of phyllosphere-BNF to global N cycling, evaluate the diversity of leaf-associated N2-fixers across plant hosts and ecosystems, illustrate the ecological adaptation of N2-fixers to the phyllosphere, and identify the environmental factors driving BNF. Finally, we discuss potential BNF engineering strategies to improve the nitrogen uptake in plant leaves and thus sustainable food production.
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Affiliation(s)
- Yong-Guan Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
| | - Jingjing Peng
- State Key Laboratory of Nutrient Use and Management, College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, China Agricultural University, Beijing, 100193, China
| | - Cai Chen
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Chao Xiong
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Shule Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Anhui Ge
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, SIBS, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Ertao Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, SIBS, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Werner Liesack
- Max Planck Institute for Terrestrial Microbiology, Marburg, 35043, Germany
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10
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Browning TJ, Moore CM. Global analysis of ocean phytoplankton nutrient limitation reveals high prevalence of co-limitation. Nat Commun 2023; 14:5014. [PMID: 37591895 PMCID: PMC10435517 DOI: 10.1038/s41467-023-40774-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 08/09/2023] [Indexed: 08/19/2023] Open
Abstract
Nutrient availability limits phytoplankton growth throughout much of the global ocean. Here we synthesize available experimental data to identify three dominant nutrient limitation regimes: nitrogen is limiting in the stratified subtropical gyres and in the summertime Arctic Ocean, iron is most commonly limiting in upwelling regions, and both nutrients are frequently co-limiting in regions in between the nitrogen and iron limited systems. Manganese can be co-limiting with iron in parts of the Southern Ocean, whilst phosphate and cobalt can be co-/serially limiting in some settings. Overall, an analysis of experimental responses showed that phytoplankton net growth can be significantly enhanced through increasing the number of different nutrients supplied, regardless of latitude, temperature, or trophic status, implying surface seawaters are often approaching nutrient co-limitation. Assessments of nutrient deficiency based on seawater nutrient concentrations and nutrient stress diagnosed via molecular biomarkers showed good agreement with experimentally-assessed nutrient limitation, validating conceptual and theoretical links between nutrient stoichiometry and microbial ecophysiology.
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Affiliation(s)
- Thomas J Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research, Kiel, 24148, Germany.
| | - C Mark Moore
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK.
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11
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Luo W, Luo YW. Diurnally dynamic iron allocation promotes N 2 fixation in marine dominant diazotroph Trichodesmium. Comput Struct Biotechnol J 2023; 21:3503-3512. [PMID: 37484493 PMCID: PMC10362294 DOI: 10.1016/j.csbj.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/15/2023] [Accepted: 07/04/2023] [Indexed: 07/25/2023] Open
Abstract
Trichodesmium is the dominant photoautotrophic dinitrogen (N2) fixer (diazotroph) in the ocean. Iron is an important factor limiting growth of marine diazotrophs including Trichodesmium mainly because of high iron content of its N2-fixing enzyme, nitrogenase. However, it still lacks a quantitative understanding of how dynamic iron allocation among physiological processes acts to regulate growth and N2 fixation in Trichodesmium. Here, we constructed a model of Trichodesmium trichome in which intracellular iron could be dynamically re-allocated in photosystems and nitrogenase during the daytime. The results demonstrate that the dynamic iron allocation enhances modeled N2 fixation and growth rates of Trichodesmium, especially in iron-limited conditions, albeit having a marginal impact under high iron concentrations. Although the reuse of iron during a day is an apparent cause that dynamic iron allocation can benefit Trichodesmium under iron limitation, our model reveals two important mechanisms. First, the release of iron from photosystems downregulates the intracellular oxygen (O2) production and reduces the demand of respiratory protection, a process that Trichodesmium wastefully respires carbohydrates to create a lower O2 window for N2 fixation. Hence, more carbohydrates can be used in growth. Second, lower allocation of iron to nitrogenase during early daytime, a period when photosynthesis is active and intracellular O2 is high, reduces the amount of iron that is trapped in the inactivated nitrogenase induced by O2. This mechanism further increases the iron use efficiency in Trichodesmium. Overall, our study provides mechanistic and quantitative insight into the diurnal iron allocation that can alleviate iron limitation to Trichodesmium.
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Jiang Z, Zhu Y, Sun Z, Zhai H, Zhou F, Yan X, Chen Q, Chen J, Zeng J. Size-fractionated N 2 fixation off the Changjiang Estuary during summer. Front Microbiol 2023; 14:1189410. [PMID: 37228373 PMCID: PMC10203160 DOI: 10.3389/fmicb.2023.1189410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 04/18/2023] [Indexed: 05/27/2023] Open
Abstract
Recent evidence has shown active N2 fixation in coastal eutrophic waters, yet the rate and controlling factors remain poorly understood, particularly in large estuaries. The Changjiang Estuary (CE) and adjacent shelf are characterized by fresh, nitrogen-replete Changjiang Diluted Water (CDW) and saline, nitrogen-depletion intruded Kuroshio water (Taiwan Warm Current and nearshore Kuroshio Branch Current), where N2 fixation may be contributed by different groups (i.e., Trichodesmium and heterotrophic diazotrophs). Here, for the first time, we provide direct measurement of size-fractionated N2 fixation rates (NFRs) off the CE during summer 2014 using the 15N2 bubble tracer method. The results demonstrated considerable spatial variations (southern > northern; offshore > inshore) in surface and depth-integrated NFRs, averaging 0.83 nmol N L-1 d-1 and 24.3 μmol N m-2 d-1, respectively. The highest bulk NFR (99.9 μmol N m-2 d-1; mostly contributed by >10 μm fraction) occurred in the southeastern East China Sea, where suffered from strong intrusion of the Kuroshio water characterized by low N/P ratio (<10) and abundant Trichodesmium (up to 10.23 × 106 trichomes m-2). However, low NFR (mostly contributed by <10 μm fraction) was detected in the CE controlled by the CDW, where NOx concentration (up to 80 μmol L-1) and N/P ratio (>100) were high and Trichodesmium abundance was low. The >10 μm fraction accounted for 60% of depth-integrated bulk NFR over the CE and adjacent shelf. We speculated that the present NFR of >10 μm fraction was mostly supported by Trichodesmium. Spearman rank correlation indicated that the NFR was significantly positively correlated with Trichodesmium abundance, salinity, temperature and Secchi depth, but was negatively with turbidity, N/P ratio, NOx, and chlorophyll a concentration. Our study suggests that distribution and size structure of N2 fixation off the CE are largely regulated by water mass (intruded Kuroshio water and CDW) movement and associated diazotrophs (particularly Trichodesmium) and nutrient conditions.
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Affiliation(s)
- Zhibing Jiang
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resource, Hangzhou, China
- Key Laboratory of Nearshore Engineering Environment and Ecological Security of Zhejiang Province, Hangzhou, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Observation and Research Station of Marine Ecosystem in the Yangtze River Delta, Ministry of Natural Resources, Hangzhou, China
| | - Yuanli Zhu
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resource, Hangzhou, China
- Observation and Research Station of Marine Ecosystem in the Yangtze River Delta, Ministry of Natural Resources, Hangzhou, China
| | - Zhenhao Sun
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Hongchang Zhai
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Feng Zhou
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Observation and Research Station of Marine Ecosystem in the Yangtze River Delta, Ministry of Natural Resources, Hangzhou, China
| | - Xiaojun Yan
- Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, China
| | - Quanzhen Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Jianfang Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Jiangning Zeng
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resource, Hangzhou, China
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Sheng Y, Baars O, Guo D, Whitham J, Srivastava S, Dong H. Mineral-Bound Trace Metals as Cofactors for Anaerobic Biological Nitrogen Fixation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7206-7216. [PMID: 37116091 DOI: 10.1021/acs.est.3c01371] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Nitrogenase is the only known biological enzyme capable of reducing N2 to bioavailable NH3. Most nitrogenases use Mo as a metallocofactor, while alternative cofactors V and Fe are also viable. Both geological and bioinformatic evidence suggest an ancient origin of Mo-based nitrogenase in the Archean, despite the low concentration of dissolved Mo in the Archean oceans. This apparent paradox would be resolvable if mineral-bound Mo were bioavailable for nitrogen fixation by ancient diazotrophs. In this study, the bioavailability of mineral-bound Mo, V, and Fe was determined by incubating an obligately anaerobic diazotroph Clostridium kluyveri with Mo-, V-, and Fe-bearing minerals (molybdenite, cavansite, and ferrihydrite, respectively) and basalt under diazotrophic conditions. The results showed that C. kluyveri utilized mineral-associated metals to express nitrogenase genes and fix nitrogen, as measured by the reverse transcription quantitative polymerase chain reaction and acetylene reduction assay, respectively. C. kluyveri secreted chelating molecules to extract metals from the minerals. As a result of microbial weathering, mineral surface chemistry significantly changed, likely due to surface coating by microbial exudates for metal extraction. These results provide important support for the ancient origin of Mo-based nitrogenase, with profound implications for coevolution of the biosphere and geosphere.
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Affiliation(s)
- Yizhi Sheng
- Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 45056, United States
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Oliver Baars
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Dongyi Guo
- Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 45056, United States
| | - Jason Whitham
- Department of Plant and Molecular Biology, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Shreya Srivastava
- Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 45056, United States
| | - Hailiang Dong
- Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 45056, United States
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Wrightson L, Yang N, Mahaffey C, Hutchins DA, Tagliabue A. Integrating the impact of global change on the niche and physiology of marine nitrogen-fixing cyanobacteria. GLOBAL CHANGE BIOLOGY 2022; 28:7078-7093. [PMID: 36054414 PMCID: PMC9826025 DOI: 10.1111/gcb.16399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/05/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Marine nitrogen fixation is a major source of new nitrogen to the ocean, which interacts with climate driven changes to physical nutrient supply to regulate the response of ocean primary production in the oligotrophic tropical ocean. Warming and changes in nutrient supply may alter the ecological niche of nitrogen-fixing organisms, or 'diazotrophs', however, impacts of warming on diazotroph physiology may also be important. Lab-based studies reveal that warming increases the nitrogen fixation-specific elemental use efficiency (EUE) of two prevalent marine diazotrophs, Crocosphaera and Trichodesmium, thus reducing their requirements for the limiting nutrients iron and phosphorus. Here, we coupled a new diazotroph model based upon observed diazotroph energetics of growth and resource limitation to a state-of-the-art global model of phytoplankton physiology and ocean biogeochemistry. Our model is able to address the integrated response of nitrogen fixation by Trichodesmium and Crocosphaera to warming under the IPCC high emission RCP8.5 scenario for the first time. Our results project a global decline in nitrogen fixation over the coming century. However, the regional response of nitrogen fixation to climate change is modulated by the diazotroph-specific thermal performance curves and EUE, particularly in the Pacific Ocean, which shapes global trends. Spatially, the response of both diazotrophs is similar with expansion towards higher latitudes and reduced rates of nitrogen fixation in the lower latitudes. Overall, 95%-97% of the nitrogen fixation climate signal can be attributed to the combined effect of temperature on the niche and physiology of marine diazotrophs, with decreases being associated with a reduced niche and increases resulting due to a combination of expanding niche and temperature driven changes to EUE. Climate change impacts on both the niche and physiology of marine diazotrophs interact to shape patterns of marine nitrogen fixation, which will have important implications for ocean productivity in the future.
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Affiliation(s)
- Lewis Wrightson
- Department of Earth, Ocean and Ecological SciencesUniversity of LiverpoolLiverpoolUK
| | - Nina Yang
- Department of Biological SciencesUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Claire Mahaffey
- Department of Earth, Ocean and Ecological SciencesUniversity of LiverpoolLiverpoolUK
| | - David A. Hutchins
- Department of Biological SciencesUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
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Aerosol Nutrients and Their Biological Influence on the Northwest Pacific Ocean (NWPO) and Its Marginal Seas. BIOLOGY 2022; 11:biology11060842. [PMID: 35741363 PMCID: PMC9219953 DOI: 10.3390/biology11060842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/22/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary With intensifying human activities in the past decades, East Asia has recorded increasingly severe air pollution and become the second largest aerosol source on earth. The large quantity of aerosol emissions is not only a major health threat to humans, but can also be transported for a long distance and deposited in downwind seas and oceans. The aerosol contains major ions, heavy metals, and organic matters that are important external nutrients in upper oceans and potentially influence marine microbes and biogeochemical cycles. Therefore, the role of atmospheric deposition to oceans has received growing attention in recent years. In this paper, the current state of knowledge on the atmospheric nutrients and the biological effect of East Asian aerosol deposition on the northwest Pacific Ocean are reviewed, which could help us better understand the comprehensive influence of East Asian aerosols on marine ecosystems, and give insights into future research directions, especially under the future scenarios of changing human activities and climate. Abstract Atmospheric deposition is recognized as a significant source of nutrients in the surface ocean. The East Asia region is among the largest sources of aerosol emissions in the world, due to its large industrial, agricultural, and energy production. Thus, East Asian aerosols contain a large proportion of anthropogenic particles that are characterized by small size, complex composition, and high nutrient dissolution, resulting in important influences on marine microbes and biogeochemical cycles in the downwind areas of the northwest Pacific Ocean (NWPO). By using remote sensing, modeling, and incubation experimental methods, enhanced primary production due to the East Asian aerosol input has been observed in the NWPO, with subsequent promotion and inhibition impacts on different phytoplankton taxa. Changes of bacterial activity and diversity also occur in response to aerosol input. The impact of East Asian aerosol loadings is closely related to the amount and composition of the aerosol deposition as well as the hydrological condition of the receiving seawater. Here, we review the current state of knowledge on the atmospheric nutrients and the effects of the East Asian aerosols on microbes in the NWPO region. Future research perspectives are also proposed.
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