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Brentjens ET, Beall EAK, Zucker RM. Analysis of Microcystis aeruginosa physiology by spectral flow cytometry: Impact of chemical and light exposure. PLOS WATER 2023; 2:1-30. [PMID: 38516272 PMCID: PMC10953801 DOI: 10.1371/journal.pwat.0000177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
M. aeruginosa fluorescent changes were observed using a Cytek Aurora spectral flow cytometer that contains 5 lasers and 64 narrow band detectors located between 365 and 829 nm. Cyanobacteria were treated with different concentrations of H2O2 and then monitored after exposure between 1 and 8 days. The red fluorescence emission derived from the excitation of cyanobacteria with a yellow green laser (550 nm) was measured in the 652-669 nm detector while green fluorescence from excitation with a violet laser (405 nm) was measured in the 532-550 nm detector. The changes in these parameters were measured after the addition of H2O2. There was an initial increase in red fluorescence intensity at 24 hours. This was followed by a daily decrease in red fluorescence intensity. In contrast, green fluorescence increased at 24 hours and remained higher than the control for the duration of the 8-day study. A similar fluorescence intensity effect as H2O2 on M. aeruginosa fluorescence emissions was observed after exposure to acetylacetone, diuron (DCMU), peracetic acid, and tryptoline. Minimal growth was also observed in H2O2 treated cyanobacteria during exposure of H2O2 for 24 days. In another experiment, H2O2-treated cyanobacteria were exposed to high-intensity blue (14 mW) and UV (1 mW) lights to assess the effects of light stress on fluorescence emissions. The combination of blue and UV light with H2O2 had a synergistic effect on M. aeruginosa that induced greater fluorescent differences between control and treated samples than exposure to either stimulus individually. These experiments suggest that the early increase in red and green fluorescence may be due to an inhibition in the ability of photosynthesis to process photons. Further research into the mechanisms driving these increases in fluorescence is necessary.
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Affiliation(s)
- Emma T. Brentjens
- Oak Ridge Institute for Science and Education Research Participation Program hosted by U.S. Environmental Protection Agency, Oak Ridge, TN, United States of America
| | - Elizabeth A. K. Beall
- Oak Ridge Institute for Science and Education Research Participation Program hosted by U.S. Environmental Protection Agency, Oak Ridge, TN, United States of America
| | - Robert M. Zucker
- Public Health and Integrated Toxicology Division, Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Office of Research and Development, RTP, NC, United States of America
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2
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Ortega-Martínez P, Roldán M, Díaz-Troya S, Florencio FJ. Stress response requires an efficient connection between glycogen and central carbon metabolism by phosphoglucomutases in cyanobacteria. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:1532-1550. [PMID: 36454663 PMCID: PMC10010611 DOI: 10.1093/jxb/erac474] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Glycogen and starch are the main storage polysaccharides, acting as a source of carbon and energy when necessary. Interconversion of glucose-1-phosphate and glucose-6-phosphate by phosphoglucomutases connects the metabolism of these polysaccharides with central carbon metabolism. However, knowledge about how this connection affects the ability of cells to cope with environmental stresses is still scarce. The cyanobacterium Synechocystis sp. PCC 6803 has two enzymes with phosphoglucomutase activity, PGM (phosphoglucomutase) and PMM/PGM (phosphomannomutase/phosphoglucomutase). In this work, we generated a null mutant of PGM (∆PGM) that exhibits very reduced phosphoglucomutase activity (1% of wild type activity). Although this mutant accumulates moderate amounts of glycogen, its phenotype resembles that of glycogen-less mutants, including high light sensitivity and altered response to nitrogen deprivation. Using an on/off arsenite promoter, we demonstrate that PMM/PGM is essential for growth and responsible for the remaining phosphoglucomutase activity in the ∆PGM strain. Furthermore, overexpression of PMM/PGM in the ∆PGM strain is enough to revoke the phenotype of this mutant. These results emphasize the importance of an adequate flux between glycogen and central carbon metabolism to maintain cellular fitness and indicate that although PGM is the main phosphoglucomutase activity, the phosphoglucomutase activity of PMM/PGM can substitute it when expressed in sufficient amounts.
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Affiliation(s)
- Pablo Ortega-Martínez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Américo Vespucio 49, Sevilla, 41092, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Profesor García González s/n, Sevilla, 41012, Spain
| | - Miguel Roldán
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Profesor García González s/n, Sevilla, 41012, Spain
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3
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Chiang YH, Huang YJ, Fu HY. Identification of multiple nonphotochemical quenching processes in the extremophilic red alga Cyanidioschyzon merolae. PHOTOSYNTHESIS RESEARCH 2022; 154:125-141. [PMID: 36155877 DOI: 10.1007/s11120-022-00963-2] [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: 05/30/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Nonphotochemical quenching acts as a frontline response to prevent excitation energy from reaching the photochemical reaction center of photosystem II before photodamage occurs. Strong fluorescence quenching after merely one multi-turnover saturating light pulse characterizes a unique feature of nonphotochemical quenching in red algae. Several mechanisms underlying red algal nonphotochemical quenching have been proposed, yet which process(es) dominantly account for the strong fluorescence quenching is still under discussion. Here we assessed multiple nonphotochemical quenching processes in the extremophilic red alga Cyanidioschyzon merolae under light pulse and continuous illumination conditions. To assess the nonphotochemical quenching processes that might display different kinetics, fluorescence emission spectra at 77 K were measured after different periods of light treatments, and external fluorophores were added for normalization of the fluorescence level. The phycobilisome- and photosystem II-related nonphotochemical quenching processes were distinguished by light preferentially absorbed by phycobilisomes and photosystems, respectively. Multiple nonphotochemical quenching processes, including the energetic decoupling of phycobilisomes from photosystem II, the energy spillover from phycobilisomes to photosystem I and from photosystem II to photosystem I, were identified along with the previously identified intrinsic quenching within photosystem II. The ability to use multiple nonphotochemical quenching processes appears to maximize the light harvesting efficiency for photochemistry and to provide the flexibility of the energy redistribution between photosystem II and photosystem I. The effect of the various ionophores on the nonphotochemical quenching level suggests that nonphotochemical quenching is modulated by transmembrane gradients of protons and other cations.
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Affiliation(s)
- Yu-Hao Chiang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Yu-Jia Huang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Han-Yi Fu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan.
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4
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Squires A, Wang Q, Dahlberg P, Moerner WE. A bottom-up perspective on photodynamics and photoprotection in light-harvesting complexes using anti-Brownian trapping. J Chem Phys 2022; 156:070901. [DOI: 10.1063/5.0079042] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Quan Wang
- Genomics, Princeton University, United States of America
| | | | - W. E. Moerner
- Department of Chemistry, Stanford University, United States of America
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5
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Selim KA, Haffner M, Burkhardt M, Mantovani O, Neumann N, Albrecht R, Seifert R, Krüger L, Stülke J, Hartmann MD, Hagemann M, Forchhammer K. Diurnal metabolic control in cyanobacteria requires perception of second messenger signaling molecule c-di-AMP by the carbon control protein SbtB. SCIENCE ADVANCES 2021; 7:eabk0568. [PMID: 34878830 PMCID: PMC8654305 DOI: 10.1126/sciadv.abk0568] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Because of their photosynthesis-dependent lifestyle, cyanobacteria evolved sophisticated regulatory mechanisms to adapt to oscillating day-night metabolic changes. How they coordinate the metabolic switch between autotrophic and glycogen-catabolic metabolism in light and darkness is poorly understood. Recently, c-di-AMP has been implicated in diurnal regulation, but its mode of action remains elusive. To unravel the signaling functions of c-di-AMP in cyanobacteria, we isolated c-di-AMP receptor proteins. Thereby, the carbon-sensor protein SbtB was identified as a major c-di-AMP receptor, which we confirmed biochemically and by x-ray crystallography. In search for the c-di-AMP signaling function of SbtB, we found that both SbtB and c-di-AMP cyclase–deficient mutants showed reduced diurnal growth and that c-di-AMP–bound SbtB interacts specifically with the glycogen-branching enzyme GlgB. Accordingly, both mutants displayed impaired glycogen synthesis during the day and impaired nighttime survival. Thus, the pivotal role of c-di-AMP in day-night acclimation can be attributed to SbtB-mediated regulation of glycogen metabolism.
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Affiliation(s)
- Khaled A. Selim
- Organismic Interactions Department, Interfaculty Institute for Microbiology and Infection Medicine, Cluster of Excellence ‘Controlling Microbes to Fight Infections’, Tübingen University, Auf der Morgenstelle 28, 72076 Tübingen, Germany
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
- Corresponding author. (K.A.S.); (K.F.)
| | - Michael Haffner
- Organismic Interactions Department, Interfaculty Institute for Microbiology and Infection Medicine, Cluster of Excellence ‘Controlling Microbes to Fight Infections’, Tübingen University, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Markus Burkhardt
- Organismic Interactions Department, Interfaculty Institute for Microbiology and Infection Medicine, Cluster of Excellence ‘Controlling Microbes to Fight Infections’, Tübingen University, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Oliver Mantovani
- Plant Physiology Department, Institute of Biological Sciences, Rostock University, Rostock, Germany
| | - Niels Neumann
- Organismic Interactions Department, Interfaculty Institute for Microbiology and Infection Medicine, Cluster of Excellence ‘Controlling Microbes to Fight Infections’, Tübingen University, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Reinhard Albrecht
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Roland Seifert
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany
| | - Larissa Krüger
- Department of General Microbiology, Göttingen Center for Molecular Biosciences (GZMB), Göttingen University, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Göttingen Center for Molecular Biosciences (GZMB), Göttingen University, Göttingen, Germany
| | - Marcus D. Hartmann
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Martin Hagemann
- Plant Physiology Department, Institute of Biological Sciences, Rostock University, Rostock, Germany
| | - Karl Forchhammer
- Organismic Interactions Department, Interfaculty Institute for Microbiology and Infection Medicine, Cluster of Excellence ‘Controlling Microbes to Fight Infections’, Tübingen University, Auf der Morgenstelle 28, 72076 Tübingen, Germany
- Corresponding author. (K.A.S.); (K.F.)
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6
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State of the phycobilisome determines effective absorption cross-section of Photosystem II in Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148494. [PMID: 34534546 DOI: 10.1016/j.bbabio.2021.148494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/23/2021] [Accepted: 09/07/2021] [Indexed: 11/23/2022]
Abstract
Quenching of excess excitation energy is necessary for the photoprotection of light-harvesting complexes. In cyanobacteria, quenching of phycobilisome (PBS) excitation energy is induced by the Orange Carotenoid Protein (OCP), which becomes photoactivated under high light conditions. A decrease in energy transfer efficiency from the PBSs to the reaction centers decreases photosystem II (PS II) activity. However, quantitative analysis of OCP-induced photoprotection in vivo is complicated by similar effects of both photochemical and non-photochemical quenching on the quantum yield of the PBS fluorescence overlapping with the emission of chlorophyll. In the present study, we have analyzed chlorophyll a fluorescence induction to estimate the effective cross-section of PS II and compared the effects of reversible OCP-dependent quenching of PBS fluorescence with reduction of PBS content upon nitrogen starvation or mutations of key PBS components. This approach allowed us to estimate the dependency of the rate constant of PS II primary electron acceptor reduction on the amount of PBSs in the cell. We found that OCP-dependent quenching triggered by blue light affects approximately half of PBSs coupled to PS II, indicating that under normal conditions, the concentration of OCP is not sufficient for quenching of all PBSs coupled to PS II.
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7
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Bolychevtseva YV, Tropin IV, Stadnichuk IN. State 1 and State 2 in Photosynthetic Apparatus of Red Microalgae and Cyanobacteria. BIOCHEMISTRY. BIOKHIMIIA 2021; 86:1181-1191. [PMID: 34903149 DOI: 10.1134/s0006297921100023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/23/2021] [Accepted: 06/23/2021] [Indexed: 06/14/2023]
Abstract
Imbalanced light absorption by photosystem I (PSI) and photosystem II (PSII) in oxygenic phototrophs leads to changes in interaction of photosystems altering the linear electron flow. In plants and green algae, this imbalance is mitigated by a partial migration of the chlorophyll a/b containing light-harvesting antenna between the two photosystem core complexes. This migration is registered as fluorescence changes of the pigment apparatus and is termed the reverse transitions between States 1 and 2. By contrast, the molecular mechanism of State 1/2 transitions in phycobilisome (PBS)-containing photosynthetics, cyanobacteria and red algae, is still insufficiently understood. The suggested hypotheses - PBS movement along the surface of thylakoid membrane between PSI and PSII complexes, reversible PBS detachment from the dimeric PSII complex, and spillover - have some limitations as they do not fully explain the accumulated data. Here, we have recorded changes in the stationary fluorescence emission spectra of red algae and cyanobacteria in States 1/2 at room temperature, which allowed us to offer an explanation of the existing contradictions. The change of room temperature fluorescence of chlorophyll belonged to PSII was revealed, while the fluorescence of PBS associated with the PSII complexes remained during States 1/2 transitions at the stable level. Only the reversible dissociation of PBS from the monomeric PSI was revealed earlier which implied different degree of surface contact of PBS with the two photosystems. The detachment of PBS from the PSI corresponds to ferredoxin oxidation as electron carrier and the increase of cyclic electron transport in the pigment apparatus in State I.
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Affiliation(s)
- Yulia V Bolychevtseva
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
| | - Ivan V Tropin
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Igor N Stadnichuk
- Timiryasev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127726, Russia.
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8
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Meier DV, Greve AJ, Chennu A, van Erk MR, Muthukrishnan T, Abed RMM, Woebken D, de Beer D. Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat. Appl Environ Microbiol 2021; 87:e0069821. [PMID: 34160273 PMCID: PMC8357274 DOI: 10.1128/aem.00698-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/16/2021] [Indexed: 12/18/2022] Open
Abstract
Hypersaline microbial mats are dense microbial ecosystems capable of performing complete element cycling and are considered analogs of early Earth and hypothetical extraterrestrial ecosystems. We studied the functionality and limits of key biogeochemical processes, such as photosynthesis, aerobic respiration, and sulfur cycling, in salt crust-covered microbial mats from a tidal flat at the coast of Oman. We measured light, oxygen, and sulfide microprofiles as well as sulfate reduction rates at salt saturation and in flood conditions and determined fine-scale stratification of pigments, biomass, and microbial taxa in the resident microbial community. The salt crust did not protect the mats against irradiation or evaporation. Although some oxygen production was measurable at salinities of ≤30% (wt/vol) in situ, at saturation-level salinity (40%), oxygenic photosynthesis was completely inhibited and only resumed 2 days after reducing the porewater salinity to 12%. Aerobic respiration and active sulfur cycling occurred at low rates under salt saturation and increased strongly upon salinity reduction. Apart from high relative abundances of Chloroflexi, photoheterotrophic Alphaproteobacteria, Bacteroidetes, and Archaea, the mat contained a distinct layer harboring filamentous Cyanobacteria, which is unusual for such high salinities. Our results show that the diverse microbial community inhabiting this salt flat mat ultimately depends on periodic salt dilution to be self-sustaining and is rather adapted to merely survive salt saturation than to thrive under the salt crust. IMPORTANCE Due to their abilities to survive intense radiation and low water availability, hypersaline microbial mats are often suggested to be analogs of potential extraterrestrial life. However, even the limitations imposed on microbial processes by saturation-level salinity found on Earth have rarely been studied in situ. While abundance and diversity of microbial life in salt-saturated environments are well documented, most of our knowledge on process limitations stems from culture-based studies, few in situ studies, and theoretical calculations. In particular, oxygenic photosynthesis has barely been explored beyond 5 M NaCl (28% wt/vol). By applying a variety of biogeochemical and molecular methods, we show that despite abundance of photoautotrophic microorganisms, oxygenic photosynthesis is inhibited in salt-crust-covered microbial mats at saturation salinities, while rates of other energy generation processes are decreased several-fold. Hence, the complete element cycling required for self-sustaining microbial communities only occurs at lower salt concentrations.
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Affiliation(s)
- Dimitri V. Meier
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | | | - Arjun Chennu
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- Leibniz Centre for Tropical Marine Research, Bremen, Germany
| | | | | | - Raeid M. M. Abed
- Biology Department, College of Science, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Dagmar Woebken
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Bremen, Germany
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9
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Photosynthetic monitoring techniques indicate maximum glycogen accumulation in nitrogen-limited Synechocystis sp. PCC 6803 culture. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Gwizdala M, Lebre PH, Maggs-Kölling G, Marais E, Cowan DA, Krüger TPJ. Sub-lithic photosynthesis in hot desert habitats. Environ Microbiol 2021; 23:3867-3880. [PMID: 33817951 DOI: 10.1111/1462-2920.15505] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/03/2021] [Indexed: 11/26/2022]
Abstract
In hyper-arid soil environments, photosynthetic microorganisms are largely restricted to hypolithic (sub-lithic) habitats: i.e., on the ventral surfaces of translucent pebbles in desert pavements. Here, we combined fluorometric, spectroscopic, biochemical and metagenomic approaches to investigate in situ the light transmission properties of quartz stones in the Namib Desert, and assess the photosynthetic activity of the underlying hypolithic cyanobacterial biofilms. Quartz pebbles greatly reduced the total photon flux to the ventral surface biofilms and filtered out primarily the short wavelength portion of the solar spectrum. Chlorophylls d and f were not detected in biofilm pigment extracts; however, hypolithic cyanobacterial communities showed some evidence of adaptation to sub-lithic conditions, including the prevalence of genes encoding Helical Carotenoid Proteins, which are associated with desiccation stress. Under water-saturated conditions, hypolithic communities showed no evidence of light stress, even when the quartz stones were exposed to full midday sunlight. This initial study creates a foundation for future in-situ and laboratory exploration of various adaptation mechanisms employed by photosynthetic organisms forming hypolithic microbial communities.
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Affiliation(s)
- Michal Gwizdala
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.,Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | | | - Eugene Marais
- Gobabeb-Namib Research Institute, Walvis Bay, Namibia
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Tjaart P J Krüger
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.,Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
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11
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Dark adaptation and ability of pulse-amplitude modulated (PAM) fluorometry to identify nutrient limitation in the bloom-forming cyanobacterium, Microcystis aeruginosa (Kützing). JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 219:112186. [PMID: 33892284 DOI: 10.1016/j.jphotobiol.2021.112186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 03/30/2021] [Accepted: 04/03/2021] [Indexed: 11/21/2022]
Abstract
Harmful algal blooms in inland waters are widely linked to excess phosphorus (P) loading, but increasing evidence shows that their growth and formation can also be influenced by nitrogen (N) and iron (Fe). Deficiency in N, P, and Fe differentially affects cellular photosystems and is manifested as changes in photosynthetic yield (Fv/Fm). While Fv/Fm has been increasingly used as a rapid and convenient in situ gauge of nutrient deficiency, there are few rigorous comparisons of instrument sensitivity and ability to resolve specific nutrient stresses. This study evaluated the application of Fv/Fm to cyanobacteria using controlled experiments on a single isolate and tested three hypotheses: i) single Fv/Fm measurements taken with different PAM fluorometers can distinguish among limitation by different nutrients, ii) measurements of Fv/Fm made by the addition of DCMU are comparable to PAM fluorometers, and iii) dark adaptation is not necessary for reliable Fv/Fm measurements. We compared Fv/Fm taken from the bloom-forming Microcystis aeruginosa (UTEX LB 3037) grown in nutrient-replete treatment (R) and N-, P-, and Fe-limited treatments (LN, LP, LFe, respectively), using three pulse-amplitude modulated (PAM) fluorometers and the chemical photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and evaluated the effects of dark adaptation prior to PAM measurement. There were significant differences in Fv/Fm estimates among PAM fluorometers for light- versus dark-adapted cell suspensions over the whole experiment (21 days), which were all significantly higher than the DCMU-based measurements. However, dark adaptation had no effect on Fv/Fm when comparing PAM-based values across a single nutrient treatment. All Fv/Fm methods could distinguish LN and LP from R and LFe treatments but none were able to resolve LFe from R, or LN from LP cultures. These results indicated that for most PAM applications, dark adaptation is not necessary, and furthermore that single measurements of Fv/Fm do not provide a robust measurement of nutrient limitation in Microcystis aeruginosa UTEX LB 3037, and potentially other, common freshwater cyanobacteria.
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12
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Xu K, Li Z, Juneau P, Xiao F, Lian Y, Zhang W, Shu L, Jiang H, Zhang K, Wang C, Wang S, Yan Q, He Z. Toxic and protective mechanisms of cyanobacterium Synechocystis sp. in response to titanium dioxide nanoparticles. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 274:116508. [PMID: 33516953 DOI: 10.1016/j.envpol.2021.116508] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 01/09/2021] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
An increasing production and use of titanium dioxide nanoparticles (TiO2 NPs) pose a huge threat to phytoplankton since they are largely released into aquatic environments, which represent a sink for TiO2 NPs. However, toxicity and protective mechanisms of cyanobacteria in response to TiO2 NPs remain elusive. Here we investigated toxic effects of two sizes of TiO2 NPs (50 and 10 nm) and one bulk TiO2 (200 nm) on a cyanobacterium, Synechocystis sp. and their possible protective mechanisms. We found that 10 nm TiO2 NPs caused significant growth and photosynthesis inhibition in Synechocystis sp. cells, largely reflected in decreased growth rate (38%), operational PSII quantum yields (40%), phycocyanin (51%) and allophycocyanin (63%), and increased reactive oxygen species content (245%), superoxide dismutase activity (46%). Also, transcriptomic analysis of Synechocystis sp. exposure to 10 nm TiO2 NPs showed the up-regulation of D1 and D2 protein genes (psbA and psbD), ferredoxin gene (petF) and F-type ATPase genes (e.g., atpB), and the down-regulation of psbM and psb28-2 in PS II. We further proposed a conceptual model to explore possible toxic and protective mechanisms for Synechocystis sp. under TiO2 nanoparticle exposure. This study provides mechanistic insights into our understanding of Synechocystis sp. responses to TiO2 NPs. This is essential for more accurate environmental risk assessment approaches of nanoparticles in aquatic ecosystems by governmental environmental agencies worldwide.
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Affiliation(s)
- Kui Xu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Zhou Li
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Philippe Juneau
- Department of Biological Sciences, GRIL - EcotoQ - TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Université Du Québec à Montréal, Succursale Centre-Ville, Montreal, Quebec, Canada
| | - Fanshu Xiao
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Yingli Lian
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Wei Zhang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Longfei Shu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Haibo Jiang
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China; School of Life Sciences, Central China Normal University, Wuhan, 430079, Hubei, China
| | - Keke Zhang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Cheng Wang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China; South China Sea Institution, Sun Yat-sen University, Zhuhai, 519082, China
| | - Shanquan Wang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Qingyun Yan
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China
| | - Zhili He
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, Guangdong, China; College of Agronomy, Hunan Agricultural University, Changsha, 410128, Hunan, China.
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Bernát G, Zavřel T, Kotabová E, Kovács L, Steinbach G, Vörös L, Prášil O, Somogyi B, Tóth VR. Photomorphogenesis in the Picocyanobacterium Cyanobium gracile Includes Increased Phycobilisome Abundance Under Blue Light, Phycobilisome Decoupling Under Near Far-Red Light, and Wavelength-Specific Photoprotective Strategies. FRONTIERS IN PLANT SCIENCE 2021; 12:612302. [PMID: 33815434 PMCID: PMC8012758 DOI: 10.3389/fpls.2021.612302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Photomorphogenesis is a process by which photosynthetic organisms perceive external light parameters, including light quality (color), and adjust cellular metabolism, growth rates and other parameters, in order to survive in a changing light environment. In this study we comprehensively explored the light color acclimation of Cyanobium gracile, a common cyanobacterium in turbid freshwater shallow lakes, using nine different monochromatic growth lights covering the whole visible spectrum from 435 to 687 nm. According to incident light wavelength, C. gracile cells performed great plasticity in terms of pigment composition, antenna size, and photosystem stoichiometry, to optimize their photosynthetic performance and to redox poise their intersystem electron transport chain. In spite of such compensatory strategies, C. gracile, like other cyanobacteria, uses blue and near far-red light less efficiently than orange or red light, which involves moderate growth rates, reduced cell volumes and lower electron transport rates. Unfavorable light conditions, where neither chlorophyll nor phycobilisomes absorb light sufficiently, are compensated by an enhanced antenna size. Increasing the wavelength of the growth light is accompanied by increasing photosystem II to photosystem I ratios, which involve better light utilization in the red spectral region. This is surprisingly accompanied by a partial excitonic antenna decoupling, which was the highest in the cells grown under 687 nm light. So far, a similar phenomenon is known to be induced only by strong light; here we demonstrate that under certain physiological conditions such decoupling is also possible to be induced by weak light. This suggests that suboptimal photosynthetic performance of the near far-red light grown C. gracile cells is due to a solid redox- and/or signal-imbalance, which leads to the activation of this short-term light acclimation process. Using a variety of photo-biophysical methods, we also demonstrate that under blue wavelengths, excessive light is quenched through orange carotenoid protein mediated non-photochemical quenching, whereas under orange/red wavelengths state transitions are involved in photoprotection.
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Affiliation(s)
- Gábor Bernát
- Balaton Limnological Institute, Centre for Ecological Research, Tihany, Hungary
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Tomáš Zavřel
- Global Change Research Institute, Academy of Sciences of the Czech Republic, Brno, Czechia
| | - Eva Kotabová
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Gábor Steinbach
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
- Cellular Imaging Laboratory, Biological Research Center, Eötvös Loránd Research Network, Szeged, Hungary
| | - Lajos Vörös
- Balaton Limnological Institute, Centre for Ecological Research, Tihany, Hungary
| | - Ondřej Prášil
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Boglárka Somogyi
- Balaton Limnological Institute, Centre for Ecological Research, Tihany, Hungary
| | - Viktor R. Tóth
- Balaton Limnological Institute, Centre for Ecological Research, Tihany, Hungary
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14
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Sma-Air S, Ritchie RJ. Spectrofluorometric Insights into the Application of PAM Fluorometry in Photosynthetic Research. Photochem Photobiol 2021; 97:991-1000. [PMID: 33704805 DOI: 10.1111/php.13413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/22/2021] [Accepted: 03/08/2021] [Indexed: 11/29/2022]
Abstract
Although pulse amplitude modulation (PAM) fluorometry has revolutionized photosynthetic studies, Photosynthetic Electron Transport Rate (ETR) cannot be measured using PAM technology in some organisms. We compare in vivo absorbance information on a selection of photosynthetic organisms using an integrating sphere spectrophotometry on a variety of oxygenic and nonoxygenic photo-organisms and provide fluorescence data to help in understanding why PAM technology is unsuccessful on some organisms, particularly cyanobacteria. The study includes anoxygenic photosynthetic bacteria: Afifella marina, Rhodopseudomonas palustris and Thermochromatium which are all RC-2 type photosynthetic bacteria (Bacteriochlorophyll a or BChl a) which are known to have measureable delayed fluorescence, Yield and hence measureable ETR. The common unicellular green alga, Chlorella sp (Chl a + b) uses the same primary photosynthetic pigments as vascular plants. Comparisons are made to some other representative oxygenic unicellular organisms: Trebouxia (Chlorophyta, Chl a + b), Chaetoceros (a diatom, Chl a + c1 c2 ) and the unusual cyanobacterium Acaryochloris marina which has Chl d + a but uses Chl d as its primary photosynthetic pigment. Synechococcus R-2 (Cyanobacteria) has only Chl a. Its fluorescence is outside the range normally used for measuring photosynthesis using PAM technology: delayed fluorescence is not readily detectable.
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Affiliation(s)
- Suhailar Sma-Air
- ANED (Andaman Environment and Natural Disaster Research Centre), Faculty of Technology and Environment, Prince of Songkla University-Phuket, Phuket, Thailand
| | - Raymond J Ritchie
- ANED (Andaman Environment and Natural Disaster Research Centre), Faculty of Technology and Environment, Prince of Songkla University-Phuket, Phuket, Thailand
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15
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Bhatti AF, Choubeh RR, Kirilovsky D, Wientjes E, van Amerongen H. State transitions in cyanobacteria studied with picosecond fluorescence at room temperature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148255. [PMID: 32619427 DOI: 10.1016/j.bbabio.2020.148255] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/19/2020] [Accepted: 06/21/2020] [Indexed: 11/30/2022]
Abstract
Cyanobacteria can rapidly regulate the relative activity of their photosynthetic complexes photosystem I and II (PSI and PSII) in response to changes in the illumination conditions. This process is known as state transitions. If PSI is preferentially excited, they go to state I whereas state II is induced either after preferential excitation of PSII or after dark adaptation. Different underlying mechanisms have been proposed in literature, in particular i) reversible shuttling of the external antenna complexes, the phycobilisomes, between PSI and PSII, ii) reversible spillover of excitation energy from PSII to PSI, iii) a combination of both and, iv) increased excited-state quenching of the PSII core in state II. Here we investigated wild-type and mutant strains of Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 using time-resolved fluorescence spectroscopy at room temperature. Our observations support model iv, meaning that increased excited-state quenching of the PSII core occurs in state II thereby balancing the photochemistry of photosystems I and II.
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Affiliation(s)
- Ahmad Farhan Bhatti
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands
| | | | - Diana Kirilovsky
- Institute for Integrative Biology of the Cell (12BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands; MicroSpectroscopy Research Facility, Wageningen University, Wageningen, the Netherlands.
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16
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Santabarbara S, Villafiorita Monteleone F, Remelli W, Rizzo F, Menin B, Casazza AP. Comparative excitation-emission dependence of the F V /F M ratio in model green algae and cyanobacterial strains. PHYSIOLOGIA PLANTARUM 2019; 166:351-364. [PMID: 30693538 DOI: 10.1111/ppl.12931] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 05/16/2023]
Abstract
The emission spectra collected under conditions of open (F0 ) and closed (FM ) photosystem II (PSII) reaction centres are close-to-independent from the excitation wavelength in Chlamydomonas reinhardtii and Chlorella sorokiniana, whereas a pronounced dependence is observed in Synechocystis sp. PCC6803 and Synechococcus PCC7942, instead. The differences in band-shape between the F0 and FM emission are limited in green algae, giving rise only to a minor trough in the FV /FM spectrum in the 705-720 nm range, irrespectively of the excitation. More substantial variations are observed in cyanobacteria, resulting in marked dependencies of the measured FV /FM ratios on both the excitation and the detection wavelengths. In cyanobacteria, the maximal FV /FM values (0.5-0.7), observed monitoring at approximately 684 nm and exciting Chl a preferentially, are comparable to those of green algae; however, FV /FM decreases sharply below approximately 660 nm. Furthermore, in the red emission tail, the trough in the FV /FM spectrum is more pronounced in cyanobacteria with respect to green algae, corresponding to FV /FM values of 0.25-0.4 in this spectral region. Upon direct phycobilisomes excitation (i.e. >520 nm), the FV /FM value detected at 684 nm decreases to 0.3-0.5 and is close-to-negligible (approximately 0.1) below 660 nm. At the same time, the FV spectra are, in all species investigated, almost independent on the excitation wavelength. It is concluded that the excitation/emission dependencies of the FV /FM ratio arise from overlapped contributions from the three independent emissions of PSI, PSII and a fraction of energetically uncoupled external antenna, excited in different proportions depending on the respective optical cross-section and fluorescence yield.
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Affiliation(s)
- Stefano Santabarbara
- Centre for Fundamental Research in Photosynthesis, 21029, Vergiate, Italy
- Photosynthesis Research Unit, Centro Studi sulla Biologia Cellulare e Molecolare delle Piante, 20133, Milan, Italy
| | | | - William Remelli
- Centre for Fundamental Research in Photosynthesis, 21029, Vergiate, Italy
| | - Federico Rizzo
- Centre for Fundamental Research in Photosynthesis, 21029, Vergiate, Italy
| | - Barbara Menin
- Photosynthesis Research Unit, Centro Studi sulla Biologia Cellulare e Molecolare delle Piante, 20133, Milan, Italy
| | - Anna Paola Casazza
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, 20133, Milan, Italy
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A novel Ca 2+-binding protein influences photosynthetic electron transport in Anabaena sp. PCC 7120. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:519-532. [PMID: 31034800 DOI: 10.1016/j.bbabio.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/17/2019] [Accepted: 04/23/2019] [Indexed: 12/25/2022]
Abstract
Ca2+ is a potent signalling molecule that regulates many cellular processes. In cyanobacteria, Ca2+ has been linked to cell growth, stress response and photosynthesis, and to the development of specialist heterocyst cells in certain nitrogen-fixing species. Despite this, the pathways of Ca2+ signal transduction in cyanobacteria are poorly understood, and very few protein components are known. The current study describes a previously unreported Ca2+-binding protein which was called the Ca2+ Sensor EF-hand (CSE), which is conserved in filamentous, nitrogen-fixing cyanobacteria. CSE is shown to bind Ca2+, which induces a conformational change in the protein structure. Poor growth of a strain of Anabaena sp. PCC 7120 overexpressing CSE was attributed to diminished photosynthetic performance. Transcriptomics, biophysics and proteomics analyses revealed modifications in the light-harvesting phycobilisome and photosynthetic reaction centre protein complexes.
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18
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Grund M, Jakob T, Wilhelm C, Bühler B, Schmid A. Electron balancing under different sink conditions reveals positive effects on photon efficiency and metabolic activity of Synechocystis sp. PCC 6803. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:43. [PMID: 30858880 PMCID: PMC6391784 DOI: 10.1186/s13068-019-1378-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/14/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND Cyanobacteria are ideal model organisms to exploit photosynthetically derived electrons or fixed carbon for the biotechnological synthesis of high value compounds and energy carriers. Much effort is spent on the rational design of heterologous pathways to produce value-added chemicals. Much less focus is drawn on the basic physiological responses and potentials of phototrophs to deal with natural or artificial electron and carbon sinks. However, an understanding of how electron sinks influence or regulate cellular physiology is essential for the efficient application of phototrophic organisms in an industrial setting, i.e., to achieve high productivities and product yields. RESULTS The physiological responses of the cyanobacterium Synechocystis sp. PCC 6803 to electron sink variation were investigated in a systematic and quantitative manner. A variation in electron demand was achieved by providing two N sources with different degrees of reduction. By additionally varying light and CO2 availabilities, steady state conditions with strongly differing source-sink ratios were established. Balancing absorbed photons and electrons used for different metabolic processes revealed physiological responses to sink/source ratio variation. Surprisingly, an additional electron sink under light and thus energy limitation was found not to hamper growth, but was compensated by improved photosynthetic efficiency and activity. In the absence of carbon and light limitation, an increase in electron demand even stimulated carbon assimilation and growth. CONCLUSION The metabolism of Synechocystis sp. PCC 6803 is highly flexible regarding the compensation of additional electron demands. Under light limitation, photosynthesis obviously does not necessarily run at its maximal capacity, possibly for the sake of robustness. Increased electron demands can even boost photosynthetic activity and growth.
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Affiliation(s)
- Marcel Grund
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Torsten Jakob
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Christian Wilhelm
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Bruno Bühler
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Andreas Schmid
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
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Remelli W, Santabarbara S. Excitation and emission wavelength dependence of fluorescence spectra in whole cells of the cyanobacterium Synechocystis sp. PPC6803: Influence on the estimation of Photosystem II maximal quantum efficiency. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:1207-1222. [PMID: 30297025 DOI: 10.1016/j.bbabio.2018.09.366] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/13/2018] [Accepted: 09/17/2018] [Indexed: 11/20/2022]
Abstract
The fluorescence emission spectrum of Synechocystis sp. PPC6803 cells, at room temperature, displays: i) significant bandshape variations when collected under open (F0) and closed (FM) Photosystem II reaction centre conditions; ii) a marked dependence on the excitation wavelength both under F0 and FM conditions, due to the enhancement of phycobilisomes (PBS) emission upon their direct excitation. As a consequence: iii) the ratio of the variable and maximal fluorescence (FV/FM), that is a commonly employed indicator of the maximal photochemical quantum efficiency of PSII (Φpc, PSII), displays a significant dependency on both the excitation and the emission (detection) wavelength; iv) the FV/FM excitation/emission wavelength dependency is due, primarily, to the overlap of PSII emission with that of supercomplexes showing negligible changes in quantum yield upon trap closure, i.e. PSI and a PBS fraction which is incapable to transfer the excitation energy efficiently to core complexes. v) The contribution to the cellular emission and the relative absorption-cross section of PSII, PSI and uncoupled PBS are extracted using a spectral decomposition strategy. It is concluded that vi) Φpc, PSII is generally underestimated from the FV/FM measurements in this organism and, the degree of the estimation bias, which can exceed 50%, depends on the measurement conditions. Spectral modelling based on the decomposed emission/cross-section profiles were extended to other processes typically monitored from steady-state fluorescence measurements, in the presence of an actinic illumination, in particular non-photochemical quenching. It is suggested that vii) the quenching extent is generally underestimated in analogy to FV/FM but that viii) the location of quenching sites can be discriminated based on the combined excitation/emission spectral analysis.
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Affiliation(s)
- William Remelli
- Photosynthesis Research Unit, Centro Studi sulla Biologia Cellulare e Molecolare delle Piante, 20133 Milano, Italy
| | - Stefano Santabarbara
- Photosynthesis Research Unit, Centro Studi sulla Biologia Cellulare e Molecolare delle Piante, 20133 Milano, Italy.
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20
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Spät P, Klotz A, Rexroth S, Maček B, Forchhammer K. Chlorosis as a Developmental Program in Cyanobacteria: The Proteomic Fundament for Survival and Awakening. Mol Cell Proteomics 2018; 17:1650-1669. [PMID: 29848780 DOI: 10.1074/mcp.ra118.000699] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/25/2018] [Indexed: 11/06/2022] Open
Abstract
Cyanobacteria that do not fix atmospheric nitrogen gas survive prolonged periods of nitrogen starvation in a chlorotic, dormant state where cell growth and metabolism are arrested. Upon nutrient availability, these dormant cells return to vegetative growth within 2-3 days. This resuscitation process is highly orchestrated and relies on the stepwise reinstallation and activation of essential cellular structures and functions. We have been investigating the transition to chlorosis and the return to vegetative growth as a simple model of a cellular developmental process and a fundamental survival strategy in biology. In the present study, we used quantitative proteomics and phosphoproteomics to describe the proteomic landscape of a dormant cyanobacterium and its dynamics during the transition to vegetative growth. We identified intriguing alterations in the set of ribosomal proteins, in RuBisCO components, in the abundance of central regulators and predicted metabolic enzymes. We found O-phosphorylation as an abundant protein modification in the chlorotic state, specifically of metabolic enzymes and proteins involved in photosynthesis. Nondegraded phycobiliproteins were hyperphosphorylated in the chlorotic state. We provide evidence that hyperphosphorylation of the terminal rod linker CpcD increases the lifespan of phycobiliproteins during chlorosis.
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Affiliation(s)
- Philipp Spät
- From the ‡Interfaculty Institute for Microbiology and Infection Medicine, Eberhard-Karls University Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.,¶Proteome Center Tuebingen, Eberhard-Karls-University Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Alexander Klotz
- From the ‡Interfaculty Institute for Microbiology and Infection Medicine, Eberhard-Karls University Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Sascha Rexroth
- §Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Boris Maček
- ¶Proteome Center Tuebingen, Eberhard-Karls-University Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Karl Forchhammer
- From the ‡Interfaculty Institute for Microbiology and Infection Medicine, Eberhard-Karls University Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany;
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21
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Ogawa T, Misumi M, Sonoike K. Estimation of photosynthesis in cyanobacteria by pulse-amplitude modulation chlorophyll fluorescence: problems and solutions. PHOTOSYNTHESIS RESEARCH 2017; 133:63-73. [PMID: 28283890 DOI: 10.1007/s11120-017-0367-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 03/02/2017] [Indexed: 05/09/2023]
Abstract
Cyanobacteria are photosynthetic prokaryotes and widely used for photosynthetic research as model organisms. Partly due to their prokaryotic nature, however, estimation of photosynthesis by chlorophyll fluorescence measurements is sometimes problematic in cyanobacteria. For example, plastoquinone pool is reduced in the dark-acclimated samples in many cyanobacterial species so that conventional protocol developed for land plants cannot be directly applied for cyanobacteria. Even for the estimation of the simplest chlorophyll fluorescence parameter, F v/F m, some additional protocol such as addition of DCMU or illumination of weak blue light is necessary. In this review, those problems in the measurements of chlorophyll fluorescence in cyanobacteria are introduced, and solutions to those problems are given.
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Affiliation(s)
- Takako Ogawa
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, 162-8480, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Masahiro Misumi
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, 162-8480, Japan
| | - Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, 162-8480, Japan.
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22
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Kerfeld CA, Melnicki MR, Sutter M, Dominguez-Martin MA. Structure, function and evolution of the cyanobacterial orange carotenoid protein and its homologs. THE NEW PHYTOLOGIST 2017; 215:937-951. [PMID: 28675536 DOI: 10.1111/nph.14670] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
Contents 937 I. 937 II. 938 III. 939 IV. 943 V. 947 VI. 948 948 References 949 SUMMARY: The orange carotenoid protein (OCP) is a water-soluble, photoactive protein involved in thermal dissipation of excess energy absorbed by the light-harvesting phycobilisomes (PBS) in cyanobacteria. The OCP is structurally and functionally modular, consisting of a sensor domain, an effector domain and a keto-carotenoid. On photoactivation, the OCP converts from a stable orange form, OCPO , to a red form, OCPR . Activation is accompanied by a translocation of the carotenoid deeper into the effector domain. The increasing availability of cyanobacterial genomes has enabled the identification of new OCP families (OCP1, OCP2, OCPX). The fluorescence recovery protein (FRP) detaches OCP1 from the PBS core, accelerating its back-conversion to OCPO ; by contrast, other OCP families are not regulated by FRP. N-terminal domain homologs, the helical carotenoid proteins (HCPs), have been found among diverse cyanobacteria, occurring as multiple paralogous groups, with two representatives exhibiting strong singlet oxygen (1 O2 ) quenching (HCP2, HCP3) and another capable of dissipating PBS excitation (HCP4). Crystal structures are presently available for OCP1 and HCP1, and models of other HCP subtypes can be readily produced as a result of strong sequence conservation, providing new insights into the determinants of carotenoid binding and 1 O2 quenching.
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Affiliation(s)
- Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Matthew R Melnicki
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Markus Sutter
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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23
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Ruan Z, Raven JA, Giordano M. In Synechococcus sp. competition for energy between assimilation and acquisition of C and those of N only occurs when growth is light limited. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3829-3839. [PMID: 28369501 DOI: 10.1093/jxb/erx074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The carbon-concentrating mechanisms (CCMs) of cyanobacteria counteract the low CO2 affinity and CO2:O2 selectivities of the Rubisco of these photolithotrophs and the relatively low oceanic CO2 availability. CCMs have a significant energy cost; if light is limiting, the use of N sources whose assimilation demands less energy could permit a greater investment of energy into CCMs and inorganic C (Ci) assimilation. To test this, we cultured Synechococcus sp. UTEX LB 2380 under either N or energy limitation, in the presence of NO3- or NH4+. When growth was energy-limited, NH4+-grown cells had a 1.2-fold higher growth rate, 1.3-fold higher dissolved inorganic carbon (DIC)-saturated photosynthetic rate, 19% higher linear electron transfer, 80% higher photosynthetic 1/K1/2(DIC), 2.0-fold greater slope of the linear part of the photosynthesis versus DIC curve, 3.5-fold larger intracellular Ci pool, and 2.3-fold higher Zn quota than NO3--grown cells. When energy was not limiting growth, there were not differences between NH4+- and NO3--grown cells, except for higher linear electron transfer and larger intracellular Ci pool.We conclude that, when energy limits growth, cells that use the cheaper N source divert energy from N assimilation to C acquisition and assimilation; this does not happen when energy is not limiting.
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Affiliation(s)
- Zuoxi Ruan
- Marine Biology Institute, Science Center, Shantou University, Shantou, Guangdong 515063, China
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona 60131, Italy
| | - John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Ultimo NSW 2007, Australia
| | - Mario Giordano
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona 60131, Italy
- Institute of Microbiology ASCR, Algatech, Trebon, Czech Republic
- National Research Council, Institute of Marine Science, Venezia, Italy
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24
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Bersanini L, Allahverdiyeva Y, Battchikova N, Heinz S, Lespinasse M, Ruohisto E, Mustila H, Nickelsen J, Vass I, Aro EM. Dissecting the Photoprotective Mechanism Encoded by the flv4-2 Operon: a Distinct Contribution of Sll0218 in Photosystem II Stabilization. PLANT, CELL & ENVIRONMENT 2017; 40:378-389. [PMID: 27928824 DOI: 10.1111/pce.12872] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/17/2016] [Accepted: 11/20/2016] [Indexed: 06/06/2023]
Abstract
In Synechocystis sp. PCC 6803, the flv4-2 operon encodes the flavodiiron proteins Flv2 and Flv4 together with a small protein, Sll0218, providing photoprotection for Photosystem II (PSII). Here, the distinct roles of Flv2/Flv4 and Sll0218 were addressed, using a number of flv4-2 operon mutants. In the ∆sll0218 mutant, the presence of Flv2/Flv4 rescued PSII functionality as compared with ∆sll0218-flv2, where neither Sll0218 nor the Flv2/Flv4 heterodimer are expressed. Nevertheless, both the ∆sll0218 and ∆sll0218-flv2 mutants demonstrated deficiency in accumulation of PSII proteins suggesting a role for Sll0218 in PSII stabilization, which was further supported by photoinhibition experiments. Moreover, the accumulation of PSII assembly intermediates occurred in Sll0218-lacking mutants. The YFP-tagged Sll0218 protein localized in a few spots per cell at the external side of the thylakoid membrane, and biochemical membrane fractionation revealed clear enrichment of Sll0218 in the PratA-defined membranes, where the early biogenesis steps of PSII occur. Further, the characteristic antenna uncoupling feature of the ∆flv4-2 operon mutants is shown to be related to PSII destabilization in the absence of Sll0218. It is concluded that the Flv2/Flv4 heterodimer supports PSII functionality, while the Sll0218 protein assists PSII assembly and stabilization, including optimization of light harvesting.
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Affiliation(s)
- Luca Bersanini
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Yagut Allahverdiyeva
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Natalia Battchikova
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Steffen Heinz
- Molecular Plant Sciences, Ludwig-Maximillians-Universität München, Biozentrum, Grosshaderner Straße 2-4, 82152, Planegg-Martinsried, Germany
| | - Maija Lespinasse
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Essi Ruohisto
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Henna Mustila
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
| | - Jörg Nickelsen
- Molecular Plant Sciences, Ludwig-Maximillians-Universität München, Biozentrum, Grosshaderner Straße 2-4, 82152, Planegg-Martinsried, Germany
| | - Imre Vass
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, P.O. Box 521, H-6701, Szeged, Hungary
| | - Eva-Mari Aro
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland
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Westermark S, Steuer R. Toward Multiscale Models of Cyanobacterial Growth: A Modular Approach. Front Bioeng Biotechnol 2016; 4:95. [PMID: 28083530 PMCID: PMC5183639 DOI: 10.3389/fbioe.2016.00095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 12/09/2016] [Indexed: 11/29/2022] Open
Abstract
Oxygenic photosynthesis dominates global primary productivity ever since its evolution more than three billion years ago. While many aspects of phototrophic growth are well understood, it remains a considerable challenge to elucidate the manifold dependencies and interconnections between the diverse cellular processes that together facilitate the synthesis of new cells. Phototrophic growth involves the coordinated action of several layers of cellular functioning, ranging from the photosynthetic light reactions and the electron transport chain, to carbon-concentrating mechanisms and the assimilation of inorganic carbon. It requires the synthesis of new building blocks by cellular metabolism, protection against excessive light, as well as diurnal regulation by a circadian clock and the orchestration of gene expression and cell division. Computational modeling allows us to quantitatively describe these cellular functions and processes relevant for phototrophic growth. As yet, however, computational models are mostly confined to the inner workings of individual cellular processes, rather than describing the manifold interactions between them in the context of a living cell. Using cyanobacteria as model organisms, this contribution seeks to summarize existing computational models that are relevant to describe phototrophic growth and seeks to outline their interactions and dependencies. Our ultimate aim is to understand cellular functioning and growth as the outcome of a coordinated operation of diverse yet interconnected cellular processes.
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Affiliation(s)
- Stefanie Westermark
- Fachinstitut für Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin , Berlin , Germany
| | - Ralf Steuer
- Fachinstitut für Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin , Berlin , Germany
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Schuurmans RM, van Alphen P, Schuurmans JM, Matthijs HCP, Hellingwerf KJ. Comparison of the Photosynthetic Yield of Cyanobacteria and Green Algae: Different Methods Give Different Answers. PLoS One 2015; 10:e0139061. [PMID: 26394153 PMCID: PMC4578884 DOI: 10.1371/journal.pone.0139061] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/07/2015] [Indexed: 11/18/2022] Open
Abstract
The societal importance of renewable carbon-based commodities and energy carriers has elicited a particular interest for high performance phototrophic microorganisms. Selection of optimal strains is often based on direct comparison under laboratory conditions of maximal growth rate or additional valued features such as lipid content. Instead of reporting growth rate in culture, estimation of photosynthetic efficiency (quantum yield of PSII) by pulse-amplitude modulated (PAM) fluorimetry is an often applied alternative method. Here we compared the quantum yield of PSII and the photonic yield on biomass for the green alga Chlorella sorokiniana 211-8K and the cyanobacterium Synechocystis sp. PCC 6803. Our data demonstrate that the PAM technique inherently underestimates the photosynthetic efficiency of cyanobacteria by rendering a high F0 and a low FM, specifically after the commonly practiced dark pre-incubation before a yield measurement. Yet when comparing the calculated biomass yield on light in continuous culture experiments, we obtained nearly equal values for both species. Using mutants of Synechocystis sp. PCC 6803, we analyzed the factors that compromise its PAM-based quantum yield measurements. We will discuss the role of dark respiratory activity, fluorescence emission from the phycobilisomes, and the Mehler-like reaction. Based on the above observations we recommend that PAM measurements in cyanobacteria are interpreted only qualitatively.
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Affiliation(s)
- R. Milou Schuurmans
- Molecular Microbial Physiology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Pascal van Alphen
- Molecular Microbial Physiology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - J. Merijn Schuurmans
- Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Hans C. P. Matthijs
- Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Klaas J. Hellingwerf
- Molecular Microbial Physiology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Photanol BV, Amsterdam, The Netherlands
- * E-mail:
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