1
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Trebuch LM, Schoofs K, Vaessen SMF, Neu TR, Janssen M, Wijffels RH, Vet LEM, Fernandes TV. N 2 -fixation can sustain wastewater treatment performance of photogranules under nitrogen-limiting conditions. Biotechnol Bioeng 2023; 120:1303-1315. [PMID: 36779371 DOI: 10.1002/bit.28349] [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: 08/30/2022] [Revised: 12/23/2022] [Accepted: 02/09/2023] [Indexed: 02/14/2023]
Abstract
Wastewater characteristics can vary significantly, and in some municipal wastewaters the N:P ratio is as low as 5 resulting in nitrogen-limiting conditions. In this study, the microbial community, function, and morphology of photogranules under nitrogen-replete (N+) and limiting (N-) conditions was assessed in sequencing batch reactors. Photogranules under N- condition were nitrogen deprived 2/3 of a batch cycle duration. Surprisingly, this nitrogen limitation had no adverse effect on biomass productivity. Moreover, phosphorus and chemical oxygen demand removal were similar to their removal under N+ conditions. Although performance was similar, the difference in granule morphology was obvious. While N+ photogranules were dense and structurally confined, N- photogranules showed loose structures with occasional voids. Microbial community analysis revealed high abundance of cyanobacteria capable of N2 -fixation. These were higher at N- (38%) than N+ (29%) treatments, showing that photogranules could adjust and maintain treatment performance and high biomass productivity by means of N2 -fixation.
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Affiliation(s)
- Lukas M Trebuch
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Bioprocess Engineering, AlgaePARC Wageningen University, Wageningen, The Netherlands
| | - Kobe Schoofs
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Bioprocess Engineering, AlgaePARC Wageningen University, Wageningen, The Netherlands
| | - Stijn M F Vaessen
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Bioprocess Engineering, AlgaePARC Wageningen University, Wageningen, The Netherlands
| | - Thomas R Neu
- Microbiology of Interfaces, Department River Ecology, Helmholtz Centre for Environmental Research - UFZ, Magdeburg, Germany
| | - Marcel Janssen
- Bioprocess Engineering, AlgaePARC Wageningen University, Wageningen, The Netherlands
| | - René H Wijffels
- Bioprocess Engineering, AlgaePARC Wageningen University, Wageningen, The Netherlands.,Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Louise E M Vet
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Tânia V Fernandes
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
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2
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Touloupakis E, Zittelli GC, Benavides AMS, Torzillo G. Growth and photosynthetic performance of Nostoc linckia (formerly N. calcicola) cells grown in BG11 and BG11 0 media. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES : OFFICIAL JOURNAL OF THE EUROPEAN PHOTOCHEMISTRY ASSOCIATION AND THE EUROPEAN SOCIETY FOR PHOTOBIOLOGY 2022; 22:795-807. [PMID: 36550226 DOI: 10.1007/s43630-022-00353-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022]
Abstract
The biotechnological potential of Nostoc linckia as a biofertilizer and source of bioactive compounds makes it important to study its growth physiology and productivity. Since nitrogen is a fundamental component of N. linckia biomass, we compared the growth and biochemical composition of cultures grown in BG11 (i.e., in the presence of nitrate) and BG110 (in the absence of nitrate). Cultures grown in BG11 accumulated more cell biomass reaching a dry weight of 1.65 ± 0.06 g L-1, compared to 0.92 ± 0.01 g L-1 in BG110 after 240 h of culture. Biomass productivity was higher in culture grown in BG11 medium (average 317 ± 38 mg L-1 day-1) compared to that attained in BG110 (average 262 ± 37 mg L-1 day-1). The chlorophyll content of cells grown in BG11 increased continuously up to (39.0 ± 1.3 mg L-1), while in BG110 it increased much more slowly (13.6 ± 0.8 mg L-1). Biomass grown in BG11 had higher protein and phycobilin contents. However, despite the differences in biochemical composition and pigment concentration, between BG11 and BG110 cultures, both their net photosynthetic rates and maximum quantum yields of the photosystem II resulted in similar.
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Affiliation(s)
- Eleftherios Touloupakis
- Istituto di Ricerca sugli Ecosistemi Terrestri, CNR, Via Madonna del Piano, 10 Sesto Fiorentino, 50019, Florence, Italy
| | - Graziella Chini Zittelli
- Istituto per la Bioeconomia, CNR, Via Madonna del Piano 10 Sesto Fiorentino, 50019, Florence, Italy
| | - Ana Margarita Silva Benavides
- Centro de Investigación en Ciencias Del Mar y Limnologίa, Universidad de Costa Rica, San Pedro, San José, 2060, Costa Rica.,Escuela de Biologia, Universidad de Costa Rica, San Pedro, San José, 2060, Costa Rica
| | - Giuseppe Torzillo
- Istituto per la Bioeconomia, CNR, Via Madonna del Piano 10 Sesto Fiorentino, 50019, Florence, Italy. .,Centro de Investigación en Ciencias Del Mar y Limnologίa, Universidad de Costa Rica, San Pedro, San José, 2060, Costa Rica.
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3
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Zafar AM, Javed MA, Aly Hassan A. Unprecedented biodesalination rates-Shortcomings of electrical conductivity measurements in determining salt removal by algae and cyanobacteria. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 302:113947. [PMID: 34678537 DOI: 10.1016/j.jenvman.2021.113947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/27/2021] [Accepted: 10/14/2021] [Indexed: 06/13/2023]
Abstract
Phormidium keutzingianum performed biodesalination of brackish water (10 g/L). The electrical conductivity (EC) was measured to evaluate the salt concentration over 80 days of cyanobacterial inoculation. Anion concentrations were measured using ion chromatography to estimate salt removal. EC-based measurements showed ∼8-10% removal efficiency in the first 20 days. However, the removal efficiency based on chloride ion concentration showed ∼40% removal in the same time frame. The pH increase was observed with growth of algal biomass. The increasing pH proposes the formation of hydroxyl and carbonate ions. Sulfuric acid was added at day 110 to neutralize them. At pH 4, the EC reduced significantly to about ∼37% confirming the chloride removal. EC should not be used to measure salt reduction as it is an obscure parameter, and therefore, EC is not the best choice to measure salinity removal using algae. Some recently published studies used only EC to estimate biodesalination, and it is anticipated that salt removal is misrepresented in those studies.
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Affiliation(s)
- Abdul Mannan Zafar
- Civil and Environmental Engineering Department, United Arab Emirates University, Al-Ain, 15551, Abu Dhabi, United Arab Emirates.
| | - Muhammad Asad Javed
- Civil and Environmental Engineering Department, United Arab Emirates University, Al-Ain, 15551, Abu Dhabi, United Arab Emirates.
| | - Ashraf Aly Hassan
- Civil and Environmental Engineering Department, United Arab Emirates University, Al-Ain, 15551, Abu Dhabi, United Arab Emirates; Civil Engineering Department, University of Nebraska Lincoln, Lincoln, NE, USA.
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4
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Cross-Activation of Two Nitrogenase Gene Clusters by CnfR1 or CnfR2 in the Cyanobacterium Anabaena variabilis. Microbiol Spectr 2021; 9:e0106021. [PMID: 34612667 PMCID: PMC8510180 DOI: 10.1128/spectrum.01060-21] [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] [Indexed: 11/20/2022] Open
Abstract
In Anabaena variabilis, the nif1 genes, which are activated by CnfR1, produce a Mo-nitrogenase that is expressed only in heterocysts. Similarly, the nif2 genes, which are activated by CnfR2, make a Mo-nitrogenase that is expressed only in anaerobic vegetative cells. However, CnfR1, when it was expressed in anaerobic vegetative cells under the control of the cnfR2 promoter or from the Co2+-inducible coaT promoter, activated the expression of both nifB1 and nifB2. Activation of nifB2, but not nifB1, by CnfR1 required NtcA. Thus, expression of the nif1 system requires no heterocyst-specific factor other than CnfR1. In contrast, CnfR2, when it was expressed in heterocysts under the control of the cnfR1 promoter or from the coaT promoter, did not activate the expression of nifB1 or nifB2. Thus, activation of the nif2 system in anaerobic vegetative cells by CnfR2 requires additional factors absent in heterocysts. CnfR2 made from the coaT promoter activated nifB2 expression in anaerobic vegetative cells grown with fixed nitrogen; however, oxygen inhibited CnfR2 activation of nifB2 expression. In contrast, activation of nifB1 and nifB2 by CnfR1 was unaffected by oxygen. CnfR1, which does not activate the nifB2 promoter in heterocysts, activated the expression of the entire nif2 gene cluster from a nifB2::nifB1::nifB2 hybrid promoter in heterocysts, producing functional Nif2 nitrogenase in heterocysts. However, activity was poor compared to the normal Nif1 nitrogenase. Expression of the nif2 cluster in anaerobic vegetative cells of Nostoc sp. PCC 7120, a strain lacking the nif2 nitrogenase, resulted in expression of the nif2 genes but weak nitrogenase activity. IMPORTANCE Cyanobacterial nitrogen fixation is important in the global nitrogen cycle, in oceanic productivity, and in many plant and fungal symbioses. While the proteins that mediate nitrogen fixation have been well characterized, the regulation of this complex and expensive process is poorly understood in cyanobacteria. Using a genetic approach, we have characterized unique and overlapping functions for two homologous transcriptional activators CnfR1 and CnfR2 that activate two distinct nitrogenases in a single organism. We found that CnfR1 is promiscuous in its ability to activate both nitrogenase systems, whereas CnfR2 depends on additional cellular factors; thus, it activates only one nitrogenase system.
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Purahong W, Hossen S, Nawaz A, Sadubsarn D, Tanunchai B, Dommert S, Noll M, Ampornpan LA, Werukamkul P, Wubet T. Life on the Rocks: First Insights Into the Microbiota of the Threatened Aquatic Rheophyte Hanseniella heterophylla. FRONTIERS IN PLANT SCIENCE 2021; 12:634960. [PMID: 34194446 PMCID: PMC8238419 DOI: 10.3389/fpls.2021.634960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 04/15/2021] [Indexed: 05/15/2023]
Abstract
Little is known about microbial communities of aquatic plants despite their crucial ecosystem function in aquatic ecosystems. Here, we analyzed the microbiota of an aquatic rheophyte, Hanseniella heterophylla, growing at three areas differing in their degree of anthropogenic disturbance in Thailand employing a metabarcoding approach. Our results show that diverse taxonomic and functional groups of microbes colonize H. heterophylla. Proteobacteria, Actinobacteria, Dothideomycetes, and Sordariomycetes form the backbone of the microbiota. Surprisingly, the beneficial microbes reported from plant microbiomes in terrestrial habitats, such as N-fixing bacteria and ectomycorrhizal fungi, were also frequently detected. We showed that biofilms for attachment of H. heterophylla plants to rocks may associate with diverse cyanobacteria (distributed in eight families, including Chroococcidiopsaceae, Coleofasciculaceae, Leptolyngbyaceae, Microcystaceae, Nostocaceae, Phormidiaceae, Synechococcaceae, and Xenococcaceae) and other rock biofilm-forming bacteria (mainly Acinetobacter, Pseudomonas, and Flavobacterium). We found distinct community compositions of both bacteria and fungi at high and low anthropogenic disturbance levels regardless of the study areas. In the highly disturbed area, we found strong enrichment of Gammaproteobacteria and Tremellomycetes coupled with significant decline of total bacterial OTU richness. Bacteria involved with sulfamethoxazole (antibiotic) degradation and human pathogenic fungi (Candida, Cryptococcus, Trichosporon, and Rhodotorula) were exclusively detected as indicator microorganisms in H. heterophylla microbiota growing in a highly disturbed area, which can pose a major threat to human health. We conclude that aquatic plant microbiota are sensitive to anthropogenic disturbance. Our results also unravel the potential use of this plant as biological indicators in remediation or treatment of such disturbed ecosystems.
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Affiliation(s)
- Witoon Purahong
- Department of Soil Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
- *Correspondence: Witoon Purahong, ;
| | - Shakhawat Hossen
- Department of Soil Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
- Institute of Ecology and Evolution, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Ali Nawaz
- Department of Community Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
- Department of Civil, Geo and Environmental Engineering, Technical University of Munich, Garching, Germany
| | - Dolaya Sadubsarn
- Department of Soil Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
| | - Benjawan Tanunchai
- Department of Soil Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
| | - Sven Dommert
- Department of Soil Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
| | - Matthias Noll
- Institute for Bioanalysis, Coburg University of Applied Sciences and Arts, Coburg, Germany
| | - La-aw Ampornpan
- Department of Biology, Srinakharinwirot University, Bangkok, Thailand
| | - Petcharat Werukamkul
- Faculty of Science and Technology, Rajamangala University of Technology Phra Nakhon, Bangkok, Thailand
- Petcharat Werukamkul,
| | - Tesfaye Wubet
- Department of Community Ecology, UFZ-Helmholtz Centre for Environmental Research, Halle, Germany
- German Centre for Integrative Biodiversity Research, Halle-Jena-Leipzig, Leipzig, Germany
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6
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Osman A, Salama A, Emam Mahmoud K, Sitohy M. Alleviation of carbon tetrachloride-induced hepatocellular damage and oxidative stress in rats by Anabaena oryzae phycocyanin. J Food Biochem 2020; 45:e13562. [PMID: 33184842 DOI: 10.1111/jfbc.13562] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/21/2020] [Accepted: 10/25/2020] [Indexed: 11/26/2022]
Abstract
Phycocyanin isolated from Anabaena biomass was in-vitro assayed for its antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] free radical, revealing maximum activities amounting to 77 and 80% at 1,000 µg/ml and SC50 values about 96 and 111 µg/ml, respectively. A biological experiment was conducted, involving 40 male Wistar Albino rats, divided into five groups. Group I received only the basal diet as a normal control, while groups II, III, IV, and V were administrated intraperitoneal (IP) injection of a single dose of CCl4 (50% in corn oil) at 0.5 ml/kg body weight. Subsequently, groups II, III, IV, and V received phycocyanin at 0.0, 25, 50, and 100 mg/kg body weight/day. CCl4 induced considerable increases (p < .05) in the levels of serum ALT, AST, urea and creatinine, total lipid, and triglycerides coupled with significant reductions (p < .05) in serum antioxidant enzymes and some liver histopathological deformations compared to the negative control (group 1). Administration of Anabaena oryzae phycocyanin can counteract these CCl4 -induced changes. PRACTICAL APPLICATIONS: Phycocyanin isolated from Anabaena has beneficial effects such as the antioxidant, antibacterial, anticancer, and hepatoprotective effect. Phycocyanin may play a key role in alleviating oxidative stress, artificially induced by carbon tetrachloride in Albino rats, to ultimately determine its capacity to serve as a natural antioxidant for food and health applications.
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Affiliation(s)
- Ali Osman
- Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Ali Salama
- Microbiology Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Kamal Emam Mahmoud
- Biochemistry Department, Faculty of Agriculture, Menoufia University, Shibin El-Kom, Egypt
| | - Mahmoud Sitohy
- Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
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7
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Mareš J, Johansen JR, Hauer T, Zima J, Ventura S, Cuzman O, Tiribilli B, Kaštovský J. Taxonomic resolution of the genus Cyanothece (Chroococcales, Cyanobacteria), with a treatment on Gloeothece and three new genera, Crocosphaera, Rippkaea, and Zehria. JOURNAL OF PHYCOLOGY 2019; 55:578-610. [PMID: 30830691 DOI: 10.1111/jpy.12853] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/06/2018] [Indexed: 06/09/2023]
Abstract
The systematics of single-celled cyanobacteria represents a major challenge due to morphological convergence and application of various taxonomic concepts. The genus Cyanothece is one of the most problematic cases, as the name has been applied to oval-shaped coccoid cyanobacteria lacking sheaths with little regard to their phylogenetic position and details of morphology and ultrastructure. Hereby we analyze an extensive set of complementary genetic and phenotypic evidence to disentangle the relationships among these cyanobacteria. We provide diagnostic characters to separate the known genera Cyanothece, Gloeothece, and Aphanothece, and provide a valid description for Crocosphaera gen. nov. We describe two new genera, Rippkaea and Zehria, to characterize two distinct phylogenetic lineages outside the previously known genera. We further describe 13 new species in total including Cyanothece svehlovae, Gloeothece aequatorialis, G. aurea, G. bryophila, G. citriformis, G. reniformis, Gloeothece tonkinensis, G. verrucosa, Crocosphaera watsonii, C. subtropica, C. chwakensis, Rippkaea orientalis, and Zehria floridana to recognize the intrageneric diversity as rendered by polyphasic analysis. We discuss the close relationship of free-living cyanobacteria from the Crocosphaera lineage to nitrogen-fixing endosymbionts of marine algae. The current study includes several experimental strains (Crocosphaera and "Cyanothece") important for the study of diazotrophy and the global oceanic nitrogen cycle, and provides evidence suggesting ancestral N2 -fixing capability in the chroococcalean lineage.
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Affiliation(s)
- Jan Mareš
- Institute of Hydrobiology, Biology Centre, The Czech Academy of Sciences, Na Sádkách 7, CZ-37005, České Budějovice, Czech Republic
- Department of Botany, University of South Bohemia, Faculty of Science, Branišovská 1760, CZ-37005, České Budějovice, Czech Republic
| | - Jeffrey R Johansen
- Department of Botany, University of South Bohemia, Faculty of Science, Branišovská 1760, CZ-37005, České Budějovice, Czech Republic
- John Carroll University, Department of Biology, University Heights, Ohio, 44118, USA
| | - Tomáš Hauer
- Department of Botany, University of South Bohemia, Faculty of Science, Branišovská 1760, CZ-37005, České Budějovice, Czech Republic
- Institute of Botany, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-37982, Třeboň, Czech Republic
| | - Jan Zima
- Institute of Botany, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-37982, Třeboň, Czech Republic
- Department of Parasitology, Faculty of Science, University of South Bohemia, Branišovská 1760, CZ-37005, České Budějovice
| | - Stefano Ventura
- Firenze Unit, Institute of Ecosystem Study, National Research Council of Italy, via Madonna del Piano 10, I-500 19, Sesto Fiorentino, Italy
| | - Oana Cuzman
- Institute for the Conservation and Valorization of Cultural Heritage, National Research Council of Italy, via Madonna del Piano 10, I-500 19, Sesto Fiorentino, Italy
| | - Bruno Tiribilli
- Firenze Unit, Institute for Complex Systems, National Research Council of Italy, via Madonna del Piano 10, I-500 19, Sesto Fiorentino, Italy
| | - Jan Kaštovský
- Department of Botany, University of South Bohemia, Faculty of Science, Branišovská 1760, CZ-37005, České Budějovice, Czech Republic
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8
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Heath M, Wood SA, Young RG, Ryan KG. The role of nitrogen and phosphorus in regulatingPhormidiumsp. (cyanobacteria) growth and anatoxin production. FEMS Microbiol Ecol 2016; 92:fiw021. [DOI: 10.1093/femsec/fiw021] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2016] [Indexed: 01/08/2023] Open
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9
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Draft Genome Sequence of Exopolysaccharide-Producing Cyanobacterium Aphanocapsa montana BDHKU 210001. GENOME ANNOUNCEMENTS 2015; 3:3/2/e00057-15. [PMID: 25744997 PMCID: PMC4358384 DOI: 10.1128/genomea.00057-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report for the first time the draft genome sequence of Aphanocapsa montana BDHKU 210001, a halotolerant cyanobacterium isolated from India. This is a marine exopolysaccharide (EPS)-producing cyanobacterium. The genome of this species is assembled into 11.50 million bases, with 296 scaffolds carrying approximately 7,296 protein-coding genes.
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10
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Foster RA, Sztejrenszus S, Kuypers MMM. Measuring carbon and N2 fixation in field populations of colonial and free-living unicellular cyanobacteria using nanometer-scale secondary ion mass spectrometry(1). JOURNAL OF PHYCOLOGY 2013; 49:502-516. [PMID: 27007039 DOI: 10.1111/jpy.12057] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 02/05/2013] [Indexed: 06/05/2023]
Abstract
Unicellular cyanobacteria are now recognized as important to the marine N and C cycles in open ocean gyres, yet there are few direct in situ measurements of their activities. Using a high-resolution nanometer scale secondary ion mass spectrometer (nanoSIMS), single cell N2 and C fixation rates were estimated for unicellular cyanobacteria resembling N2 fixer Crocosphaera watsonii. Crocosphaera watsonii-like cells were observed in the subtropical North Pacific gyre (22°45' N, 158°0' W) as 2 different phenotypes: colonial and free-living. Colonies containing 3-242 cells per colony were observed and cell density in colonies increased with incubation time. Estimated C fixation rates were similarly high in both phenotypes and unexpectedly for unicellular cyanobacteria 85% of the colonial cells incubated during midday were also enriched in (15) N above natural abundance. Highest (15) N enrichment and N2 fixation rates were found in cells incubated overnight where up to 64% of the total daily fixed N in the upper surface waters was attributed to both phenotypes. The colonial cells retained newly fixed C in a sulfur-rich matrix surrounding the cells and often cells of both phenotypes possessed areas (<1 nm) of enriched (15) N and (13) C resembling storage granules. The nanoSIMS imaging of the colonial cells also showed evidence for a division of N2 and C fixation activity across the colony where few individual cells (<34%) in a given colony were enriched in both (15) N and (13) C above the colony average. Our results provide new insights into the ecophysiology of unicellular cyanobacteria.
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Affiliation(s)
- Rachel A Foster
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstr 1, Bremen, D-28359, Germany
| | - Saar Sztejrenszus
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstr 1, Bremen, D-28359, Germany
| | - Marcel M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstr 1, Bremen, D-28359, Germany
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11
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Bergman B, Sandh G, Lin S, Larsson J, Carpenter EJ. Trichodesmium--a widespread marine cyanobacterium with unusual nitrogen fixation properties. FEMS Microbiol Rev 2012; 37:286-302. [PMID: 22928644 PMCID: PMC3655545 DOI: 10.1111/j.1574-6976.2012.00352.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 08/13/2012] [Accepted: 08/21/2012] [Indexed: 12/03/2022] Open
Abstract
The last several decades have witnessed dramatic advances in unfolding the diversity and commonality of oceanic diazotrophs and their N2-fixing potential. More recently, substantial progress in diazotrophic cell biology has provided a wealth of information on processes and mechanisms involved. The substantial contribution by the diazotrophic cyanobacterial genus Trichodesmium to the nitrogen influx of the global marine ecosystem is by now undisputable and of paramount ecological importance, while the underlying cellular and molecular regulatory physiology has only recently started to unfold. Here, we explore and summarize current knowledge, related to the optimization of its diazotrophic capacity, from genomics to ecophysiological processes, via, for example, cellular differentiation (diazocytes) and temporal regulations, and suggest cellular research avenues that now ought to be explored.
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12
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Pereira S, Zille A, Micheletti E, Moradas-Ferreira P, De Philippis R, Tamagnini P. Complexity of cyanobacterial exopolysaccharides: composition, structures, inducing factors and putative genes involved in their biosynthesis and assembly. FEMS Microbiol Rev 2009; 33:917-41. [DOI: 10.1111/j.1574-6976.2009.00183.x] [Citation(s) in RCA: 439] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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13
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Zhao W, Ye Z, Zhao J. RbrA, a cyanobacterial rubrerythrin, functions as a FNR-dependent peroxidase in heterocysts in protection of nitrogenase from damage by hydrogen peroxide in Anabaena sp. PCC 7120. Mol Microbiol 2008; 66:1219-30. [PMID: 18001348 DOI: 10.1111/j.1365-2958.2007.05994.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The heterocyst is a specialized cell for nitrogen fixation in some filamentous cyanobacteria. Here we report that a rubrerythrin (RbrA) from Anabaena sp. PCC 7120 functions as a peroxidase in heterocysts and plays an important role in protection of nitrogenase. The electron donor for RbrA in H(2)O(2) reduction is NADPH and the electron transfer from NADPH to RbrA depends on ferredoxin:NADP(+) oxidoreductase. A rbrA mutant (r27) grew much more slowly than the wild type under diazotrophic conditions. Its nitrogenase activity measured in air was only 8% of that measured under anoxic conditions. Staining r27 filaments with 2',7'-dichlorodihydrofluorescein diacetate indicated that heterocysts had a higher H(2)O(2) concentration than the vegetative cells. The expression of rbrA was controlled by two promoters and the promoter for the smaller transcript was regulated by HetR. Spatial expression of rbrA was studied and the results showed that the transcription is localized predominantly in heterocysts. In a mutant lacking nifH and rbrA, the H(2)O(2) concentration in heterocysts was lower than that in the vegetative cells, suggesting that NifH is involved in H(2)O(2) generation. Our results demonstrate that RbrA is a critical enzyme for H(2)O(2) decomposition and provide evidence that nitrogenase autoprotection is important in heterocysts.
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Affiliation(s)
- Weixing Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing, 100871, China
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Shi T, Sun Y, Falkowski PG. Effects of iron limitation on the expression of metabolic genes in the marine cyanobacterium Trichodesmium erythraeum IMS101. Environ Microbiol 2008; 9:2945-56. [PMID: 17991025 DOI: 10.1111/j.1462-2920.2007.01406.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Iron deficiency in axenic cultures of Trichodesmium erythraeum IMS101 led to significant declines in both nitrogen fixation rates and photochemical energy conversion efficiency, accompanied by downregulation of genes encoding the major iron-binding proteins, including psbA and psbE of photosystem II, psaA and psaC of photosystem I, petB and petC of the cytochrome b(6)f complex, and nifH. However, the iron-starved cultures remained viable and expression of the metalloprotein genes was partially or fully restored within 3 days following the addition of iron. Both physiological and molecular responses revealed that expression and synthesis of the nitrogen fixation and photosynthetic machinery follow the hierarchy of iron demand; that is, nitrogen fixation was far more susceptible to iron limitation than photosynthesis. Consequently, the nifH transcript exhibited a 1-2 day shorter half-life and two to three times faster degradation rate than that of the photosynthetic genes. Our results suggest that the changes in gene expression are related to the redox state in the shared photosynthetic/respiratory pathway which, when faced with short-term iron deficiency, signals Trichodesmium to selectively sacrifice nitrogen fixation to conserve iron for photosynthetic and respiratory electron transport. The observed functional and compositional alterations represent the compromises in gene expression and acclimation capacity between two basic metabolic pathways competing for iron when it is limiting.
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Affiliation(s)
- Tuo Shi
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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15
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Tamagnini P, Leitão E, Oliveira P, Ferreira D, Pinto F, Harris DJ, Heidorn T, Lindblad P. Cyanobacterial hydrogenases: diversity, regulation and applications. FEMS Microbiol Rev 2007; 31:692-720. [PMID: 17903205 DOI: 10.1111/j.1574-6976.2007.00085.x] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Cyanobacteria may possess two distinct nickel-iron (NiFe)-hydrogenases: an uptake enzyme found in N(2)-fixing strains, and a bidirectional one present in both non-N(2)-fixing and N(2)-fixing strains. The uptake hydrogenase (encoded by hupSL) catalyzes the consumption of the H(2) produced during N(2) fixation, while the bidirectional enzyme (hoxEFUYH) probably plays a role in fermentation and/or acts as an electron valve during photosynthesis. hupSL constitute a transcriptional unit, and are essentially transcribed under N(2)-fixing conditions. The bidirectional hydrogenase consists of a hydrogenase and a diaphorase part, and the corresponding five hox genes are not always clustered or cotranscribed. The biosynthesis/maturation of NiFe-hydrogenases is highly complex, requiring several core proteins. In cyanobacteria, the genes that are thought to affect hydrogenases pleiotropically (hyp), as well as the genes presumably encoding the hydrogenase-specific endopeptidases (hupW and hoxW) have been identified and characterized. Furthermore, NtcA and LexA have been implicated in the transcriptional regulation of the uptake and the bidirectional enzyme respectively. Recently, the phylogenetic origin of cyanobacterial and algal hydrogenases was analyzed, and it was proposed that the current distribution in cyanobacteria reflects a differential loss of genes according to their ecological needs or constraints. In addition, the possibilities and challenges of cyanobacterial-based H(2) production are addressed.
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Affiliation(s)
- Paula Tamagnini
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
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16
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Staal M, Rabouille S, Stal LJ. On the role of oxygen for nitrogen fixation in the marine cyanobacterium Trichodesmium sp. Environ Microbiol 2007; 9:727-36. [PMID: 17298372 DOI: 10.1111/j.1462-2920.2006.01195.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The marine, non-heterocystous, filamentous cyanobacterium Trichodesmium shows a distinct diurnal pattern of nitrogenase activity. In an attempt to reveal the factors that control this pattern, a series of measurements were carried out using online acetylene reduction assay. Light response curves of nitrogenase were recorded applying various concentrations of oxygen. The effect of oxygen depended on the irradiance applied. Above a photon irradiance of 16 mumol m(-2) s(-1) nitrogenase activity was highest under anoxic conditions. Below this irradiance the presence of oxygen was required to achieve highest nitrogenase activity and in the dark 5% oxygen was optimal. At any oxygen concentration a photon irradiance of 100 mumol m(-2) s(-1) was saturating. When Trichodesmium was incubated in the dark, nitrogenase activity gradually decreased and this decline was higher at higher levels of oxygen. The activity recovered when the cells were subsequently incubated in the light. This recovery depended on oxygenic photosynthesis because it did not occur in the presence of DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea]. Recovery of nitrogenase activity in the light was faster at low oxygen concentrations. The results showed that under aerobic conditions nitrogenase activity was limited by the availability of reducing equivalents suggesting a competition for electrons between nitrogenase and respiration.
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Affiliation(s)
- Marc Staal
- Netherlands Institute of Ecology, NIOO-KNAW, Centre for Estuarine and Marine Ecology, P.O. Box 140, 4400 AC Yerseke, the Netherlands
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Musat F, Harder J, Widdel F. Study of nitrogen fixation in microbial communities of oil-contaminated marine sediment microcosms. Environ Microbiol 2006; 8:1834-43. [PMID: 16958764 DOI: 10.1111/j.1462-2920.2006.01069.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aerobic microbial degradation of pollutant oil (petroleum) in aquatic environments is often severely limited by the availability of combined nitrogen. We therefore studied whether the microbial community enriched in marine sediment microcosms with an added oil layer and exposure to light harboured nitrogenase activity. The acetylene reduction (AR) assay indeed indicated active nitrogenase; however, similar activity was observed in oil-free control microcosms. In both microcosms, the AR rate was significantly reduced upon a dark shift, indicating that enriched cyanobacteria were the dominant diazotrophs. Analysis of structural dinitrogenase reductase genes (nifH) amplified from both microcosms indeed revealed NifH sequences related mostly to those of heterocystous cyanobacteria. NifH sequences typically affiliating with those of heterotrophic bacteria were more frequently retrieved from the oil-containing sediment. Expression analyses showed that mainly nifH genes similar to those of heterocystous cyanobacteria were expressed in the light. Upon a dark shift, nifH genes related to those of non-heterocystous cyanobacteria were expressed. Expression of nifH assignable to heterotrophs was apparently not significant. It is concluded that cyanobacteria are the main contributors of fixed nitrogen to oil-contaminated and pristine sediments if nitrogen is a limiting factor and if light is available. Hence, also the oil-degrading heterotrophic community may thus receive a significant part of combined nitrogen from cyanobacteria, even though oil vice versa apparently does not stimulate an additional nitrogen fixation in the enriched community.
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Affiliation(s)
- Florin Musat
- Max-Planck-Institut für Marine Mikrobiologie, Celsiusstrasse 1, D-28359 Bremen, Germany
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Affiliation(s)
- Lucas J Stal
- Department of Marine Microbiology, Netherlands Institute of Ecology, P.O. Box 140, 4400 AC Yerseke, The Netherlands (tel +31 113577497; fax +31 113573616; email )
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Oelze J. Respiratory protection of nitrogenase in Azotobacter species: is a widely held hypothesis unequivocally supported by experimental evidence? FEMS Microbiol Rev 2000; 24:321-33. [PMID: 10978541 DOI: 10.1111/j.1574-6976.2000.tb00545.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The hypothesis of respiratory protection, originally formulated on the basis of results obtained with Azotobacter species, postulates that consumption of O(2) at the surface of diazotrophic prokaryotes protects nitrogenase from inactivation by O(2). Accordingly, it is assumed that, at increased ambient O(2) concentrations, nitrogenase activity depends on increased activities of a largely uncoupled respiratory electron transport system. The present review compiles evidence indicating that cellular O(2) consumption as well as both the activity and the formation of the respiratory system of Azotobacter vinelandii are controlled by the C/N ratio, that is to say the ratio at which the organism consumes the substrate (i.e. the source of carbon, reducing equivalents and ATP) per source of compound nitrogen. The maximal respiratory capacity which can be attained at increased C/N ratios, however, is controlled, within limits, by the ambient O(2) concentration. When growth becomes N-limited at increased C/N ratios, cells synthesize nitrogenase and fix N(2). Under these diazotrophic conditions, cellular O(2) consumption remains constant at a level controlled by the O(2) concentration. Control by O(2) has been studied on the basis of both whole cell respiration and defined segments of the respiratory electron transport chain. The results demonstrate that the effect of O(2) on the respiratory system is restricted to the lower range of O(2) concentrations up to about 70 microM. Nevertheless, azotobacters are able to grow diazotrophically at dissolved O(2) concentrations of up to about 230 microM indicating that respiratory protection is not warranted at increased ambient O(2) concentrations. This conclusion is supported and extended by a number of results largely excluding an obvious relationship between nitrogenase activity and the actual rate of cellular O(2) consumption. On the basis of theoretical calculations, it is assumed that the rate of O(2) diffusion into the cells is not significantly affected by respiration. All of these results lead to the conclusion that, in the protection of nitrogenase from O(2) damage, O(2) consumption at the cell surface is less effective than generally assumed. It is proposed that alternative factors like the supply of ATP and reducing equivalents are more important.
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Affiliation(s)
- J Oelze
- Universität Freiburg, Institut für Biologie II (Mikrobiologie), Schänzlestr. 1, D-79104, Freiburg, Germany.
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Abstract
It is generally considered that nitrogen availability is one of the major factors regulating primary production in temperate coastal marine environments. Coastal regions often receive large anthropogenic inputs of nitrogen that cause eutrophication. The impact of these nitrogen additions has a profound effect in estuaries and coastal lagoons where water exchange is limited. Such increased nutrient loading promotes the growth of phytoplankton and fast growing pelagic macroalgae while rooted plants (sea-grasses) and benthic are suppressed due to reduced light availability. This shift from benthic to pelagic primary production introduces large diurnal variations in oxygen concentrations in the water column. In addition oxygen consumption in the surface sediments increases due to the deposition of readily degradable biomass. In this review the physico-chemical and biological factors regulating nitrogen cycling in coastal marine ecosystems are considered in relation to developing effective management programmes to rehabilitate seagrass communities in lagoons currently dominated by pelagic macroalgae and/or cyanobacteria.
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Affiliation(s)
- R A Herbert
- Department of Biological Sciences, University of Dundee, Dundee, UK
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