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Uesaka K, Banba M, Chiba S, Fujita Y. Restoration of the Functional nif Gene Cluster by Complex Recombination Events during Heterocyst Development in the Nitrogen-Fixing Cyanobacterium Calothrix sp. NIES-4101. PLANT & CELL PHYSIOLOGY 2024; 65:1050-1064. [PMID: 38305573 PMCID: PMC11249958 DOI: 10.1093/pcp/pcae011] [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: 12/12/2023] [Revised: 01/17/2024] [Accepted: 02/01/2024] [Indexed: 02/03/2024]
Abstract
In the genome of the heterocystous cyanobacterium Calothrix sp. NIES-4101 (NIES-4101), the four genes essential for nitrogen fixation (nifB, nifH, nifD and nifK) are highly fragmented into 13 parts in a 350-kb chromosomal region, and four of these parts are encoded in the reverse strand. Such a complex fragmentation feature makes it difficult to restore the intact nifBHDK genes by the excision mechanism found in the nifD gene of the Anabaena sp. PCC 7120 heterocyst. To examine the nitrogen-fixing ability of NIES-4101, we confirmed that NIES-4101 grew well on a combined nitrogen-free medium and showed high nitrogenase activity, which strongly suggested that the complete nifBHDK genes are restored by a complex recombination process in heterocysts. Next, we resequenced the genome prepared from cells grown under nitrogen-fixing conditions. Two contigs covering the complete nifHDK and nifB genes were found by de novo assembly of the sequencing reads. In addition, the DNA fragments covering the nifBHDK operon were successfully amplified by PCR. We propose that the process of nifBHDK restoration occurs as follows. First, the nifD-nifK genes are restored by four excision events. Then, the complete nifH and nifB genes are restored by two excision events followed by two successive inversion events between the inverted repeat sequences and one excision event, forming the functional nif gene cluster, nifB-fdxN-nifS-nifU-nifH-nifD-nifK. All genes coding recombinases responsible for these nine recombination events are located close to the terminal repeat sequences. The restoration of the nifBHDK genes in NIES-4101 is the most complex genome reorganization reported in heterocystous cyanobacteria.
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Affiliation(s)
- Kazuma Uesaka
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
| | - Mari Banba
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
| | - Sotaro Chiba
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
| | - Yuichi Fujita
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
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Masuda T, Mareš J, Shiozaki T, Inomura K, Fujiwara A, Prášil O. Crocosphaera watsonii - A widespread nitrogen-fixing unicellular marine cyanobacterium. JOURNAL OF PHYCOLOGY 2024; 60:604-620. [PMID: 38551849 DOI: 10.1111/jpy.13450] [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: 05/05/2023] [Revised: 12/14/2023] [Accepted: 02/08/2024] [Indexed: 06/12/2024]
Abstract
Crocosphaera watsonii is a unicellular N2-fixing (diazotrophic) cyanobacterium observed in tropical and subtropical oligotrophic oceans. As a diazotroph, it can be a source of bioavailable nitrogen (N) to the microbial community in N-limited environments, and this may fuel primary production in the regions where it occurs. Crocosphaera watsonii has been the subject of intense study, both in culture and in field populations. Here, we summarize the current understanding of the phylogenetic and physiological diversity of C. watsonii, its distribution, and its ecological niche. Analysis of the relationships among the individual Crocosphaera species and related free-living and symbiotic lineages of diazotrophs based on the nifH gene have shown that the C. watsonii group holds a basal position and that its sequence is more similar to Rippkaea and Zehria than to other Crocosphaera species. This finding warrants further scrutiny to determine if the placement is related to a horizontal gene transfer event. Here, the nifH UCYN-B gene copy number from a recent synthesis effort was used as a proxy for relative C. watsonii abundance to examine patterns of C. watsonii distribution as a function of environmental factors, like iron and phosphorus concentration, and complimented with a synthesis of C. watsonii physiology. Furthermore, we have summarized the current knowledge of C. watsonii with regards to N2 fixation, photosynthesis, and quantitative modeling of physiology. Because N availability can limit primary production, C. watsonii is widely recognized for its importance to carbon and N cycling in ocean ecosystems, and we conclude this review by highlighting important topics for further research on this important species.
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Affiliation(s)
- Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
- Japan Fisheries Research and Education Agency, Shiogama, Miyagi, Japan
| | - Jan Mareš
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
- Institute of Hydrobiology, Biology Centre, The Czech Academy of Sciences, České Budejovice, Czech Republic
| | - Takuhei Shiozaki
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Amane Fujiwara
- Research Institute for Global Change, JAMSTEC, Yokosuka, Japan
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
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3
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Zhang H, Tan Y, Zhou Y, Liu J, Xia X. Light-dark fluctuated metabolic features of diazotrophic and non-diazotrophic cyanobacteria and their coexisting bacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 910:168702. [PMID: 37992836 DOI: 10.1016/j.scitotenv.2023.168702] [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: 09/06/2023] [Revised: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 11/24/2023]
Abstract
Cyanobacteria, the most abundant photosynthetic organisms in oceans, are tightly associated with diverse microbiota. However, the relationships between heterotrophic bacteria and cyanobacteria, particularly the diazotrophic group, are not fully understood. Here, we compared diel gene expressions of N2 fixing cyanobacteria Crocosphaera watsonii WH0003 and non-diazotrophic Synechococcus sp. RS9902 and their associated bacteria using metatranscriptomics approach. WH0003 showed significant up-regulation of O2 restriction and oxidative phosphorylation related genes at nighttime due to large carbon and energy investments for active N2 fixation. In contrast, RS9902 had higher expression for those genes at daytime. The two cyanobacteria hosted distinct bacterial communities with clear separate substrate utilization niches to reduce competition. Light-dark partitioning of nutrient acquisition among the dominant bacterial groups likely contributed to the dynamic balance for community coexistence. Moreover, particle-attached (PA) bacteria in RS9902 largely expressed glycoside hydrolases to hydrolyze complex carbohydrate compounds, while free-living (FL) bacteria priorly assimilated soluble, diffusible molecules. Spatial partitioning of nutrient acquisition between PA and FL bacteria implied that location initially influenced metabolic features of host associated bacteria. Our results advance knowledge on light-dark regulated metabolic activities of diazotrophic and non-diazotrophic cyanobacteria, and provide new insights into the coexisting strategies of different bacterial groups.
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Affiliation(s)
- Hao Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Yehui Tan
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Youping Zhou
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Jiaxing Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China..
| | - Xiaomin Xia
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China..
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Vieyra‐Mexicano C, Souza V, Pajares S. Distribution of the N 2 -fixing cyanobacterium Candidatus Atelocyanobacterium thalassa in the Mexican Pacific upwelling system under two contrasting El Niño Southern Oscillation conditions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13237. [PMID: 38350668 PMCID: PMC10866059 DOI: 10.1111/1758-2229.13237] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/19/2024] [Indexed: 02/15/2024]
Abstract
The unicellular cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is a key diazotroph in the global ocean owing to its high N2 fixation rates and wide distribution in marine environments. Nevertheless, little is known about UCYN-A in oxygen-deficient zones (ODZs), which may be optimal environments for marine diazotrophy. Therefore, the distribution and diversity of UCYN-A were studied in two consecutive years under contrasting phases (La Niña vs. El Niño) of El Niño Southern Oscillation (ENSO) along a transect in the ODZ of the Mexican Pacific upwelling system. Of the three UCYN-A sublineages found, UCYN-A1 and UCYN-A3 were barely detected, whereas UCYN-A2 was dominant in all the stations and showed a wide distribution in both ENSO phases. The presence of UCYN-A was associated with well-oxygenated waters, but it was also found for the first time under suboxic conditions (<20 μM) at the bottom of a shallow coastal station, within the oxygen-poor and nutrient-rich Subsurface Subtropical water mass. This study contributes to the understanding of UCYN-A distribution under different oceanographic conditions associated with ENSO phases in upwelling systems, especially because of the current climate change and increasing deoxygenation in many areas of the world's oceans.
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Affiliation(s)
- Cinthya Vieyra‐Mexicano
- Unidad Académica de Ecología y Biodiversidad Acuática, Institute of Marine Sciences and LimnologyNational Autonomous University of MexicoMexico CityMexico
- Posgrado en Ciencias del Mar y LimnologíaNational Autonomous University of MexicoMexico CityMexico
| | - Valeria Souza
- Departamento de Ecología Evolutiva, Institute of EcologyNational Autonomous University of MexicoMexico CityMexico
| | - Silvia Pajares
- Unidad Académica de Ecología y Biodiversidad Acuática, Institute of Marine Sciences and LimnologyNational Autonomous University of MexicoMexico CityMexico
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Jabir T, Jain A, Vipindas PV, Krishnan KP. Stochastic Processes Dominate in the Water Mass-Based Segregation of Diazotrophs in a High Arctic Fjord (Svalbard). MICROBIAL ECOLOGY 2023; 86:2733-2746. [PMID: 37532947 DOI: 10.1007/s00248-023-02276-w] [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: 03/01/2023] [Accepted: 07/24/2023] [Indexed: 08/04/2023]
Abstract
Nitrogen-fixing or diazotrophic microbes fix atmospheric nitrogen (N2) to ammonia (NH3+) using nitrogenase enzyme and play a crucial role in regulating marine primary productivity and carbon dioxide sequestration. However, there is a lack of information about the diversity, structure, and environmental regulations of the diazotrophic communities in the high Arctic fjords, such as Kongsfjorden. Here, we employed nifH gene sequencing to clarify variations in composition, community structure, and assembly mechanism among the diazotrophs of the salinity-driven stratified waters of Kongsfjorden. The principal environmental and ecological drivers of the observed variations were identified. The majority of the nifH gene sequences obtained in the present study belonged to cluster I and cluster III nifH phylotypes, accounting for 65% and 25% of the total nifH gene sequences. The nifH gene diversity and composition, irrespective of the size fractions (free-living and particle attached), showed a clear separation among water mass types, i.e., Atlantic-influenced versus glacier-influenced water mass. Higher nifH gene diversity and relative abundances of non-cyanobacterial nifH OTUs, affiliated with uncultured Rhizobiales, Burkholderiales, Alteromonadaceae, Gallionellaceae (cluster I) and uncultured Deltaproteobacteria including Desulfuromonadaceae (cluster III), were prevalent in GIW while uncultured Gammaproteobacteria and Desulfobulbaceae were abundant in AIW. The diazotrophic community assembly was dominated by stochastic processes, principally ecological drift, and to lesser degrees dispersal limitation and homogeneous dispersal. Differences in the salinity and dissolved oxygen content lead to the vertical segregation of diazotrophs among water mass types. These findings suggest that water column stratification affects the composition and assembly mechanism of diazotrophic communities and thus could affect nitrogen fixation in the Arctic fjord.
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Affiliation(s)
- Thajudeen Jabir
- Arctic Ecology and Biogeochemistry, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama, Goa, 403 804, India.
| | - Anand Jain
- Arctic Ecology and Biogeochemistry, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama, Goa, 403 804, India
| | - Puthiya Veettil Vipindas
- Arctic Ecology and Biogeochemistry, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama, Goa, 403 804, India
| | - Kottekkatu Padinchati Krishnan
- Arctic Ecology and Biogeochemistry, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama, Goa, 403 804, India
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Mandhata CP, Bishoyi AK, Sahoo CR, Maharana S, Padhy RN. Insight to biotechnological utility of phycochemicals from cyanobacterium Anabaena sp.: An overview. Fitoterapia 2023; 169:105594. [PMID: 37343687 DOI: 10.1016/j.fitote.2023.105594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/12/2023] [Accepted: 06/17/2023] [Indexed: 06/23/2023]
Abstract
Cyanobacteria (blue-green algae) are well-known for the ability to excrete extra-cellular products, as a variety of cyanochemicals (phycocompounds) of curio with several extensive therapeutic applications. Among these phycocompound, the cyanotoxins from certain water-bloom forming taxa are toxic to biota, including crocodiles. Failure of current non-renewable source compounds in producing sustainable and non-toxic therapeutics led the urgency of discovering products from natural sources. Particularly, compounds of the filamentous N2-fixing Anabaena sp. have effective antibacterial, antifungal, antioxidant, and anticancer properties. Today, such newer compounds are the potential targets for the possible novel chemical scaffolds, suitable for mainstream-drug development cascades. Bioactive compounds of Anabaena sp. such as, anatoxins, hassallidins and phycobiliproteins have proven their inherent antibacterial, antifungal, and antineoplastic activities, respectively. Herein, the available details of the biomass production and the inherent phyco-constituents namely, alkaloids, lipids, phenols, peptides, proteins, polysaccharides, terpenoids and cyanotoxins are considered, along with geographical distributions and morphological characteristics of the cyanobacterium. The acquisitions of cyanochemicals in recent years have newly addressed several pharmaceutical aliments, and the understanding of the associated molecular interactions of phycochemicals have been considered, for plausible use in drug developments in future.
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Affiliation(s)
- Chinmayee Priyadarsani Mandhata
- Central Research Laboratory, Institute of Medical Science & SUM Hospital, Siksha O Anusandhan Deemed to be University, Bhubaneswar, 751003, Odisha, India
| | - Ajit Kumar Bishoyi
- Central Research Laboratory, Institute of Medical Science & SUM Hospital, Siksha O Anusandhan Deemed to be University, Bhubaneswar, 751003, Odisha, India
| | - Chita Ranjan Sahoo
- Central Research Laboratory, Institute of Medical Science & SUM Hospital, Siksha O Anusandhan Deemed to be University, Bhubaneswar, 751003, Odisha, India.
| | | | - Rabindra Nath Padhy
- Central Research Laboratory, Institute of Medical Science & SUM Hospital, Siksha O Anusandhan Deemed to be University, Bhubaneswar, 751003, Odisha, India.
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7
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Masuda T, Bečková M, Turóczy Z, Pilný J, Sobotka R, Trinugroho JP, Nixon PJ, Prášil O, Komenda J. Accumulation of Cyanobacterial Photosystem II Containing the 'Rogue' D1 Subunit Is Controlled by FtsH Protease and Synthesis of the Standard D1 Protein. PLANT & CELL PHYSIOLOGY 2023; 64:660-673. [PMID: 36976618 DOI: 10.1093/pcp/pcad027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 06/16/2023]
Abstract
Unicellular diazotrophic cyanobacteria contribute significantly to the photosynthetic productivity of the ocean and the fixation of molecular nitrogen, with photosynthesis occurring during the day and nitrogen fixation during the night. In species like Crocosphaera watsonii WH8501, the decline in photosynthetic activity in the night is accompanied by the disassembly of oxygen-evolving photosystem II (PSII) complexes. Moreover, in the second half of the night phase, a small amount of rogue D1 (rD1), which is related to the standard form of the D1 subunit found in oxygen-evolving PSII, but of unknown function, accumulates but is quickly degraded at the start of the light phase. We show here that the removal of rD1 is independent of the rD1 transcript level, thylakoid redox state and trans-thylakoid pH but requires light and active protein synthesis. We also found that the maximal level of rD1 positively correlates with the maximal level of chlorophyll (Chl) biosynthesis precursors and enzymes, which suggests a possible role for rogue PSII (rPSII) in the activation of Chl biosynthesis just before or upon the onset of light, when new photosystems are synthesized. By studying strains of Synechocystis PCC 6803 expressing Crocosphaera rD1, we found that the accumulation of rD1 is controlled by the light-dependent synthesis of the standard D1 protein, which triggers the fast FtsH2-dependent degradation of rD1. Affinity purification of FLAG-tagged rD1 unequivocally demonstrated the incorporation of rD1 into a non-oxygen-evolving PSII complex, which we term rPSII. The complex lacks the extrinsic proteins stabilizing the oxygen-evolving Mn4CaO5 cluster but contains the Psb27 and Psb28-1 assembly factors.
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Affiliation(s)
- Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Martina Bečková
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Zoltán Turóczy
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Jan Pilný
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice 370 05, Czech Republic
| | - Joko P Trinugroho
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Josef Komenda
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice 370 05, Czech Republic
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Alleman AB, Peters JW. Mechanisms for Generating Low Potential Electrons across the Metabolic Diversity of Nitrogen-Fixing Bacteria. Appl Environ Microbiol 2023; 89:e0037823. [PMID: 37154716 PMCID: PMC10231201 DOI: 10.1128/aem.00378-23] [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] [Indexed: 05/10/2023] Open
Abstract
The availability of fixed nitrogen is a limiting factor in the net primary production of all ecosystems. Diazotrophs overcome this limit through the conversion of atmospheric dinitrogen to ammonia. Diazotrophs are phylogenetically diverse bacteria and archaea that exhibit a wide range of lifestyles and metabolisms, including obligate anaerobes and aerobes that generate energy through heterotrophic or autotrophic metabolisms. Despite the diversity of metabolisms, all diazotrophs use the same enzyme, nitrogenase, to reduce N2. Nitrogenase is an O2-sensitive enzyme that requires a high amount of energy in the form of ATP and low potential electrons carried by ferredoxin (Fd) or flavodoxin (Fld). This review summarizes how the diverse metabolisms of diazotrophs utilize different enzymes to generate low potential reducing equivalents for nitrogenase catalysis. These enzymes include substrate-level Fd oxidoreductases, hydrogenases, photosystem I or other light-driven reaction centers, electron bifurcating Fix complexes, proton motive force-driven Rnf complexes, and Fd:NAD(P)H oxidoreductases. Each of these enzymes is critical for generating low potential electrons while simultaneously integrating the native metabolism to balance nitrogenase's overall energy needs. Understanding the diversity of electron transport systems to nitrogenase in various diazotrophs will be essential to guide future engineering strategies aimed at expanding the contributions of biological nitrogen fixation in agriculture.
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Affiliation(s)
- Alexander B. Alleman
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - John W. Peters
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
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Investigating the Unique Ability of Trichodesmium To Fix Carbon and Nitrogen Simultaneously Using MiMoSA. mSystems 2023; 8:e0060120. [PMID: 36598239 PMCID: PMC9948733 DOI: 10.1128/msystems.00601-20] [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] [Indexed: 01/05/2023] Open
Abstract
The open ocean is an extremely competitive environment, partially due to the dearth of nutrients. Trichodesmium erythraeum, a marine diazotrophic cyanobacterium, is a keystone species in the ocean due to its ability to fix nitrogen and leak 30 to 50% into the surrounding environment, providing a valuable source of a necessary macronutrient to other species. While there are other diazotrophic cyanobacteria that play an important role in the marine nitrogen cycle, Trichodesmium is unique in its ability to fix both carbon and nitrogen simultaneously during the day without the use of specialized cells called heterocysts to protect nitrogenase from oxygen. Here, we use the advanced modeling framework called multiscale multiobjective systems analysis (MiMoSA) to investigate how Trichodesmium erythraeum can reduce dimolecular nitrogen to ammonium in the presence of oxygen. Our simulations indicate that nitrogenase inhibition is best modeled as Michealis-Menten competitive inhibition and that cells along the filament maintain microaerobia using high flux through Mehler reactions in order to protect nitrogenase from oxygen. We also examined the effect of location on metabolic flux and found that cells at the end of filaments operate in distinctly different metabolic modes than internal cells despite both operating in a photoautotrophic mode. These results give us important insight into how this species is able to operate photosynthesis and nitrogen fixation simultaneously, giving it a distinct advantage over other diazotrophic cyanobacteria because they can harvest light directly to fuel the energy demand of nitrogen fixation. IMPORTANCE Trichodesmium erythraeum is a marine cyanobacterium responsible for approximately half of all biologically fixed nitrogen, making it an integral part of the global nitrogen cycle. Interestingly, unlike other nitrogen-fixing cyanobacteria, Trichodesmium does not use temporal or spatial separation to protect nitrogenase from oxygen poisoning; instead, it operates photosynthesis and nitrogen fixation reactions simultaneously during the day. Unfortunately, the exact mechanism the cells utilize to operate carbon and nitrogen fixation simultaneously is unknown. Here, we use an advanced metabolic modeling framework to investigate and identify the most likely mechanisms Trichodesmium uses to protect nitrogenase from oxygen. The model predicts that cells operate in a microaerobic mode, using both respiratory and Mehler reactions to dramatically reduce intracellular oxygen concentrations.
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10
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Dal Co A, Ackermann M, van Vliet S. Spatial self-organization of metabolism in microbial systems: A matter of enzymes and chemicals. Cell Syst 2023; 14:98-108. [PMID: 36796335 DOI: 10.1016/j.cels.2022.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/14/2022] [Accepted: 12/21/2022] [Indexed: 02/17/2023]
Abstract
Most bacteria live in dense, spatially structured communities such as biofilms. The high density allows cells to alter the local microenvironment, whereas the limited mobility can cause species to become spatially organized. Together, these factors can spatially organize metabolic processes within microbial communities so that cells in different locations perform different metabolic reactions. The overall metabolic activity of a community depends both on how metabolic reactions are arranged in space and on how they are coupled, i.e., how cells in different regions exchange metabolites. Here, we review mechanisms that lead to the spatial organization of metabolic processes in microbial systems. We discuss factors that determine the length scales over which metabolic activities are arranged in space and highlight how the spatial organization of metabolic processes affects the ecology and evolution of microbial communities. Finally, we define key open questions that we believe should be the main focus of future research.
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Affiliation(s)
- Alma Dal Co
- Department of Computational Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Martin Ackermann
- Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Microbiology, Eawag, 8600 Duebendorf, Switzerland.
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11
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Campbell MA, Bauersachs T, Schwark L, Proemse BC, Eberhard RS, Coolen MJL, Grice K. Salinity-driven ecology and diversity changes of heterocytous cyanobacteria in Australian freshwater and coastal-marine microbial mats. Environ Microbiol 2022; 24:6493-6509. [PMID: 36156347 PMCID: PMC10092834 DOI: 10.1111/1462-2920.16225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 09/23/2022] [Indexed: 01/12/2023]
Abstract
N2 -fixing heterocytous cyanobacteria are considered to play a minor role in sustaining coastal microbial mat communities developing under normal marine to hypersaline conditions. Here, we investigated microbial mats growing under different salinities from freshwater mats of Giblin River (Tasmania) to metahaline and hypersaline mats of Shark Bay (Western Australia). Analyses of genetic (rRNA and mRNA) and biological markers (heterocyte glycolipids) revealed an unexpectedly large diversity of heterocytous cyanobacteria in all the studied microbial mat communities. It was observed that the taxonomic distribution as well as abundance of cyanobacteria is strongly affected by salinity. Low salinity favoured the presence of heterocytous cyanobacteria in freshwater mats, while mats thriving in higher salinities mainly supported the growth unicellular and filamentous non-heterocytous genera. However, even though mRNA transcripts derived from heterocytous cyanobacteria were lower in Shark Bay (<6%) microbial mats, functional analyses revealed that these diazotrophs were transcribing a substantial proportion of the genes involved in biofilm formation and nitrogen fixation. Overall, our data reveal an unexpectedly high diversity of heterocytous cyanobacteria (e.g. Calothrix, Scytonema, Nodularia, Gloeotrichia, Stigonema, Fischerella and Chlorogloeopsis) that had yet to be described in metahaline and hypersaline microbial mats from Shark Bay and that they play a vital role in sustaining the ecosystem functioning of coastal-marine microbial mat systems.
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Affiliation(s)
- Matthew A Campbell
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Thorsten Bauersachs
- Institute of Geosciences, Organic Geochemistry Group, Christian-Albrechts-University, Kiel, Germany
| | - Lorenz Schwark
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia.,Institute of Geosciences, Organic Geochemistry Group, Christian-Albrechts-University, Kiel, Germany
| | - Bernadette C Proemse
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
| | - Rolan S Eberhard
- Natural and Cultural Heritage Division, Department of Primary Industries Parks, Water and Environment, Hobart, Tasmania, Australia
| | - Marco J L Coolen
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Kliti Grice
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
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12
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Masuda T, Inomura K, Gao M, Armin G, Kotabová E, Bernát G, Lawrenz-Kendrick E, Lukeš M, Bečková M, Steinbach G, Komenda J, Prášil O. The balance between photosynthesis and respiration explains the niche differentiation between Crocosphaera and Cyanothece. Comput Struct Biotechnol J 2022; 21:58-65. [PMID: 36514336 PMCID: PMC9732122 DOI: 10.1016/j.csbj.2022.11.029] [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: 10/14/2022] [Revised: 11/12/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022] Open
Abstract
Crocosphaera and Cyanothece are both unicellular, nitrogen-fixing cyanobacteria that prefer different environments. Whereas Crocosphaera mainly lives in nutrient-deplete, open oceans, Cyanothece is more common in coastal, nutrient-rich regions. Despite their physiological similarities, the factors separating their niches remain elusive. Here we performed physiological experiments on clone cultures and expand upon a simple ecological model to show that their different niches can be sufficiently explained by the observed differences in their photosynthetic capacities and rates of carbon (C) consumption. Our experiments revealed that Cyanothece has overall higher photosynthesis and respiration rates than Crocosphaera. A simple growth model of these microorganisms suggests that C storage and consumption are previously under-appreciated factors when evaluating the occupation of niches by different marine nitrogen fixers.
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Affiliation(s)
- Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Corresponding authors.
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Meng Gao
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Eva Kotabová
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Gábor Bernát
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Tihany, Hungary
| | - Evelyn Lawrenz-Kendrick
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Martin Lukeš
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Martina Bečková
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Gábor Steinbach
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Cellular Imaging Laboratory, Biological Research Center, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Josef Komenda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Corresponding authors.
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13
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Virtual 2D map of cyanobacterial proteomes. PLoS One 2022; 17:e0275148. [PMID: 36190972 PMCID: PMC9529120 DOI: 10.1371/journal.pone.0275148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/12/2022] [Indexed: 11/05/2022] Open
Abstract
Cyanobacteria are prokaryotic Gram-negative organisms prevalent in nearly all habitats. A detailed proteomics study of Cyanobacteria has not been conducted despite extensive study of their genome sequences. Therefore, we conducted a proteome-wide analysis of the Cyanobacteria proteome and found Calothrix desertica as the largest (680331.825 kDa) and Candidatus synechococcus spongiarum as the smallest (42726.77 kDa) proteome of the cyanobacterial kingdom. A Cyanobacterial proteome encodes 312.018 amino acids per protein, with a molecular weight of 182173.1324 kDa per proteome. The isoelectric point (pI) of the Cyanobacterial proteome ranges from 2.13 to 13.32. It was found that the Cyanobacterial proteome encodes a greater number of acidic-pI proteins, and their average pI is 6.437. The proteins with higher pI are likely to contain repetitive amino acids. A virtual 2D map of Cyanobacterial proteome showed a bimodal distribution of molecular weight and pI. Several proteins within the Cyanobacterial proteome were found to encode Selenocysteine (Sec) amino acid, while Pyrrolysine amino acids were not detected. The study can enable us to generate a high-resolution cell map to monitor proteomic dynamics. Through this computational analysis, we can gain a better understanding of the bias in codon usage by analyzing the amino acid composition of the Cyanobacterial proteome.
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14
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Chen M, Teng W, Zhao L, Han B, Song L, Shu W. Phylogenomics uncovers evolutionary trajectory of nitrogen fixation in Cyanobacteria. Mol Biol Evol 2022; 39:6659242. [PMID: 35946347 PMCID: PMC9435057 DOI: 10.1093/molbev/msac171] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Biological nitrogen fixation (BNF) by cyanobacteria is of significant importance for the Earth’s biogeochemical nitrogen cycle but is restricted to a few genera that do not form monophyletic group. To explore the evolutionary trajectory of BNF and investigate the driving forces of its evolution, we analyze 650 cyanobacterial genomes and compile the database of diazotrophic cyanobacteria based on the presence of nitrogen fixation gene clusters (NFGCs). We report that 266 of 650 examined genomes are NFGC-carrying members, and these potentially diazotrophic cyanobacteria are unevenly distributed across the phylogeny of Cyanobacteria, that multiple independent losses shaped the scattered distribution. Among the diazotrophic cyanobacteria, two types of NFGC exist, with one being ancestral and abundant, which have descended from diazotrophic ancestors, and the other being anaerobe-like and sparse, possibly being acquired from anaerobic microbes through horizontal gene transfer. Interestingly, we illustrate that the origin of BNF in Cyanobacteria coincide with two major evolutionary events. One is the origin of multicellularity of cyanobacteria, and the other is concurrent genetic innovations with massive gene gains and expansions, implicating their key roles in triggering the evolutionary transition from nondiazotrophic to diazotrophic cyanobacteria. Additionally, we reveal that genes involved in accelerating respiratory electron transport (coxABC), anoxygenic photosynthetic electron transport (sqr), as well as anaerobic metabolisms (pfor, hemN, nrdG, adhE) are enriched in diazotrophic cyanobacteria, representing adaptive genetic signatures that underpin the diazotrophic lifestyle. Collectively, our study suggests that multicellularity, together with concurrent genetic adaptations contribute to the evolution of diazotrophic cyanobacteria.
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Affiliation(s)
- Mengyun Chen
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
| | - Wenkai Teng
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, PR China
| | - Liang Zhao
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
| | - Boping Han
- Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou 510632, PR China
| | - Lirong Song
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Hubei 430072, PR China
| | - Wensheng Shu
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
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15
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Srisawat P, Higuchi-Takeuchi M, Numata K. Microbial autotrophic biorefineries: Perspectives for biopolymer production. Polym J 2022. [DOI: 10.1038/s41428-022-00675-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
AbstractThe use of autotrophic microorganisms to fabricate biochemical products has attracted much attention in both academia and industry. Unlike heterotrophic microorganisms that require carbohydrates and amino acids for growth, autotrophic microorganisms have evolved to utilize either light (photoautotrophs) or chemical compounds (chemolithotrophs) to fix carbon dioxide (CO2) and drive metabolic processes. Several biotechnological approaches, including synthetic biology and metabolic engineering, have been proposed to harness autotrophic microorganisms as a sustainable/green production platform for commercially essential products such as biofuels, commodity chemicals, and biopolymers. Here, we review the recent advances in natural autotrophic microorganisms (photoautotrophic and chemoautotrophic), focusing on the biopolymer production. We present current state-of-the-art technologies to engineer autotrophic microbial cell factories for efficient biopolymer production.
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16
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Yu X, Chen J, Gutang Q, Sanganyado E, Bi R, Liu W. Biogeographic patterns of benthic microbial communities in metal(loid)-contaminated semi-enclosed bay. CHEMOSPHERE 2022; 299:134412. [PMID: 35367498 DOI: 10.1016/j.chemosphere.2022.134412] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
Anthropogenic activities can adversely impact biogeochemical processes essential for maintaining ecosystem health in semi-enclosed bays. However, the influence of anthropogenic contaminants such as potentially toxic elements on microbial communities that regulate biogeochemical cycles in semi-enclosed bays is poorly understood. We determined the concentrations of four potentially toxic elements (Cu, Zn, Pb, and As) in sediments from a typical tropical semi-enclosed bay in Guangdong, China. Source apportionment using Pearson's correlation analysis revealed that aquaculture activities were probably the primary source of Cu, Zn, and Pb. Using high-throughput sediment DNA sequencing, we found that Proteobacteria was the dominant phylum in sediments. There was no evidence suggesting site-specific variation in microbial function even though sediments adjacent to aquaculture discharge points had higher microbial diversity. In contrast, pollutant-specific variations were observed; for example, Zn and Pd showed potential adverse effects on the environmental information processing function, while As showed a negative correlation with metabolic function. Based on different environmental characteristics, future research should consider the impact of multiple factors on the bacterial community in aquaculture systems.
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Affiliation(s)
- Xiaoxuan Yu
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China
| | - Jinjin Chen
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China
| | - Qilin Gutang
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China
| | - Edmond Sanganyado
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China.
| | - Ran Bi
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China
| | - Wenhua Liu
- Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Science, Shantou University, Shantou, Guangdong, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China.
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17
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Limnospira fusiformis harbors dinitrogenase reductase (nifH)-like genes, but does not show N2 fixation activity. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Mukherjee M, Geeta A, Ghosh S, Prusty A, Dutta S, Sarangi AN, Behera S, Adhikary SP, Tripathy S. Genome Analysis Coupled With Transcriptomics Reveals the Reduced Fitness of a Hot Spring Cyanobacterium Mastigocladus laminosus UU774 Under Exogenous Nitrogen Supplement. Front Microbiol 2022; 13:909289. [PMID: 35847102 PMCID: PMC9284123 DOI: 10.3389/fmicb.2022.909289] [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: 03/31/2022] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
The present study focuses on the stress response of a filamentous, AT-rich, heterocystous cyanobacterium Mastigocladus laminosus UU774, isolated from a hot spring, Taptapani, located in the eastern part of India. The genome of UU774 contains an indispensable fragment, scaffold_38, of unknown origin that is implicated during severe nitrogen and nutrition stress. Prolonged exposure to nitrogen compounds during starvation has profound adverse effects on UU774, leading to loss of mobility, loss of ability to fight pathogens, reduced cell division, decreased nitrogen-fixing ability, reduced ability to form biofilms, reduced photosynthetic and light-sensing ability, and reduced production of secreted effectors and chromosomal toxin genes, among others. Among genes showing extreme downregulation when grown in a medium supplemented with nitrogen with the fold change > 5 are transcriptional regulator gene WalR, carbonic anhydrases, RNA Polymerase Sigma F factor, fimbrial protein, and twitching mobility protein. The reduced expression of key enzymes involved in the uptake of phosphate and enzymes protecting oxygen-sensitive nitrogenases is significant during the presence of nitrogen. UU774 is presumed to withstand heat by overexpressing peptidases that may be degrading abnormally folded proteins produced during heat. The absence of a key gene responsible for heterocyst pattern formation, patS, and an aberrant hetN without a functional motif probably lead to the formation of a chaotic heterocyst pattern in UU774. We suggest that UU774 has diverged from Fischerella sp. PCC 9339, another hot spring species isolated in the United States.
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Affiliation(s)
- Mayuri Mukherjee
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Aribam Geeta
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Samrat Ghosh
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Asharani Prusty
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Subhajeet Dutta
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Aditya Narayan Sarangi
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
| | - Smrutisanjita Behera
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
| | | | - Sucheta Tripathy
- Computational Genomics Lab, Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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19
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Heller P. Diel gene expression improves software prediction of cyanobacterial operons. PeerJ 2022; 10:e13259. [PMID: 35433132 PMCID: PMC9009326 DOI: 10.7717/peerj.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/22/2022] [Indexed: 01/13/2023] Open
Abstract
Cyanobacteria are important participants in global biogeochemical process, but their metabolic processes and genomic functions are incompletely understood. In particular, operon structure, which can provide valuable metabolic and genomic insight, is difficult to determine experimentally, and algorithmic operon predictions probably underestimate actual operon extent. A software method is presented for enhancing current operon predictions by incorporating information from whole-genome time-series expression studies, using a Machine Learning classifier. Results are presented for the marine cyanobacterium Crocosphaera watsonii. A total of 15 operon enhancements are proposed. The source code is publicly available.
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20
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Garg R, Perez R, Maldener I. Analysis of Heterocyst and Akinete Specific Glycolipids in Cyanobacteria Using Thin-layer Chromatography. Bio Protoc 2022; 12:e4355. [PMID: 35434192 PMCID: PMC8983158 DOI: 10.21769/bioprotoc.4355] [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: 01/25/2022] [Revised: 11/17/2021] [Accepted: 02/03/2022] [Indexed: 12/29/2022] Open
Abstract
Several filamentous cyanobacteria like Nostoc differentiate specialized cells in response to changes in environmental factors, such as low light or nutrient starvation. These specialized cells are termed heterocysts and akinetes. Under conditions of nitrogen limitation, nitrogen-fixing heterocysts form in a semi-regular pattern and provide the filament with organic nitrogen compounds. Akinetes are spore-like dormant cells, which allow survival during adverse unfavorable conditions. Both cell types possess multilayered thick envelopes mainly composed of an outermost polysaccharide layer and inner layers of glycolipids, that are important for stress adaptation. To study these envelope glycolipids, a method for the isolation, separation and analysis of lipids from heterocysts and akinetes is essential. The present protocol describes a method involving the extraction of lipids from cyanobacteria using solvents and their separation and visualization on silica plates, to render analysis simple and easy. This protocol is relevant for studying mutants that are defective in glycolipid layer formation and for the comparison of glycolipid composition of heterocysts and akinetes under different environmental stresses.
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Affiliation(s)
- Ritu Garg
- Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Tübingen, Germany
| | - Rebeca Perez
- Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Tübingen, Germany
| | - Iris Maldener
- Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Tübingen, Germany; ,
*For correspondence:
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21
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Sharon I, Grogg M, Hilvert D, Schmeing TM. Structure and Function of the β-Asp-Arg Polymerase Cyanophycin Synthetase 2. ACS Chem Biol 2022; 17:670-679. [PMID: 35179888 DOI: 10.1021/acschembio.1c01007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyanophycin is a biopolymer composed of long chains of β-Asp-Arg. It is widespread in nature, being synthesized by many clades of bacteria, which use it as a cellular reservoir of nitrogen, carbon, and energy. Two enzymes are known to produce cyanophycin: cyanophycin synthetase 1 (CphA1), which builds cyanophycin from the amino acids Asp and Arg by alternating between two separate reactions for backbone extension and side chain modification, and cyanophycin synthetase 2 (CphA2), which polymerizes β-Asp-Arg dipeptides. CphA2 is evolutionarily related to CphA1, but questions about CphA2's altered structure and function remain unresolved. Cyanophycin and related molecules have drawn interest as green biopolymers. Because it only has a single active site, CphA2 could be more useful than CphA1 for biotechnological applications seeking to produce modified cyanophycin. In this study, we report biochemical assays on nine cyanobacterial CphA2 enzymes and report the crystal structure of CphA2 from Gloeothece citriformis at 3.0 Å resolution. The structure reveals a homodimeric, three-domain architecture. One domain harbors the polymerization active site and the two other domains have structural roles. The structure and biochemical assays explain how CphA2 binds and polymerizes β-Asp-Arg and highlights differences in in vitro oligomerization and activity between CphA2 enzymes. Using the structure and distinct activity profile as a guide, we introduced a single point mutation that converted Gloeothece citriformis CphA2 from a primer-dependent enzyme into a primer-independent enzyme.
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Affiliation(s)
- Itai Sharon
- Department of Biochemistry and Centre de recherche en biologie structurale, McGill University, Montréal H3G 0B1, Quebec, Canada
| | - Marcel Grogg
- Laboratory of Organic Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - T. Martin Schmeing
- Department of Biochemistry and Centre de recherche en biologie structurale, McGill University, Montréal H3G 0B1, Quebec, Canada
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22
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Defining the
Sphagnum
Core Microbiome across the North American Continent Reveals a Central Role for Diazotrophic Methanotrophs in the Nitrogen and Carbon Cycles of Boreal Peatland Ecosystems. mBio 2022. [PMCID: PMC8863050 DOI: 10.1128/mbio.03714-21] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peat mosses of the genus Sphagnum are ecosystem engineers that frequently predominate over photosynthetic production in boreal peatlands. Sphagnum spp. host diverse microbial communities capable of nitrogen fixation (diazotrophy) and methane oxidation (methanotrophy), thereby potentially supporting plant growth under severely nutrient-limited conditions. Moreover, diazotrophic methanotrophs represent a possible “missing link” between the carbon and nitrogen cycles, but the functional contributions of the Sphagnum-associated microbiome remain in question. A combination of metagenomics, metatranscriptomics, and dual-isotope incorporation assays was applied to investigate Sphagnum microbiome community composition across the North American continent and provide empirical evidence for diazotrophic methanotrophy in Sphagnum-dominated ecosystems. Remarkably consistent prokaryotic communities were detected in over 250 Sphagnum SSU rRNA libraries from peatlands across the United States (5 states, 17 bog/fen sites, 18 Sphagnum species), with 12 genera of the core microbiome comprising 60% of the relative microbial abundance. Additionally, nitrogenase (nifH) and SSU rRNA gene amplicon analysis revealed that nitrogen-fixing populations made up nearly 15% of the prokaryotic communities, predominated by Nostocales cyanobacteria and Rhizobiales methanotrophs. While cyanobacteria comprised the vast majority (>95%) of diazotrophs detected in amplicon and metagenome analyses, obligate methanotrophs of the genus Methyloferula (order Rhizobiales) accounted for one-quarter of transcribed nifH genes. Furthermore, in dual-isotope tracer experiments, members of the Rhizobiales showed substantial incorporation of 13CH4 and 15N2 isotopes into their rRNA. Our study characterizes the core Sphagnum microbiome across large spatial scales and indicates that diazotrophic methanotrophs, here defined as obligate methanotrophs of the rare biosphere (Methyloferula spp. of the Rhizobiales) that also carry out diazotrophy, play a keystone role in coupling of the carbon and nitrogen cycles in nutrient-poor peatlands.
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23
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Sharon I, Haque AS, Grogg M, Lahiri I, Seebach D, Leschziner AE, Hilvert D, Schmeing TM. Structures and function of the amino acid polymerase cyanophycin synthetase. Nat Chem Biol 2021; 17:1101-1110. [PMID: 34385683 DOI: 10.1038/s41589-021-00854-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 07/08/2021] [Indexed: 12/13/2022]
Abstract
Cyanophycin is a natural biopolymer produced by a wide range of bacteria, consisting of a chain of poly-L-Asp residues with L-Arg residues attached to the β-carboxylate sidechains by isopeptide bonds. Cyanophycin is synthesized from ATP, aspartic acid and arginine by a homooligomeric enzyme called cyanophycin synthetase (CphA1). CphA1 has domains that are homologous to glutathione synthetases and muramyl ligases, but no other structural information has been available. Here, we present cryo-electron microscopy and X-ray crystallography structures of cyanophycin synthetases from three different bacteria, including cocomplex structures of CphA1 with ATP and cyanophycin polymer analogs at 2.6 Å resolution. These structures reveal two distinct tetrameric architectures, show the configuration of active sites and polymer-binding regions, indicate dynamic conformational changes and afford insight into catalytic mechanism. Accompanying biochemical interrogation of substrate binding sites, catalytic centers and oligomerization interfaces combine with the structures to provide a holistic understanding of cyanophycin biosynthesis.
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Affiliation(s)
- Itai Sharon
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Quebec, Canada
| | - Asfarul S Haque
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Quebec, Canada
| | - Marcel Grogg
- Laboratory of Organic Chemistry, ETH Zürich, Zürich, Switzerland
| | - Indrajit Lahiri
- Department of Cellular and Molecular Medicine, and Section of Molecular Biology, Division of Biological Sciences, University of California San Diego (UCSD), La Jolla, CA, USA
| | - Dieter Seebach
- Laboratory of Organic Chemistry, ETH Zürich, Zürich, Switzerland
| | - Andres E Leschziner
- Department of Cellular and Molecular Medicine, and Section of Molecular Biology, Division of Biological Sciences, University of California San Diego (UCSD), La Jolla, CA, USA
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zürich, Zürich, Switzerland
| | - T Martin Schmeing
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Quebec, Canada.
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24
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Chakraborty S, Andersen KH, Visser AW, Inomura K, Follows MJ, Riemann L. Quantifying nitrogen fixation by heterotrophic bacteria in sinking marine particles. Nat Commun 2021; 12:4085. [PMID: 34215729 PMCID: PMC8253789 DOI: 10.1038/s41467-021-23875-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 05/21/2021] [Indexed: 02/06/2023] Open
Abstract
Nitrogen ([Formula: see text]) fixation by heterotrophic bacteria associated with sinking particles contributes to marine N cycling, but a mechanistic understanding of its regulation and significance are not available. Here we develop a mathematical model for unicellular heterotrophic bacteria growing on sinking marine particles. These bacteria can fix [Formula: see text] under suitable environmental conditions. We find that the interactive effects of polysaccharide and polypeptide concentrations, sinking speed of particles, and surrounding [Formula: see text] and [Formula: see text] concentrations determine the [Formula: see text] fixation rate inside particles. [Formula: see text] fixation inside sinking particles is mainly fueled by [Formula: see text] respiration rather than [Formula: see text] respiration. Our model suggests that anaerobic processes, including heterotrophic [Formula: see text] fixation, can take place in anoxic microenvironments inside sinking particles even in fully oxygenated marine waters. The modelled [Formula: see text] fixation rates are similar to bulk rates measured in the aphotic ocean, and our study consequently suggests that particle-associated heterotrophic [Formula: see text] fixation contributes significantly to oceanic [Formula: see text] fixation.
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Affiliation(s)
- Subhendu Chakraborty
- grid.5254.60000 0001 0674 042XDepartment of Biology, Marine Biological Section, University of Copenhagen, Helsingør, Denmark ,grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark ,grid.461729.f0000 0001 0215 3324Present Address: Systems Ecology Group, Leibniz Centre for Tropical Marine Research (ZMT), Bremen, Germany
| | - Ken H. Andersen
- grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark
| | - André W. Visser
- grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark
| | - Keisuke Inomura
- grid.20431.340000 0004 0416 2242Graduate School of Oceanography, University of Rhode Island, Narragansett, RI USA
| | - Michael J. Follows
- grid.116068.80000 0001 2341 2786Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA USA
| | - Lasse Riemann
- grid.5254.60000 0001 0674 042XDepartment of Biology, Marine Biological Section, University of Copenhagen, Helsingør, Denmark
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25
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Li M, Cheng L, Tang J, Daroch M. Molecular Components of Nitrogen Fixation Gene Cluster and Associated Enzymatic Activities of Non-Heterocystous Thermophilic Cyanobacterium Thermoleptolyngbya sp. Life (Basel) 2021; 11:640. [PMID: 34209262 PMCID: PMC8307165 DOI: 10.3390/life11070640] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/18/2021] [Accepted: 06/24/2021] [Indexed: 11/17/2022] Open
Abstract
Thermoleptolyngbya is a genus of non-heterocystous cyanobacteria that are typical inhabitants of hot spring microbial mats. These filamentous cyanobacteria are capable of nitrogen fixation. In this study, we examined the genome sequences of five publicly available Thermoleptolyngbya strains to explore their nitrogen fixation gene cluster. Analysis of the nitrogen-fixation clusters in these extremophilic strains revealed that the cluster is located in a single locus in Thermoleptolyngbyace. The average nucleotide and amino acid identities of the nitrogen-fixation cluster combined with phylogenetic reconstructions support that nitrogen fixation genes in Thermoleptolyngbyaceae are closely related to one another but also heterogeneous within the genus. The strains from Asia, and China more specifically, generate a separate clade within the genus. Among these strains Thermoleptolyngbya sp. PKUAC-SCTB121 has been selected for experimental validation of clade's nitrogen fixation capacity. The acetylene reduction experiments of that strain shown that the strain can reduce acetylene to ethylene, indicating a fully functional nitrogenase. The activity of nitrogenase has been tested using different gas compositions across 72 h and exhibited a two-phase trend, high nitrogenase activity at the beginning of the assay that slowed down in the second phase of the analysis.
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Affiliation(s)
- Meijin Li
- School of Environment and Energy, Peking University Shenzhen Graduate School, 2199 Lishui Rd., Shenzhen 518055, China;
| | - Lei Cheng
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology & Business University, Beijing 100048, China;
| | - Jie Tang
- School of Food and Bioengineering, Chengdu University, Chengdu 610106, China;
| | - Maurycy Daroch
- School of Environment and Energy, Peking University Shenzhen Graduate School, 2199 Lishui Rd., Shenzhen 518055, China;
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26
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Tilstra A, Roth F, El-Khaled YC, Pogoreutz C, Rädecker N, Voolstra CR, Wild C. Relative abundance of nitrogen cycling microbes in coral holobionts reflects environmental nitrate availability. ROYAL SOCIETY OPEN SCIENCE 2021; 8:201835. [PMID: 34109033 PMCID: PMC8170195 DOI: 10.1098/rsos.201835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 05/14/2021] [Indexed: 06/12/2023]
Abstract
Recent research suggests that nitrogen (N) cycling microbes are important for coral holobiont functioning. In particular, coral holobionts may acquire bioavailable N via prokaryotic dinitrogen (N2) fixation or remove excess N via denitrification activity. However, our understanding of environmental drivers on these processes in hospite remains limited. Employing the strong seasonality of the central Red Sea, this study assessed the effects of environmental parameters on the proportional abundances of N cycling microbes associated with the hard corals Acropora hemprichii and Stylophora pistillata. Specifically, we quantified changes in the relative ratio between nirS and nifH gene copy numbers, as a proxy for seasonal shifts in denitrification and N2 fixation potential in corals, respectively. In addition, we assessed coral tissue-associated Symbiodiniaceae cell densities and monitored environmental parameters to provide a holobiont and environmental context, respectively. While ratios of nirS to nifH gene copy numbers varied between seasons, they revealed similar seasonal patterns in both coral species, with ratios closely following patterns in environmental nitrate availability. Symbiodiniaceae cell densities aligned with environmental nitrate availability, suggesting that the seasonal shifts in nirS to nifH gene abundance ratios were probably driven by nitrate availability in the coral holobiont. Thereby, our results suggest that N cycling in coral holobionts probably adjusts to environmental conditions by increasing and/or decreasing denitrification and N2 fixation potential according to environmental nitrate availability. Microbial N cycling may, thus, extenuate the effects of changes in environmental nitrate availability on coral holobionts to support the maintenance of the coral-Symbiodiniaceae symbiosis.
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Affiliation(s)
- Arjen Tilstra
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
| | - Florian Roth
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
- Baltic Sea Centre, Stockholm University, Stockholm, Sweden
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Yusuf C. El-Khaled
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
| | - Claudia Pogoreutz
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Nils Rädecker
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
- Department of Biology, University of Konstanz, Konstanz, Germany
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Christian R. Voolstra
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Christian Wild
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
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27
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Landa M, Turk-Kubo KA, Cornejo-Castillo FM, Henke BA, Zehr JP. Critical Role of Light in the Growth and Activity of the Marine N 2-Fixing UCYN-A Symbiosis. Front Microbiol 2021; 12:666739. [PMID: 34025621 PMCID: PMC8139342 DOI: 10.3389/fmicb.2021.666739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/08/2021] [Indexed: 11/27/2022] Open
Abstract
The unicellular N2-fixing cyanobacteria UCYN-A live in symbiosis with haptophytes in the Braarudosphaera bigelowii lineage. Maintaining N2-fixing symbioses between two unicellular partners requires tight coordination of multiple biological processes including cell growth and division and, in the case of the UCYN-A symbiosis, N2 fixation of the symbiont and photosynthesis of the host. In this system, it is thought that the host photosynthesis supports the high energetic cost of N2 fixation, and both processes occur during the light period. However, information on this coordination is very limited and difficult to obtain because the UCYN-A symbiosis has yet to be available in culture. Natural populations containing the UCYN-A2 symbiosis were manipulated to explore the effects of alterations of regular light and dark periods and inhibition of host photosynthesis on N2 fixation (single cell N2 fixation rates), nifH gene transcription, and UCYN-A2 cell division (fluorescent in situ hybridization and nifH gene abundances). The results showed that the light period is critical for maintenance of regular patterns of gene expression, N2 fixation and symbiont replication and cell division. This study suggests a crucial role for the host as a producer of fixed carbon, rather than light itself, in the regulation and implementation of these cellular processes in UCYN-A.
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Affiliation(s)
- Marine Landa
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Kendra A Turk-Kubo
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, United States
| | | | - Britt A Henke
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, United States
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28
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Khademian M, Imlay JA. How Microbes Evolved to Tolerate Oxygen. Trends Microbiol 2021; 29:428-440. [PMID: 33109411 PMCID: PMC8043972 DOI: 10.1016/j.tim.2020.10.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/03/2020] [Accepted: 10/05/2020] [Indexed: 12/24/2022]
Abstract
Ancient microbes invented biochemical mechanisms and assembled core metabolic pathways on an anoxic Earth. Molecular oxygen appeared far later, forcing microbes to devise layers of defensive tactics that fend off the destructive actions of both reactive oxygen species (ROS) and oxygen itself. Recent work has pinpointed the enzymes that ROS attack, plus an array of clever protective strategies that abet the well known scavenging systems. Oxygen also directly damages the low-potential metal centers and radical-based mechanisms that optimize anaerobic metabolism; therefore, committed anaerobes have evolved customized tactics that defend these various enzymes from occasional oxygen exposure. Thus a more comprehensive, detailed, and surprising view of oxygen toxicity is coming into view.
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Affiliation(s)
- Maryam Khademian
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
| | - James A Imlay
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
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29
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Garg R, Maldener I. The Dual Role of the Glycolipid Envelope in Different Cell Types of the Multicellular Cyanobacterium Anabaena variabilis ATCC 29413. Front Microbiol 2021; 12:645028. [PMID: 33897656 PMCID: PMC8064123 DOI: 10.3389/fmicb.2021.645028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Anabaena variabilis is a filamentous cyanobacterium that is capable to differentiate specialized cells, the heterocysts and akinetes, to survive under different stress conditions. Under nitrogen limited condition, heterocysts provide the filament with nitrogen by fixing N2. Akinetes are spore-like dormant cells that allow survival during adverse environmental conditions. Both cell types are characterized by the presence of a thick multilayered envelope, including a glycolipid layer. While in the heterocyst this glycolipid layer is required for the maintenance of a microoxic environment and nitrogen fixation, its function in akinetes is completely unknown. Therefore, we constructed a mutant deficient in glycolipid synthesis and investigated the performance of heterocysts and akinetes in that mutant strain. We chose to delete the gene Ava_2595, which is homolog to the known hglB gene, encoding a putative polyketide synthase previously shown to be involved in heterocyst glycolipid synthesis in Anabaena sp. PCC 7120, a species which does not form akinetes. Under the respective conditions, the Ava_2595 null mutant strain formed aberrant heterocysts and akinete-like cells, in which the specific glycolipid layers were absent. This confirmed firstly that both cell types use a glycolipid of identical chemical composition in their special envelopes and, secondly, that HglB is essential for glycolipid synthesis in both types of differentiated cells. As a consequence, the mutant was not able to fix N2 and to grow under diazotrophic conditions. Furthermore, the akinetes lacking the glycolipids showed a severely reduced tolerance to stress conditions, but could germinate normally under standard conditions. This demonstrates the importance of the glycolipid layer for the ability of akinetes as spore-like dormant cells to withstand freezing, desiccation, oxidative stress and attack by lytic enzymes. Our study established the dual role of the glycolipid layer in fulfilling different functions in the evolutionary-related specialized cells of cyanobacteria. It also indicates the existence of a common pathway involving HglB for the synthesis of glycolipids in heterocysts and akinetes.
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Affiliation(s)
- Ritu Garg
- Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Tübingen, Germany
| | - Iris Maldener
- Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Tübingen, Germany
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30
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Rabouille S, Campbell DA, Masuda T, Zavřel T, Bernát G, Polerecky L, Halsey K, Eichner M, Kotabová E, Stephan S, Lukeš M, Claquin P, Bonomi-Barufi J, Lombardi AT, Červený J, Suggett DJ, Giordano M, Kromkamp JC, Prášil O. Electron & Biomass Dynamics of Cyanothece Under Interacting Nitrogen & Carbon Limitations. Front Microbiol 2021; 12:617802. [PMID: 33897635 PMCID: PMC8063122 DOI: 10.3389/fmicb.2021.617802] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/01/2021] [Indexed: 11/25/2022] Open
Abstract
Marine diazotrophs are a diverse group with key roles in biogeochemical fluxes linked to primary productivity. The unicellular, diazotrophic cyanobacterium Cyanothece is widely found in coastal, subtropical oceans. We analyze the consequences of diazotrophy on growth efficiency, compared to NO3–-supported growth in Cyanothece, to understand how cells cope with N2-fixation when they also have to face carbon limitation, which may transiently affect populations in coastal environments or during blooms of phytoplankton communities. When grown in obligate diazotrophy, cells face the double burden of a more ATP-demanding N-acquisition mode and additional metabolic losses imposed by the transient storage of reducing potential as carbohydrate, compared to a hypothetical N2 assimilation directly driven by photosynthetic electron transport. Further, this energetic burden imposed by N2-fixation could not be alleviated, despite the high irradiance level within the cultures, because photosynthesis was limited by the availability of dissolved inorganic carbon (DIC), and possibly by a constrained capacity for carbon storage. DIC limitation exacerbates the costs on growth imposed by nitrogen fixation. Therefore, the competitive efficiency of diazotrophs could be hindered in areas with insufficient renewal of dissolved gases and/or with intense phytoplankton biomass that both decrease available light energy and draw the DIC level down.
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Affiliation(s)
- Sophie Rabouille
- Sorbonne Université, CNRS, LOV, Villefranche-sur-Mer, France.,Sorbonne Université, CNRS, LOMIC, Banyuls-sur-Mer, France
| | - Douglas A Campbell
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Mount Allison University, Sackville, NB, Canada
| | - Takako Masuda
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Tomáš Zavřel
- Department of Adaptive Biotechnologies, Global Change Research Institute CAS, Brno, Czechia
| | - Gábor Bernát
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Centre for Ecological Research, Balaton Limnological Institute, Klebelsberg Kuno u. 3. 8237 Tihany, Hungary
| | - Lubos Polerecky
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Kimberly Halsey
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Meri Eichner
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Eva Kotabová
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Susanne Stephan
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Zur alten Fischerhütte 2, Stechlin, Germany.,Department of Ecology, Berlin Institute of Technology (TU Berlin), Ernst-Reuter-Platz 1, Berlin, Germany
| | - Martin Lukeš
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Pascal Claquin
- UMR BOREA (CNRS 8067), MNHN, IRD (207), Université de Caen Basse-Normandie, Caen, France
| | - José Bonomi-Barufi
- Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | | | - Jan Červený
- Department of Adaptive Biotechnologies, Global Change Research Institute CAS, Brno, Czechia
| | - David J Suggett
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | - Mario Giordano
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Dipartimento di Scienze della Vita e dell'Ambiente, UniversitaÌ Politecnica delle Marche, Ancona, Italy
| | - Jacco C Kromkamp
- NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Utrecht, Netherlands
| | - Ondřej Prášil
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
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31
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Seasonal and long-term effects of nutrient additions and liming on the nifH gene in cerrado soils under native vegetation. iScience 2021; 24:102349. [PMID: 33870141 PMCID: PMC8044383 DOI: 10.1016/j.isci.2021.102349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/02/2020] [Accepted: 03/18/2021] [Indexed: 11/20/2022] Open
Abstract
Biological nitrogen fixation (BNF) represents the main input source of N in tropical savannas. BNF could be particularly important for Brazilian savannas (known as Cerrado) that show a highly conservative N cycle. We evaluated the effects of seasonal precipitation and nutrient additions on the nifH gene abundance in soils from a long-term fertilization experiment in a Cerrado's native area. The experiment consists of five treatments: (1) control, (2) liming, (3) nitrogen (N), (4) nitrogen + phosphorus (NP), and (5) phosphorus (P) additions. The nifH gene sequence was related to Bradyrhizobium members. Seasonal effects on N-fixing potential were observed by a decrease in the nifH relative abundance from rainy to dry season in control, N, and NP treatments. A significant reduction in nifH abundance was found in the liming treatment in both seasons. The findings evidenced the multiple factors controlling the potential N-fixing by free-living diazotrophs in these nutrient-limited and seasonally dry ecosystems.
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32
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Osburn FS, Wagner ND, Scott JT. Biological stoichiometry and growth dynamics of a diazotrophic cyanobacteria in nitrogen sufficient and deficient conditions. HARMFUL ALGAE 2021; 103:102011. [PMID: 33980450 PMCID: PMC8119935 DOI: 10.1016/j.hal.2021.102011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
The role of nitrogen (N) fixation in determining the frequency, magnitude, and extent of harmful algal blooms (HABs) has not been well studied. Dolichospermum is a common HAB species that is diazotrophic (capable of N fixation) and thus growth is often considered never to be limited by low combined N sources. However, N fixation is energetically expensive and its cost during bloom formation has not been quantified. Additionally, it is unknown how acclimation to differing nutrient ratios affects growth and cellular carbon (C):N stoichiometry. Here, we test the hypotheses that diazotrophic cyanobacteria are homeostatic for N because of their ability to fix atmospheric N2 and that previous acclimation to low N environments will result in more fixed N and lower C:N stoichiometry. Briefly, cultures that varied in resource N:phosphorus (P) ranging from 0.01 to 100 (atom), were seeded with Dolichospermum which were previously acclimated to low and high N:P conditions and then sampled temporally for growth and C:N stoichiometry. We found that Dolichospermum was not homeostatic for N and displayed classic signs of N limitation and elevated C:N stoichiometry, highlighting the necessary growth trade-off within cells when expending energy to fix N. Acclimation to N limited conditions caused differences in both C:N and fixed N at various time points in the experiment. These results highlight the importance of environmentally available N to a diazotrophic bloom, as well as how previous growth conditions can influence population growth during blooms experiencing variable N:P.
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Affiliation(s)
- Felicia S Osburn
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA.
| | - Nicole D Wagner
- Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
| | - J Thad Scott
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
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33
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Nitrogen Sources and Iron Availability Affect Pigment Biosynthesis and Nutrient Consumption in Anabaena sp. UTEX 2576. Microorganisms 2021; 9:microorganisms9020431. [PMID: 33669780 PMCID: PMC7922959 DOI: 10.3390/microorganisms9020431] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 11/17/2022] Open
Abstract
Anabaena sp. UTEX 2576 metabolizes multiple nitrogen (N) sources and is deemed a biotechnological platform for chemical production. Cyanobacteria have been identified as prolific producers of biofertilizers, biopolymers, biofuels, and other bioactive compounds. Here, we analyze the effect of different N-sources and Fe availability on the bioproduction of phycobiliproteins and β-carotene. We characterize nutrient demand in modified BG11 media, including data on CO2 fixation rates, N-source consumption, and mineral utilization (e.g., phosphorus (P), and 11 metallic elements). Results suggest that non-diazotrophic cultures grow up to 60% faster than diazotrophic cells, resulting in 20% higher CO2-fixation rates. While the production of β-carotene was maximum in medium with NaNO3, Fe starvation increased the cellular abundance of C-phycocyanin and allophycocyanin by at least 22%. Compared to cells metabolizing NaNO3 and N2, cultures adapted to urea media increased their P, calcium and manganese demands by at least 72%, 97% and 76%, respectively. Variations on pigmentation and nutrient uptake were attributed to changes in phycocyanobilin biosynthesis, light-induced oxidation of carotenoids, and urea-promoted peroxidation. This work presents insights into developing optimal Anabaena culture for efficient operations of bioproduction and wastewater bioremediation with cyanobacteria.
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34
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Inomura K, Deutsch C, Masuda T, Prášil O, Follows MJ. Quantitative models of nitrogen-fixing organisms. Comput Struct Biotechnol J 2020; 18:3905-3924. [PMID: 33335688 PMCID: PMC7733014 DOI: 10.1016/j.csbj.2020.11.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 10/26/2022] Open
Abstract
Nitrogen-fixing organisms are of importance to the environment, providing bioavailable nitrogen to the biosphere. Quantitative models have been used to complement the laboratory experiments and in situ measurements, where such evaluations are difficult or costly. Here, we review the current state of the quantitative modeling of nitrogen-fixing organisms and ways to enhance the bridge between theoretical and empirical studies.
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Affiliation(s)
- Keisuke Inomura
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Curtis Deutsch
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Michael J. Follows
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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35
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Zulkefli NS, Hwang SJ. Heterocyst Development and Diazotrophic Growth of Anabaena variabilis under Different Nitrogen Availability. Life (Basel) 2020; 10:E279. [PMID: 33202779 PMCID: PMC7696877 DOI: 10.3390/life10110279] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/09/2020] [Accepted: 11/11/2020] [Indexed: 11/17/2022] Open
Abstract
Nitrogen is globally limiting primary production in the ocean, but some species of cyanobacteria can carry out nitrogen (N) fixation using specialized cells known as heterocysts. However, the effect of N sources and their availability on heterocyst development is not yet fully understood. This study aimed to evaluate the effect of various inorganic N sources on the heterocyst development and cellular growth in an N-fixing cyanobacterium, Anabaena variabilis. Growth rate, heterocyst development, and cellular N content of the cyanobacteria were examined under varying nitrate and ammonium concentrations. A. variabilis exhibited high growth rate both in the presence and absence of N sources regardless of their concentration. Ammonium was the primary source of N in A. variabilis. Even the highest concentrations of both nitrate (1.5 g L-1 as NaNO3) and ammonium (0.006 g L-1 as Fe-NH4-citrate) did not exhibit an inhibitory effect on heterocyst development. Heterocyst production positively correlated with the cell N quota and negatively correlated with vegetative cell growth, indicating that both of the processes were interdependent. Taken together, N deprivation triggers heterocyst production for N fixation. This study outlines the difference in heterocyst development and growth in A. variabilis under different N sources.
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Affiliation(s)
| | - Soon-Jin Hwang
- Department of Environmental Health Science and Human and Eco-care Center, Konkuk University, Seoul 05029, Korea
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36
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Soumare A, Diedhiou AG, Thuita M, Hafidi M, Ouhdouch Y, Gopalakrishnan S, Kouisni L. Exploiting Biological Nitrogen Fixation: A Route Towards a Sustainable Agriculture. PLANTS 2020; 9:plants9081011. [PMID: 32796519 PMCID: PMC7464700 DOI: 10.3390/plants9081011] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/08/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022]
Abstract
For all living organisms, nitrogen is an essential element, while being the most limiting in ecosystems and for crop production. Despite the significant contribution of synthetic fertilizers, nitrogen requirements for food production increase from year to year, while the overuse of agrochemicals compromise soil health and agricultural sustainability. One alternative to overcome this problem is biological nitrogen fixation (BNF). Indeed, more than 60% of the fixed N on Earth results from BNF. Therefore, optimizing BNF in agriculture is more and more urgent to help meet the demand of the food production needs for the growing world population. This optimization will require a good knowledge of the diversity of nitrogen-fixing microorganisms, the mechanisms of fixation, and the selection and formulation of efficient N-fixing microorganisms as biofertilizers. Good understanding of BNF process may allow the transfer of this ability to other non-fixing microorganisms or to non-leguminous plants with high added value. This minireview covers a brief history on BNF, cycle and mechanisms of nitrogen fixation, biofertilizers market value, and use of biofertilizers in agriculture. The minireview focuses particularly on some of the most effective microbial products marketed to date, their efficiency, and success-limiting in agriculture. It also highlights opportunities and difficulties of transferring nitrogen fixation capacity in cereals.
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Affiliation(s)
- Abdoulaye Soumare
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratoire Commun de Microbiologie (LCM) IRD/ISRA/UCAD, Centre de Recherche de Bel Air, Dakar 1386, Senegal
- Correspondence: (A.S.); (A.G.D.)
| | - Abdala G. Diedhiou
- Laboratoire Commun de Microbiologie (LCM) IRD/ISRA/UCAD, Centre de Recherche de Bel Air, Dakar 1386, Senegal
- Département de Biologie Végétale, Faculté des Sciences et Techniques, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar 1386, Senegal
- Centre d’Excellence Africain en Agriculture pour la Sécurité Alimentaire et Nutritionnelle (CEA-AGRISAN), UCAD, Dakar 18524, Senegal
- Correspondence: (A.S.); (A.G.D.)
| | - Moses Thuita
- International Institute of Tropical Agriculture, Nairobi PO BOX 30772-00100, Kenya;
| | - Mohamed Hafidi
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratory of Microbial Biotechnologies, Agrosciences and Environment, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco
| | - Yedir Ouhdouch
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratory of Microbial Biotechnologies, Agrosciences and Environment, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco
| | | | - Lamfeddal Kouisni
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
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Diazotrophic Anaeromyxobacter Isolates from Soils. Appl Environ Microbiol 2020; 86:AEM.00956-20. [PMID: 32532868 DOI: 10.1128/aem.00956-20] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/04/2020] [Indexed: 11/20/2022] Open
Abstract
Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase (nifBHDKEN). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N2-dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N2 gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N2 gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter, which is a common soil bacterium.IMPORTANCE Anaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N2-dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter, which is a common bacterium in soils.
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Fernandez L, Peura S, Eiler A, Linz AM, McMahon KD, Bertilsson S. Diazotroph Genomes and Their Seasonal Dynamics in a Stratified Humic Bog Lake. Front Microbiol 2020; 11:1500. [PMID: 32714313 PMCID: PMC7341956 DOI: 10.3389/fmicb.2020.01500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 06/09/2020] [Indexed: 12/28/2022] Open
Abstract
Aquatic N-fixation is generally associated with the growth and mass development of Cyanobacteria in nitrogen-deprived photic zones. However, sequenced genomes and environmental surveys suggest active aquatic N-fixation also by many non-cyanobacterial groups. Here, we revealed the seasonal variation and genomic diversity of potential N-fixers in a humic bog lake using metagenomic data and nif gene clusters analysis. Groups with diazotrophic operons were functionally divergent and included Cholorobi, Geobacter, Desulfobacterales, Methylococcales, and Acidobacteria. In addition to nifH (a gene that encodes the dinitrogenase reductase component of the molybdenum nitrogenase), we also identified sequences corresponding to vanadium and iron-only nitrogenase genes. Within the Chlorobi population, the nitrogenase (nifH) cluster was included in a well-structured retrotransposon. Furthermore, the presence of light-harvesting photosynthesis genes implies that anoxygenic photosynthesis may fuel nitrogen fixation under the prevailing low-irradiance conditions. The presence of rnf genes (related to the expression of H+/Na+-translocating ferredoxin: NAD+ oxidoreductase) in Methylococcales and Desulfobacterales suggests that other energy-generating processes may drive the costly N-fixation in the absence of photosynthesis. The highly reducing environment of the anoxic bottom layer of Trout Bog Lake may thus also provide a suitable niche for active N-fixers and primary producers. While future studies on the activity of these potential N-fixers are needed to clarify their role in freshwater nitrogen cycling, the metagenomic data presented here enabled an initial characterization of previously overlooked diazotrophs in freshwater biomes.
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Affiliation(s)
- Leyden Fernandez
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Sari Peura
- Department of Forest Mycology and Plant Pathology, Science for Life Laboratory, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Alexander Eiler
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
- Centre for Biogeochemistry in the Anthropocene, Department of Biosciences, Section for Aquatic Biology and Toxicology, University of Oslo, Oslo, Norway
| | - Alexandra M. Linz
- Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin–Madison, Madison, WI, United States
| | - Katherine D. McMahon
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, WI, United States
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Heterogeneous nitrogen fixation rates confer energetic advantage and expanded ecological niche of unicellular diazotroph populations. Commun Biol 2020; 3:172. [PMID: 32286494 PMCID: PMC7156374 DOI: 10.1038/s42003-020-0894-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/13/2020] [Indexed: 11/23/2022] Open
Abstract
Nitrogen fixing plankton provide nitrogen to fuel marine ecosystems and biogeochemical cycles but the factors that constrain their growth and habitat remain poorly understood. Here we investigate the importance of metabolic specialization in unicellular diazotroph populations, using laboratory experiments and model simulations. In clonal cultures of Crocosphaera watsonii and Cyanothece sp. spiked with 15N2, cellular 15N enrichment developed a bimodal distribution within colonies, indicating that N2 fixation was confined to a subpopulation. In a model of population metabolism, heterogeneous nitrogen (N2) fixation rates substantially reduce the respiration rate required to protect nitrogenase from O2. The energy savings from metabolic specialization is highest at slow growth rates, allowing populations to survive in deeper waters where light is low but nutrients are high. Our results suggest that heterogeneous N2 fixation in colonies of unicellular diazotrophs confers an energetic advantage that expands the ecological niche and may have facilitated the evolution of multicellular diazotrophs. Takako Masuda et al. show that individual cells in clonal populations of Crocosphaera watsonii and Cyanothece sp exhibit varied nitrogen fixation rates. This heterogeneity within the population decreases the energetic cost of respiration and expands the viable habitats for these unicellular diazotrophs.
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40
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Dillon ML, Hawes I, Jungblut AD, Mackey TJ, Eisen JA, Doran PT, Sumner DY. Environmental control on the distribution of metabolic strategies of benthic microbial mats in Lake Fryxell, Antarctica. PLoS One 2020; 15:e0231053. [PMID: 32282803 PMCID: PMC7153904 DOI: 10.1371/journal.pone.0231053] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 03/15/2020] [Indexed: 11/19/2022] Open
Abstract
Ecological theories posit that heterogeneity in environmental conditions greatly affects community structure and function. However, the degree to which ecological theory developed using plant- and animal-dominated systems applies to microbiomes is unclear. Investigating the metabolic strategies found in microbiomes are particularly informative for testing the universality of ecological theories because microorganisms have far wider metabolic capacity than plants and animals. We used metagenomic analyses to explore the relationships between the energy and physicochemical gradients in Lake Fryxell and the metabolic capacity of its benthic microbiome. Statistical analysis of the relative abundance of metabolic marker genes and gene family diversity shows that oxygenic photosynthesis, carbon fixation, and flavin-based electron bifurcation differentiate mats growing in different environmental conditions. The pattern of gene family diversity points to the likely importance of temporal environmental heterogeneity in addition to resource gradients. Overall, we found that the environmental heterogeneity of photosynthetically active radiation (PAR) and oxygen concentration ([O2]) in Lake Fryxell provide the framework by which metabolic diversity and composition of the community is structured, in accordance with its phylogenetic structure. The organization of the resulting microbial ecosystems are consistent with the maximum power principle and the species sorting model.
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Affiliation(s)
- Megan L. Dillon
- Ecology Department, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, United States of America
| | - Ian Hawes
- Coastal Marine Field Station, University of Waikato, Hamilton, Waikato, New Zealand
| | - Anne D. Jungblut
- Life Sciences Department, Natural History Museum, London, England, United Kingdom
| | - Tyler J. Mackey
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Jonathan A. Eisen
- Department of Evolution and Ecology, University of California, Davis, Davis, California, United States of America
| | - Peter T. Doran
- Geology and Geophysics Department, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Dawn Y. Sumner
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, United States of America
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Yeast engineered translucent cell wall to provide its endosymbiont cyanobacteria with light. Arch Microbiol 2020; 202:1317-1325. [PMID: 32140734 DOI: 10.1007/s00203-020-01835-w] [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: 05/08/2019] [Revised: 01/19/2020] [Accepted: 02/12/2020] [Indexed: 10/24/2022]
Abstract
In this study, relationship between translucent property of yeast cell wall and occurrence of cyanobacteria inside the yeast vacuole was examined. Microscopic observations on fruit yeast Candida tropicalis showed occurrence of bacterium-like bodies inside the yeast vacuole. Appearance of vacuoles as distinct cavities indicated the perfect harvesting of light by the yeast's cell wall. Transmission electron microscopy observation showed electron-dense outer and electron-lucent inner layers in yeast cell wall. Cyanobacteria-specific 16S rRNA gene was amplified from total DNA of yeast. Cultivation of yeast in distilled water led to excision of intracellular bacteria which grew on cyanobacteria-specific medium. Examination of wet mount and Gram-stained preparations of excised bacteria showed typical bead-like trichomes. Amplification of cyanobacteria-specific genes, 16S rRNA, cnfR and dxcf, confirmed bacterial identity as Leptolyngbya boryana. These results showed that translucent cell wall of yeast has been engineered through evolution for receiving light for vital activities of cyanobacteria.
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42
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Li Y, Wang D, Chen S, Yu Z, Liu L, Wang M, Chen Z. N 2 fixation in urbanization area rivers: spatial-temporal variations and influencing factors. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:7211-7221. [PMID: 31879888 DOI: 10.1007/s11356-019-06780-w] [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: 06/10/2019] [Accepted: 10/15/2019] [Indexed: 06/10/2023]
Abstract
While nitrogen (N2) fixation is an important process in nitrogen (N) biogeochemical cycling, supplying a significant portion of the N in natural ecosystems, few quantitative constraints exist concerning its contribution to the N enrichment and export from river ecosystems. This study estimates the N2 fixation rates of urban rivers in the Yangtze Estuary area using acetylene reduction. The results demonstrate that the prominent spatiotemporal variability of river N2 fixation rates is driven by various environmental factors. River N2 fixation rates are significantly higher in the summer (90.57 ± 14.60 ngN·L-1·h-1) than in the winter (57.98 ± 15.73 ngN·L-1·h-1). Spatially, rivers draining urban and suburban areas have higher N2 fixation rates than those draining rural areas. The N2 fixation rates are positively correlated with the N2 fixing cyanobacteria density, water temperature, light, and the water phosphorus (P) concentration, but they are negatively correlated with the dissolved N concentration (NH4+-N and NO3--N). The N2 fixation rates annually range from 53.20 to 89.24 ngN·L-1·h-1 for all of the sampling rivers, which is equivalent to a depth integrated (0-0.6 m) N input of 0.163-0.274 gN·m-2·a-1. The determined annual N input via N2 fixation is generally higher than that of marine systems, but it is lower than that of eutrophic lakes. This study provides robust evidence that N2 fixation can supply a substantial portion of the N input to human-impacted river ecosystems, which has not been sufficiently accounted for when determining the N mass balance of riverine ecosystems. A high N2 fixation rate may increase the ratio of N to P input to river systems, and therefore render P the limiting factor in aquatic eutrophication.
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Affiliation(s)
- Yu Li
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China
| | - Dongqi Wang
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China.
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China.
| | - Shu Chen
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China
| | - Zhongjie Yu
- Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN, 55108, USA
| | - Lijie Liu
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China
| | - Meng Wang
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China
| | - Zhenlou Chen
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
- School of Geographical Sciences, East China Normal University, Shanghai, 200241, China
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Till P, Toepel J, Bühler B, Mach RL, Mach-Aigner AR. Regulatory systems for gene expression control in cyanobacteria. Appl Microbiol Biotechnol 2020; 104:1977-1991. [PMID: 31965222 PMCID: PMC7007895 DOI: 10.1007/s00253-019-10344-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/21/2019] [Accepted: 12/28/2019] [Indexed: 11/24/2022]
Abstract
As photosynthetic microbes, cyanobacteria are attractive hosts for the production of high-value molecules from CO2 and light. Strategies for genetic engineering and tightly controlled gene expression are essential for the biotechnological application of these organisms. Numerous heterologous or native promoter systems were used for constitutive and inducible expression, yet many of them suffer either from leakiness or from a low expression output. Anyway, in recent years, existing systems have been improved and new promoters have been discovered or engineered for cyanobacteria. Moreover, alternative tools and strategies for expression control such as riboswitches, riboregulators or genetic circuits have been developed. In this mini-review, we provide a broad overview on the different tools and approaches for the regulation of gene expression in cyanobacteria and explain their advantages and disadvantages.
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Affiliation(s)
- Petra Till
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
| | - Jörg Toepel
- Department of Solar Materials, Helmholtz-Centre for Environmental Research GmbH-UFZ, Permoserstrasse 15, 04318, Leipzig, Germany
| | - Bruno Bühler
- Department of Solar Materials, Helmholtz-Centre for Environmental Research GmbH-UFZ, Permoserstrasse 15, 04318, Leipzig, Germany
| | - Robert L Mach
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
| | - Astrid R Mach-Aigner
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria.
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria.
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Inomura K, Follett CL, Masuda T, Eichner M, Prášil O, Deutsch C. Carbon Transfer from the Host Diatom Enables Fast Growth and High Rate of N 2 Fixation by Symbiotic Heterocystous Cyanobacteria. PLANTS (BASEL, SWITZERLAND) 2020; 9:E192. [PMID: 32033207 PMCID: PMC7076409 DOI: 10.3390/plants9020192] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/20/2020] [Accepted: 01/30/2020] [Indexed: 12/25/2022]
Abstract
Diatom-diazotroph associations (DDAs) are symbioses where trichome-forming cyanobacteria support the host diatom with fixed nitrogen through dinitrogen (N2) fixation. It is inferred that the growth of the trichomes is also supported by the host, but the support mechanism has not been fully quantified. Here, we develop a coarse-grained, cellular model of the symbiosis between Hemiaulus and Richelia (one of the major DDAs), which shows that carbon (C) transfer from the diatom enables a faster growth and N2 fixation rate by the trichomes. The model predicts that the rate of N2 fixation is 5.5 times that of the hypothetical case without nitrogen (N) transfer to the host diatom. The model estimates that 25% of fixed C from the host diatom is transferred to the symbiotic trichomes to support the high rate of N2 fixation. In turn, 82% of N fixed by the trichomes ends up in the host. Modeled C fixation from the vegetative cells in the trichomes supports only one-third of their total C needs. Even if we ignore the C cost for N2 fixation and for N transfer to the host, the total C cost of the trichomes is higher than the C supply by their own photosynthesis. Having more trichomes in a single host diatom decreases the demand for N2 fixation per trichome and thus decreases their cost of C. However, even with five trichomes, which is about the highest observed for Hemiaulus and Richelia symbiosis, the model still predicts a significant C transfer from the diatom host. These results help quantitatively explain the observed high rates of growth and N2 fixation in symbiotic trichomes relative to other aquatic diazotrophs.
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Affiliation(s)
- Keisuke Inomura
- School of Oceanography, University of Washington, 1492 NE Boat St., Seattle, WA 98105, USA;
| | - Christopher L. Follett
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, 379 81b Třeboň, Czech Republic; (T.M.); (M.E.); (O.P.)
| | - Meri Eichner
- Institute of Microbiology, The Czech Academy of Sciences, 379 81b Třeboň, Czech Republic; (T.M.); (M.E.); (O.P.)
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, 379 81b Třeboň, Czech Republic; (T.M.); (M.E.); (O.P.)
| | - Curtis Deutsch
- School of Oceanography, University of Washington, 1492 NE Boat St., Seattle, WA 98105, USA;
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Malek Shahkouhi A, Motamedian E. Reconstruction of a regulated two-cell metabolic model to study biohydrogen production in a diazotrophic cyanobacterium Anabaena variabilis ATCC 29413. PLoS One 2020; 15:e0227977. [PMID: 31978122 PMCID: PMC6980584 DOI: 10.1371/journal.pone.0227977] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 01/03/2020] [Indexed: 12/21/2022] Open
Abstract
Anabaena variabilis is a diazotrophic filamentous cyanobacterium that differentiates to heterocysts and produces hydrogen as a byproduct. Study on metabolic interactions of the two differentiated cells provides a better understanding of its metabolism especially for improving hydrogen production. To this end, a genome-scale metabolic model for Anabaena variabilis ATCC 29413, iAM957, was reconstructed and evaluated in this research. Then, the model and transcriptomic data of the vegetative and heterocyst cells were applied to construct a regulated two-cell metabolic model. The regulated model improved prediction for biomass in high radiation levels. The regulated model predicts that heterocysts provide an oxygen-free environment and then, this model was used to find strategies for improving hydrogen production in heterocysts. The predictions indicate that the removal of uptake hydrogenase improves hydrogen production which is consistent with previous empirical research. Furthermore, the regulated model proposed activation of some reactions to provide redox cofactors which are required for improving hydrogen production up to 60% by bidirectional hydrogenase.
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Affiliation(s)
- Ali Malek Shahkouhi
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
| | - Ehsan Motamedian
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
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Burford MA, Carey CC, Hamilton DP, Huisman J, Paerl HW, Wood SA, Wulff A. Perspective: Advancing the research agenda for improving understanding of cyanobacteria in a future of global change. HARMFUL ALGAE 2020; 91:101601. [PMID: 32057347 DOI: 10.1016/j.hal.2019.04.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 05/19/2023]
Abstract
Harmful cyanobacterial blooms (=cyanoHABs) are an increasing feature of many waterbodies throughout the world. Many bloom-forming species produce toxins, making them of particular concern for drinking water supplies, recreation and fisheries in waterbodies along the freshwater to marine continuum. Global changes resulting from human impacts, such as climate change, over-enrichment and hydrological alterations of waterways, are major drivers of cyanoHAB proliferation and persistence. This review advocates that to better predict and manage cyanoHABs in a changing world, researchers need to leverage studies undertaken to date, but adopt a more complex and definitive suite of experiments, observations, and models which can effectively capture the temporal scales of processes driven by eutrophication and a changing climate. Better integration of laboratory culture and field experiments, as well as whole system and multiple-system studies are needed to improve confidence in models predicting impacts of climate change and anthropogenic over-enrichment and hydrological modifications. Recent studies examining adaptation of species and strains to long-term perturbations, e.g. temperature and carbon dioxide (CO2) levels, as well as incorporating multi-species and multi-stressor approaches emphasize the limitations of approaches focused on single stressors and individual species. There are also emerging species of concern, such as toxic benthic cyanobacteria, for which the effects of global change are less well understood, and require more detailed study. This review provides approaches and examples of studies tackling the challenging issue of understanding how global changes will affect cyanoHABs, and identifies critical information needs for effective prediction and management.
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Affiliation(s)
- M A Burford
- Australian Rivers Institute, and School of Environment and Science, Griffith University, Queensland, 4111, Australia.
| | - C C Carey
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, 24061, USA
| | - D P Hamilton
- Australian Rivers Institute, and School of Environment and Science, Griffith University, Queensland, 4111, Australia
| | - J Huisman
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands
| | - H W Paerl
- Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, 28557, USA; College of Environment, Hohai University, Nanjing, 210098, China
| | - S A Wood
- Cawthron Institute, Nelson, 7010, New Zealand
| | - A Wulff
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, 40530, Gothenburg, Sweden
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Allen JF, Thake B, Martin WF. Nitrogenase Inhibition Limited Oxygenation of Earth's Proterozoic Atmosphere. TRENDS IN PLANT SCIENCE 2019; 24:1022-1031. [PMID: 31447302 DOI: 10.1016/j.tplants.2019.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/10/2019] [Accepted: 07/10/2019] [Indexed: 05/24/2023]
Abstract
Cyanobacteria produced the oxygen that began to accumulate on Earth 2.5 billion years ago, at the dawn of the Proterozoic Eon. By 2.4 billion years ago, the Great Oxidation Event (GOE) marked the onset of an atmosphere containing oxygen. The oxygen content of the atmosphere then remained low for almost 2 billion years. Why? Nitrogenase, the sole nitrogen-fixing enzyme on Earth, controls the entry of molecular nitrogen into the biosphere. Nitrogenase is inhibited in air containing more than 2% oxygen: the concentration of oxygen in the Proterozoic atmosphere. We propose that oxygen inhibition of nitrogenase limited Proterozoic global primary production. Oxygen levels increased when upright terrestrial plants isolated nitrogen fixation in soil from photosynthetic oxygen production in shoots and leaves.
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Affiliation(s)
- John F Allen
- Research Department of Genetics, Evolution and Environment, Darwin Building, University College London, Gower Street, London WC1E 6BT, UK.
| | - Brenda Thake
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - William F Martin
- Institute of Molecular Evolution, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany
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48
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Warren SD, Clair LL, Stark LR, Lewis LA, Pombubpa N, Kurbessoian T, Stajich JE, Aanderud ZT. Reproduction and Dispersal of Biological Soil Crust Organisms. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00344] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Carrell AA, Kolton M, Glass JB, Pelletier DA, Warren MJ, Kostka JE, Iversen CM, Hanson PJ, Weston DJ. Experimental warming alters the community composition, diversity, and N 2 fixation activity of peat moss (Sphagnum fallax) microbiomes. GLOBAL CHANGE BIOLOGY 2019; 25:2993-3004. [PMID: 31148286 PMCID: PMC6852288 DOI: 10.1111/gcb.14715] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 05/17/2019] [Accepted: 05/24/2019] [Indexed: 05/19/2023]
Abstract
Sphagnum-dominated peatlands comprise a globally important pool of soil carbon (C) and are vulnerable to climate change. While peat mosses of the genus Sphagnum are known to harbor diverse microbial communities that mediate C and nitrogen (N) cycling in peatlands, the effects of climate change on Sphagnum microbiome composition and functioning are largely unknown. We investigated the impacts of experimental whole-ecosystem warming on the Sphagnum moss microbiome, focusing on N2 fixing microorganisms (diazotrophs). To characterize the microbiome response to warming, we performed next-generation sequencing of small subunit (SSU) rRNA and nitrogenase (nifH) gene amplicons and quantified rates of N2 fixation activity in Sphagnum fallax individuals sampled from experimental enclosures over 2 years in a northern Minnesota, USA bog. The taxonomic diversity of overall microbial communities and diazotroph communities, as well as N2 fixation rates, decreased with warming (p < 0.05). Following warming, diazotrophs shifted from a mixed community of Nostocales (Cyanobacteria) and Rhizobiales (Alphaproteobacteria) to predominance of Nostocales. Microbiome community composition differed between years, with some diazotroph populations persisting while others declined in relative abundance in warmed plots in the second year. Our results demonstrate that warming substantially alters the community composition, diversity, and N2 fixation activity of peat moss microbiomes, which may ultimately impact host fitness, ecosystem productivity, and C storage potential in peatlands.
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Affiliation(s)
- Alyssa A. Carrell
- Bredesen Center for Interdisciplinary Research and Graduate EducationUniversity of TennesseeKnoxvilleTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Max Kolton
- School of BiologyGeorgia Institute of TechnologyAtlantaGeorgia
| | - Jennifer B. Glass
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
| | | | - Melissa J. Warren
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
- Present address:
CH2MAtlantaGeorgia30328USA
| | - Joel E. Kostka
- School of BiologyGeorgia Institute of TechnologyAtlantaGeorgia
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
| | - Colleen M. Iversen
- Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
| | - Paul J. Hanson
- Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
| | - David J. Weston
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
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