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Special Issue "Compounds from Cyanobacteria"

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A special issue of Marine Drugs (ISSN 1660-3397).

Deadline for manuscript submissions: closed (30 September 2015)

Special Issue Editor

Guest Editor
Assoc. Prof. Michele R. Prinsep

Department of Chemistry, The University of Waikato, Te Whare Wānanga o Waikato, Gate 1 Knighton Road, Private Bag 3105, Hamilton 3240, New Zealand
Website | E-Mail
Interests: natural products chemistry; application of spectral methods to structural determination; biologically active compounds and structure-activity relationships; chemical ecology

Special Issue Information

Dear Colleagues,

Cyanobacteria (blue-green algae) are an ancient and successful group of organisms that are found in a wide range of marine and freshwater habitats and in conditions as extreme as the heat of volcanic regions to the cold of Antarctica. They have proven to be an excellent source of secondary metabolites, many of which possess biological activity. The most common class of compounds found in cyanobacteria are oligopeptides (predominantly cyclic peptides). These are synthesised by nonribosomal peptide synthetases and many contain unique or unusual amino acids. Some of the other compound classes that have been isolated from cyanobacteria include terpenes and alkaloids.
Many of the natural products produced by cyanobacteria may be ecologically significant and some of the toxic metabolites are a human health concern, especially when present in recreational water bodies or fisheries. Cyanobacteria often have the means to produce many more metabolites than are actually expressed, so an understanding of biosynthesis and genetics in these organisms is vitally important.
There is considerable overlap between metabolites produced by terrestrial and marine cyanobacteria, hence the scope of this issue has been widened to include compounds from freshwater cyanobacteria, in addition to studies of marine species.

Dr. Michele R. Prinsep
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).

Keywords

  • Cyanobacteria
  • blue-green algae
  • algal bloom
  • oligopeptides
  • amino acids
  • non-ribosomal peptide synthesis
  • biological activity
  • biosynthesis
  • secondary metabolites

Published Papers (25 papers)

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Research

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Open AccessArticle Comparison of Protein Phosphatase Inhibition Assay with LC-MS/MS for Diagnosis of Microcystin Toxicosis in Veterinary Cases
Mar. Drugs 2016, 14(3), 54; doi:10.3390/md14030054
Received: 29 September 2015 / Revised: 29 February 2016 / Accepted: 3 March 2016 / Published: 9 March 2016
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Abstract
Microcystins are acute hepatotoxins of increasing global concern in drinking and recreational waters and are a major health risk to humans and animals. Produced by cyanobacteria, microcystins inhibit serine/threonine protein phosphatase 1 (PP1). A cost-effective PP1 assay using p-nitrophenyl phosphate was developed
[...] Read more.
Microcystins are acute hepatotoxins of increasing global concern in drinking and recreational waters and are a major health risk to humans and animals. Produced by cyanobacteria, microcystins inhibit serine/threonine protein phosphatase 1 (PP1). A cost-effective PP1 assay using p-nitrophenyl phosphate was developed to quickly assess water and rumen content samples. Significant inhibition was determined via a linear model, which compared increasing volumes of sample to the log-transformed ratio of the exposed rate over the control rate of PP1 activity. To test the usefulness of this model in diagnostic case investigations, samples from two veterinary cases were tested. In August 2013 fifteen cattle died around two ponds in Kentucky. While one pond and three tested rumen contents had significant PP1 inhibition and detectable levels of microcystin-LR, the other pond did not. In August 2013, a dog became fatally ill after swimming in Clear Lake, California. Lake water samples collected one and four weeks after the dog presented with clinical signs inhibited PP1 activity. Subsequent analysis using liquid chromatography-mass spectrometry (LC-MS/MS) detected microcystin congeners -LR, -LA, -RR and -LF but not -YR. These diagnostic investigations illustrate the advantages of using functional assays in combination with LC-MS/MS. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Effects of Halide Ions on the Carbamidocyclophane Biosynthesis in Nostoc sp. CAVN2
Mar. Drugs 2016, 14(1), 21; doi:10.3390/md14010021
Received: 15 October 2015 / Revised: 9 December 2015 / Accepted: 21 December 2015 / Published: 20 January 2016
Cited by 2 | PDF Full-text (3529 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, the influence of halide ions on [7.7]paracyclophane biosynthesis in the cyanobacterium Nostoc sp. CAVN2 was investigated. In contrast to KI and KF, supplementation of the culture medium with KCl or KBr resulted not only in an increase of growth but
[...] Read more.
In this study, the influence of halide ions on [7.7]paracyclophane biosynthesis in the cyanobacterium Nostoc sp. CAVN2 was investigated. In contrast to KI and KF, supplementation of the culture medium with KCl or KBr resulted not only in an increase of growth but also in an up-regulation of carbamidocyclophane production. LC-MS analysis indicated the presence of chlorinated, brominated, but also non-halogenated derivatives. In addition to 22 known cylindrocyclophanes and carbamidocyclophanes, 27 putative congeners have been detected. Nine compounds, carbamidocyclophanes M−U, were isolated, and their structural elucidation by 1D and 2D NMR experiments in combination with HRMS and ECD analysis revealed that they are brominated analogues of chlorinated carbamidocyclophanes. Quantification of the carbamidocyclophanes showed that chloride is the preferably utilized halide, but incorporation is reduced in the presence of bromide. Evaluation of the antibacterial activity of 30 [7.7]paracyclophanes and related derivatives against selected pathogenic Gram-positive and Gram-negative bacteria exhibited remarkable effects especially against methicillin- and vancomycin-resistant staphylococci and Mycobacterium tuberculosis. For deeper insights into the mechanisms of biosynthesis, the carbamidocyclophane biosynthetic gene cluster in Nostoc sp. CAVN2 was studied. The gene putatively coding for the carbamoyltransferase has been identified. Based on bioinformatic analyses, a possible biosynthetic assembly is discussed. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Structures and Activity of New Anabaenopeptins Produced by Baltic Sea Cyanobacteria
Mar. Drugs 2016, 14(1), 8; doi:10.3390/md14010008
Received: 22 October 2015 / Revised: 22 December 2015 / Accepted: 23 December 2015 / Published: 30 December 2015
Cited by 4 | PDF Full-text (1544 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Anabaenopeptins, bioactive cyclic hexapeptides, were isolated by preparative reversed-phase high performance liquid chromatography from an extract of Baltic Sea cyanobacterial bloom material composed of Nodularia spumigena (50%), Aphanizomenon flos-aquae (40%) and Dolichospermum spp. (10%). Five new anabaenopeptins and nine previously known anabaenopeptins were
[...] Read more.
Anabaenopeptins, bioactive cyclic hexapeptides, were isolated by preparative reversed-phase high performance liquid chromatography from an extract of Baltic Sea cyanobacterial bloom material composed of Nodularia spumigena (50%), Aphanizomenon flos-aquae (40%) and Dolichospermum spp. (10%). Five new anabaenopeptins and nine previously known anabaenopeptins were isolated, and their putative structures were determined by tandem mass spectrometry. The activity of the peptides against carboxypeptidase A and protein phosphatase 1 as well as chymotrypsin, trypsin and thrombin was tested. All anabaenopeptins inhibited carboxypeptidase A (apart from one anabaenopeptin variant) and protein phosphatase 1 with varying potency, but no inhibition against chymotrypsin, trypsin and thrombin was observed. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Isolation and Synthesis of Laxaphycin B-Type Peptides: A Case Study and Clues to Their Biosynthesis
Mar. Drugs 2015, 13(12), 7285-7300; doi:10.3390/md13127065
Received: 15 October 2015 / Accepted: 30 November 2015 / Published: 5 December 2015
PDF Full-text (644 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The laxaphyci’s B family constitutes a group of five related cyclic lipopeptides isolated from diverse cyanobacteria from all around the world. This group shares a typical structure of 12 amino acids from the l and d series, some of them hydroxylated at the
[...] Read more.
The laxaphyci’s B family constitutes a group of five related cyclic lipopeptides isolated from diverse cyanobacteria from all around the world. This group shares a typical structure of 12 amino acids from the l and d series, some of them hydroxylated at the beta position, and all containing a rare beta-amino decanoic acid. Nevertheless, they can be differentiated due to slight variations in the composition of their amino acids, but the configuration of their alpha carbon remains conserved. Here, we provide the synthesis and characterization of new laxaphycin B-type peptides. In doing so we discuss how the synthesis of laxaphycin B and analogues was developed. We also isolate minor acyclic laxaphycins B, which are considered clues to their biosynthesis. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Seasonal Changes in Mycosporine-Like Amino Acid Production Rate with Respect to Natural Phytoplankton Species Composition
Mar. Drugs 2015, 13(11), 6740-6758; doi:10.3390/md13116740
Received: 2 September 2015 / Revised: 1 October 2015 / Accepted: 7 October 2015 / Published: 6 November 2015
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Abstract
After in situ incubation at the site for a year, phytoplanktons in surface water were exposed to natural light in temperate lakes (every month); thereafter, the net production rate of photoprotective compounds (mycosporine-like amino acids, MAAs) was calculated using 13C labeled tracer.
[...] Read more.
After in situ incubation at the site for a year, phytoplanktons in surface water were exposed to natural light in temperate lakes (every month); thereafter, the net production rate of photoprotective compounds (mycosporine-like amino acids, MAAs) was calculated using 13C labeled tracer. This is the first report describing seasonal variation in the net production rate of individual MAAs in temperate lakes using a compound-specific stable isotope method. In the mid-latitude region of the Korean Peninsula, UV radiation (UVR) usually peaks from July to August. In Lake Paldang and Lake Cheongpyeong, diatoms dominated among the phytoplankton throughout the year. The relative abundance of Cyanophyceae (Anabaena spiroides) reached over 80% during July in Lake Cheongpyeong. Changes in phytoplankton abundance indicate that the phytoplankton community structure is influenced by seasonal changes in the net production rate and concentration of MAAs. Notably, particulate organic matter (POM) showed a remarkable change based on the UV intensity occurring during that period; this was because of the fact that cyanobacteria that are highly sensitive to UV irradiance dominated the community. POM cultured in Lake Paldang had the greatest shinorine (SH) production rate during October, i.e., 83.83 ± 10.47 fgC·L−1·h−1. The dominance of diatoms indicated that they had a long-term response to UVR. Evaluation of POM cultured in Lake Cheongpyeong revealed that there was an increase in the net MAA production in July (when UVR reached the maximum); a substantial amount of SH, i.e., 17.62 ± 18.34 fgC·L−1·h−1, was recorded during this period. Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure. In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae). Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?
Mar. Drugs 2015, 13(11), 6703-6722; doi:10.3390/md13116703
Received: 30 August 2015 / Revised: 20 October 2015 / Accepted: 26 October 2015 / Published: 30 October 2015
Cited by 1 | PDF Full-text (1071 KB) | HTML Full-text | XML Full-text
Abstract
Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic
[...] Read more.
Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Cyanobacterial Toxic and Bioactive Peptides in Freshwater Bodies of Greece: Concentrations, Occurrence Patterns, and Implications for Human Health
Mar. Drugs 2015, 13(10), 6319-6335; doi:10.3390/md13106319
Received: 7 August 2015 / Revised: 29 September 2015 / Accepted: 29 September 2015 / Published: 12 October 2015
Cited by 3 | PDF Full-text (840 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanobacterial harmful algal blooms represent one of the most conspicuous waterborne microbial hazards in aquatic environments mostly due to the production of toxic secondary metabolites, mainly microcystins (MCs). Other bioactive peptides are frequently found in cyanobacterial blooms, yet their concentration and ecological relevance
[...] Read more.
Cyanobacterial harmful algal blooms represent one of the most conspicuous waterborne microbial hazards in aquatic environments mostly due to the production of toxic secondary metabolites, mainly microcystins (MCs). Other bioactive peptides are frequently found in cyanobacterial blooms, yet their concentration and ecological relevance is still unknown. In this paper we studied the presence and concentration of cyanobacterial peptides (microcystins, anabaenopeptins, anabaenopeptilides) in 36 Greek freshwater bodies, using HPLC-DAD, ELISA, and PP1IA. Microcystins were found in more than 90% of the samples investigated, indicating that microcystin-producing strains seem to also occur in lakes without blooms. Microcystins MC-RR, MC-LR, and MC-YR were the main toxin constituents of the bloom samples. Anabaenopeptin A and B were predominant in some samples, whereas anabaenopeptolide 90A was the only peptide found in Lake Mikri Prespa. The intracellular concentrations of anabaenopeptins produced by cyanobacterial bloom populations are determined for the first time in this study; the high (>1000 µg·L−1) anabaenopeptin concentration found indicates there may be some impacts, at least on the ecology and the food web structure of the aquatic ecosystems. The maximum intracellular MC values measured in Lakes Kastoria and Pamvotis, exceeding 10,000 µg·L−1, are among the highest reported. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle γ-Lindane Increases Microcystin Synthesis in Microcystis aeruginosa PCC7806
Mar. Drugs 2015, 13(9), 5666-5680; doi:10.3390/md13095666
Received: 2 July 2015 / Revised: 20 July 2015 / Accepted: 29 July 2015 / Published: 3 September 2015
Cited by 1 | PDF Full-text (635 KB) | HTML Full-text | XML Full-text
Abstract
HCH factories, and the waste dumpsites associated to its production, have become a global environmental concern, and their runoff could pollute ground and surface waters with high levels of the pollutant. In this study, the influence of lindane (γ-HCH) on microcystin production has
[...] Read more.
HCH factories, and the waste dumpsites associated to its production, have become a global environmental concern, and their runoff could pollute ground and surface waters with high levels of the pollutant. In this study, the influence of lindane (γ-HCH) on microcystin production has been investigated in Microcystis aeruginosa PCC7806. This toxic cyanobacterium is highly tolerant to γ-lindane (20 mg/L), and produces more toxin (microcystin) in the presence of the pollutant. Microcystis degrades γ-lindane and presence of γ-lindane induces genes involved in its own degradation (nirA). RT-PCRsq has been used to monitor changes in levels of transcripts encoded by the mcy operon (mcyD, mcyH and mcyJ), responsible for the microcystin synthesis machinery, as well as other genes involved in its transcriptional regulation, such as ntcA and fur family members. The presence of lindane in the culture media induces mcyD expression, as well as ntcA gene transcription, while other genes, such as mcyH, (putative ABC transporter), are downregulated. The amount of microcystin found in the cells and the culture media is higher when M. aeruginosa is treated with γ-lindane than in control cells. The results suggest that in a lindane polluted environment, Microcystis toxic strains may enhance their microcystin synthesis. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle Structural Characterization of New Peptide Variants Produced by Cyanobacteria from the Brazilian Atlantic Coastal Forest Using Liquid Chromatography Coupled to Quadrupole Time-of-Flight Tandem Mass Spectrometry
Mar. Drugs 2015, 13(6), 3892-3919; doi:10.3390/md13063892
Received: 26 February 2015 / Revised: 14 May 2015 / Accepted: 21 May 2015 / Published: 18 June 2015
Cited by 2 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by
[...] Read more.
Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins) were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp.). Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Anti-Chikungunya Viral Activities of Aplysiatoxin-Related Compounds from the Marine Cyanobacterium Trichodesmium erythraeum
Mar. Drugs 2014, 12(1), 115-127; doi:10.3390/md12010115
Received: 14 October 2013 / Revised: 25 November 2013 / Accepted: 12 December 2013 / Published: 3 January 2014
Cited by 12 | PDF Full-text (738 KB) | HTML Full-text | XML Full-text
Abstract
Tropical filamentous marine cyanobacteria have emerged as a viable source of novel bioactive natural products for drug discovery and development. In the present study, aplysiatoxin (1), debromoaplysiatoxin (2) and anhydrodebromoaplysiatoxin (3), as well as two new analogues,
[...] Read more.
Tropical filamentous marine cyanobacteria have emerged as a viable source of novel bioactive natural products for drug discovery and development. In the present study, aplysiatoxin (1), debromoaplysiatoxin (2) and anhydrodebromoaplysiatoxin (3), as well as two new analogues, 3-methoxyaplysiatoxin (4) and 3-methoxydebromoaplysiatoxin (5), are reported for the first time from the marine cyanobacterium Trichodesmium erythraeum. The identification of the bloom-forming cyanobacterial strain was confirmed based on phylogenetic analysis of its 16S rRNA sequences. Structural determination of the new analogues was achieved by extensive NMR spectroscopic analysis and comparison with NMR spectral data of known compounds. In addition, the antiviral activities of these marine toxins were assessed using Chikungunya virus (CHIKV)-infected cells. Post-treatment experiments using the debrominated analogues, namely compounds 2, 3 and 5, displayed dose-dependent inhibition of CHIKV when tested at concentrations ranging from 0.1 µM to 10.0 µM. Furthermore, debromoaplysiatoxin (2) and 3-methoxydebromoaplysiatoxin (5) exhibited significant anti-CHIKV activities with EC50 values of 1.3 μM and 2.7 μM, respectively, and selectivity indices of 10.9 and 9.2, respectively. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle N-Terminal Protease Gene Phylogeny Reveals the Potential for Novel Cyanobactin Diversity in Cyanobacteria
Mar. Drugs 2013, 11(12), 4902-4916; doi:10.3390/md11124902
Received: 13 October 2013 / Revised: 21 November 2013 / Accepted: 21 November 2013 / Published: 9 December 2013
Cited by 5 | PDF Full-text (959 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanobactins are a recently recognized group of ribosomal cyclic peptides produced by cyanobacteria, which have been studied because of their interesting biological activities. Here, we have used a PCR-based approach to detect the N-terminal protease (A) gene from cyanobactin synthetase gene clusters,
[...] Read more.
Cyanobactins are a recently recognized group of ribosomal cyclic peptides produced by cyanobacteria, which have been studied because of their interesting biological activities. Here, we have used a PCR-based approach to detect the N-terminal protease (A) gene from cyanobactin synthetase gene clusters, in a set of diverse cyanobacteria from our culture collection (Laboratory of Ecotoxicology, Genomics and Evolution (LEGE) CC). Homologues of this gene were found in Microcystis and Rivularia strains, and for the first time in Cuspidothrix, Phormidium and Sphaerospermopsis strains. Phylogenetic relationships inferred from available A-gene sequences, including those obtained in this work, revealed two new groups of phylotypes, harboring Phormidium, Sphaerospermopsis and Rivularia LEGE isolates. Thus, this study shows that, using underexplored cyanobacterial strains, it is still possible to expand the known genetic diversity of genes involved in cyanobactin biosynthesis. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle Glycosylated Porphyra-334 and Palythine-Threonine from the Terrestrial Cyanobacterium Nostoc commune
Mar. Drugs 2013, 11(9), 3124-3154; doi:10.3390/md11093124
Received: 20 June 2013 / Revised: 19 July 2013 / Accepted: 29 July 2013 / Published: 26 August 2013
Cited by 8 | PDF Full-text (1088 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Mycosporine-like amino acids (MAAs) are water-soluble UV-absorbing pigments, and structurally different MAAs have been identified in eukaryotic algae and cyanobacteria. In this study novel glycosylated MAAs were found in the terrestrial cyanobacterium Nostoc commune (N. commune). An MAA with an absorption
[...] Read more.
Mycosporine-like amino acids (MAAs) are water-soluble UV-absorbing pigments, and structurally different MAAs have been identified in eukaryotic algae and cyanobacteria. In this study novel glycosylated MAAs were found in the terrestrial cyanobacterium Nostoc commune (N. commune). An MAA with an absorption maximum at 334 nm was identified as a hexose-bound porphyra-334 derivative with a molecular mass of 508 Da. Another MAA with an absorption maximum at 322 nm was identified as a two hexose-bound palythine-threonine derivative with a molecular mass of 612 Da. These purified MAAs have radical scavenging activities in vitro, which suggests multifunctional roles as sunscreens and antioxidants. The 612-Da MAA accounted for approximately 60% of the total MAAs and contributed approximately 20% of the total radical scavenging activities in a water extract, indicating that it is the major water-soluble UV-protectant and radical scavenger component. The hexose-bound porphyra-334 derivative and the glycosylated palythine-threonine derivatives were found in a specific genotype of N. commune, suggesting that glycosylated MAA patterns could be a chemotaxonomic marker for the characterization of the morphologically indistinguishable N. commune. The glycosylation of porphyra-334 and palythine-threonine in N. commune suggests a unique adaptation for terrestrial environments that are drastically fluctuating in comparison to stable aquatic environments. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle Double Strand Breaks and Cell-Cycle Arrest Induced by the Cyanobacterial Toxin Cylindrospermopsin in HepG2 Cells
Mar. Drugs 2013, 11(8), 3077-3090; doi:10.3390/md11083077
Received: 27 June 2013 / Revised: 23 July 2013 / Accepted: 31 July 2013 / Published: 21 August 2013
Cited by 12 | PDF Full-text (696 KB) | HTML Full-text | XML Full-text
Abstract
The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the
[...] Read more.
The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1–0.5 µg/mL, 24–96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120
Mar. Drugs 2013, 11(8), 3091-3108; doi:10.3390/md11083091
Received: 1 May 2013 / Revised: 21 June 2013 / Accepted: 31 July 2013 / Published: 21 August 2013
Cited by 10 | PDF Full-text (985 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the
[...] Read more.
Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle Bouillonamide: A Mixed Polyketide–Peptide Cytotoxin from the Marine Cyanobacterium Moorea bouillonii
Mar. Drugs 2013, 11(8), 3015-3024; doi:10.3390/md11083015
Received: 16 May 2013 / Revised: 10 July 2013 / Accepted: 30 July 2013 / Published: 19 August 2013
Cited by 4 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The tropical marine cyanobacterium, Moorea bouillonii, has gained recent attention as a rich source of bioactive natural products. Continued chemical investigation of this cyanobacterium, collected from New Britain, Papua New Guinea, yielded a novel cytotoxic cyclic depsipeptide, bouillonamide (1), along
[...] Read more.
The tropical marine cyanobacterium, Moorea bouillonii, has gained recent attention as a rich source of bioactive natural products. Continued chemical investigation of this cyanobacterium, collected from New Britain, Papua New Guinea, yielded a novel cytotoxic cyclic depsipeptide, bouillonamide (1), along with previously reported molecules, ulongamide A and apratoxin A. Planar structure of bouillonamide was established by extensive 1D and 2D NMR experiments, including multi-edited HSQC, TOCSY, HBMC, and ROESY experiments. In addition to the presence of α-amino acid residues, compound 1 contained two unique polyketide-derived moieties, namely a 2-methyl-6-methylamino-hex-5-enoic acid (Mmaha) residue and a unit of 3-methyl-5-hydroxy-heptanoic acid (Mhha). Absolute stereochemistry of the α-amino acid units in bouillonamide was determined mainly by Marfey’s analysis. Compound 1 exhibited mild toxicity with IC50’s of 6.0 µM against the neuron 2a mouse neuroblastoma cells. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Growth and Saxitoxin Production by Cylindrospermopsis raciborskii (Cyanobacteria) Correlate with Water Hardness
Mar. Drugs 2013, 11(8), 2949-2963; doi:10.3390/md11082949
Received: 13 June 2013 / Revised: 20 July 2013 / Accepted: 30 July 2013 / Published: 15 August 2013
Cited by 10 | PDF Full-text (495 KB) | HTML Full-text | XML Full-text
Abstract
The cosmopolitan and increasing distribution of Cylindrospermopsis raciborskii can be attributed to its ecophysiological plasticity and tolerance to changing environmental factors in water bodies. In reservoirs in the semi-arid region of Brazil, the presence and common dominance of C. raciborskii have been described
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The cosmopolitan and increasing distribution of Cylindrospermopsis raciborskii can be attributed to its ecophysiological plasticity and tolerance to changing environmental factors in water bodies. In reservoirs in the semi-arid region of Brazil, the presence and common dominance of C. raciborskii have been described in waters that are considered hard. We investigated the response of a Brazilian C. raciborskii strain to water hardness by evaluating its growth and saxitoxin production. Based on environmental data, a concentration of 5 mM of different carbonate salts was tested. These conditions affected growth either positively (MgCO3) or negatively (CaCO3 and Na2CO3). As a control for the addition of cations, MgCl2, CaCl2 and NaCl were tested at 5 or 10 mM, and MgCl2 stimulated growth, NaCl slowed but sustained growth, and CaCl2 inhibited growth. Most of the tested treatments increased the saxitoxin (STX) cell quota after six days of exposure. After 12 days, STX production returned to concentrations similar to that of the control, indicating an adaptation to the altered water conditions. In the short term, cell exposure to most of the tested conditions favored STX production over neoSTX production. These results support the noted plasticity of C. raciborskii and highlight its potential to thrive in hard waters. Additionally, the observed relationship between saxitoxin production and water ion concentrations characteristic of the natural environments can be important for understanding toxin content variation in other harmful algae that produce STX. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Magnetic Resonance Imaging for Rapid Screening for the Nephrotoxic and Hepatotoxic Effects of Microcystins
Mar. Drugs 2013, 11(8), 2785-2798; doi:10.3390/md11082785
Received: 30 April 2013 / Revised: 4 June 2013 / Accepted: 19 July 2013 / Published: 5 August 2013
Cited by 1 | PDF Full-text (1071 KB) | HTML Full-text | XML Full-text
Abstract
In vivo visualization of kidney and liver damage by Magnetic Resonance Imaging (MRI) may offer an advantage when there is a need for a simple, non-invasive and rapid method for screening of the effects of potential nephrotoxic and hepatotoxic substances in chronic experiments.
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In vivo visualization of kidney and liver damage by Magnetic Resonance Imaging (MRI) may offer an advantage when there is a need for a simple, non-invasive and rapid method for screening of the effects of potential nephrotoxic and hepatotoxic substances in chronic experiments. Here, we used MRI for monitoring chronic intoxication with microcystins (MCs) in rat. Male adult Wistar rats were treated every other day for eight months, either with MC-LR (10 μg/kg i.p.) or MC-YR (10 μg/kg i.p.). Control groups were treated with vehicle solutions. T1-weighted MR-images were acquired before and at the end of the eight months experimental period. Kidney injury induced by the MCs presented with the increased intensity of T1-weighted MR-signal of the kidneys and liver as compared to these organs from the control animals treated for eight months, either with the vehicle solution or with saline. The intensification of the T1-weighted MR-signal correlated with the increased volume density of heavily injured tubuli (R2 = 0.77), with heavily damaged glomeruli (R2 = 0.84) and with volume density of connective tissue (R2 = 0.72). The changes in the MR signal intensity probably reflect the presence of an abundant proteinaceous material within the dilated nephrons and proliferation of the connective tissue. T1-weighted MRI-is a valuable method for the in vivo screening of kidney and liver damage in rat models of intoxication with hepatotoxic and nephrotoxic agents, such as microcystins. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessArticle Occurrence of the Microcystins MC-LW and MC-LF in Dutch Surface Waters and Their Contribution to Total Microcystin Toxicity
Mar. Drugs 2013, 11(7), 2643-2654; doi:10.3390/md11072643
Received: 29 May 2013 / Revised: 8 July 2013 / Accepted: 12 July 2013 / Published: 22 July 2013
Cited by 14 | PDF Full-text (523 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Microcystins (MCs) are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is
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Microcystins (MCs) are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is most abundant and mostly used for risk assessments. As little is known about the presence of these two variants in The Netherlands, we determined their occurrence by analyzing 88 water samples and 10 scum samples for eight MC variants ((dm-7-)MC-RR, MC-YR, (dm-7-)MC-LR, MC-LY, MC-LW and MC-LF) by liquid chromatography with tandem mass spectrometry detection. All analyzed MC variants were detected, and MC-LW and/or MC-LF were present in 32% of the MC containing water samples. When MC-LW and MC-LF were present, they contributed to nearly 10% of the total MC concentrations, but due to their suspected high toxicity, their average contribution to the total MC toxicity was estimated to be at least 45%. Given the frequent occurrence and possible high toxicity of MC-LW and MC-LF, it seems better to base health risk assessments on the toxicity contributions of different MC variants than on MC-LR concentrations alone. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Assessment of Chemical and Physico-Chemical Properties of Cyanobacterial Lipids for Biodiesel Production
Mar. Drugs 2013, 11(7), 2365-2381; doi:10.3390/md11072365
Received: 26 April 2013 / Revised: 8 June 2013 / Accepted: 18 June 2013 / Published: 4 July 2013
Cited by 11 | PDF Full-text (871 KB) | HTML Full-text | XML Full-text
Abstract
Five non-toxin producing cyanobacterial isolates from the genera Synechococcus, Trichormus, Microcystis, Leptolyngbya and Chlorogloea were examined in terms of quantity and quality as lipid feedstock for biofuel production. Under the conditions used in this study, the biomass productivity ranged from
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Five non-toxin producing cyanobacterial isolates from the genera Synechococcus, Trichormus, Microcystis, Leptolyngbya and Chlorogloea were examined in terms of quantity and quality as lipid feedstock for biofuel production. Under the conditions used in this study, the biomass productivity ranged from 3.7 to 52.7 mg·L−1·day−1 in relation to dry biomass, while the lipid productivity varied between 0.8 and 14.2 mg·L−1·day−1. All cyanobacterial strains evaluated yielded lipids with similar fatty acid composition to those present in the seed oils successfully used for biodiesel synthesis. However, by combining biomass and lipid productivity parameters, the greatest potential was found for Synechococcus sp. PCC7942, M. aeruginosa NPCD-1 and Trichormus sp. CENA77. The chosen lipid samples were further characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosity and thermogravimetry and used as lipid feedstock for biodiesel synthesis by heterogeneous catalysis. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessArticle Chemoecological Screening Reveals High Bioactivity in Diverse Culturable Portuguese Marine Cyanobacteria
Mar. Drugs 2013, 11(4), 1316-1335; doi:10.3390/md11041316
Received: 7 January 2013 / Revised: 12 March 2013 / Accepted: 27 March 2013 / Published: 22 April 2013
Cited by 7 | PDF Full-text (1491 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Marine cyanobacteria, notably those from tropical regions, are a rich source of bioactive secondary metabolites. Tropical marine cyanobacteria often grow to high densities in the environment, allowing direct isolation of many secondary metabolites from field-collected material. However, in temperate environments culturing is usually
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Marine cyanobacteria, notably those from tropical regions, are a rich source of bioactive secondary metabolites. Tropical marine cyanobacteria often grow to high densities in the environment, allowing direct isolation of many secondary metabolites from field-collected material. However, in temperate environments culturing is usually required to produce enough biomass for investigations of their chemical constituents. In this work, we cultured a selection of novel and diverse cyanobacteria isolated from the Portuguese coast, and tested their organic extracts in a series of ecologically-relevant bioassays. The majority of the extracts showed activity in at least one of the bioassays, all of which were run in very small scale. Phylogenetically related isolates exhibited different activity profiles, highlighting the value of microdiversity for bioprospection studies. Furthermore, LC-MS analyses of selected active extracts suggested the presence of previously unidentified secondary metabolites. Overall, the screening strategy employed here, in which previously untapped cyanobacterial diversity was combined with multiple bioassays, proved to be a successful strategy and allowed the selection of several strains for further investigations based on their bioactivity profiles. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Review

Jump to: Research

Open AccessReview Cyanobacterial Metabolite Calothrixins: Recent Advances in Synthesis and Biological Evaluation
Mar. Drugs 2016, 14(1), 17; doi:10.3390/md14010017
Received: 5 August 2015 / Revised: 22 December 2015 / Accepted: 4 January 2016 / Published: 12 January 2016
Cited by 2 | PDF Full-text (16806 KB) | HTML Full-text | XML Full-text
Abstract
The marine environment is host to unparalleled biological and chemical diversity, making it an attractive resource for the discovery of new therapeutics for a plethora of diseases. Compounds that are extracted from cyanobacteria are of special interest due to their unique structural scaffolds
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The marine environment is host to unparalleled biological and chemical diversity, making it an attractive resource for the discovery of new therapeutics for a plethora of diseases. Compounds that are extracted from cyanobacteria are of special interest due to their unique structural scaffolds and capacity to produce potent pharmaceutical and biotechnological traits. Calothrixins A and B are two cyanobacterial metabolites with a structural assembly of quinoline, quinone, and indole pharmacophores. This review surveys recent advances in the synthesis and evaluation of the biological activities of calothrixins. Due to the low isolation yields from the marine source and the promise this scaffold holds for anticancer and antimicrobial drugs, organic and medicinal chemists around the world have embarked on developing efficient synthetic routes to produce calothrixins. Since the first review appeared in 2009, 11 novel syntheses of calothrixins have been published in the efforts to develop methods that contain fewer steps and higher-yielding reactions. Calothrixins have shown their potential as topoisomerase I poisons for their cytotoxicity in cancer. They have also been observed to target various aspects of RNA synthesis in bacteria. Further investigation into the exact mechanism for their bioactivity is still required for many of its analogs. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessReview Cyanobactins from Cyanobacteria: Current Genetic and Chemical State of Knowledge
Mar. Drugs 2015, 13(11), 6910-6946; doi:10.3390/md13116910
Received: 25 June 2015 / Revised: 22 September 2015 / Accepted: 30 October 2015 / Published: 13 November 2015
Cited by 5 | PDF Full-text (4089 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacteria are considered to be one of the most promising sources of new, natural products. Apart from non-ribosomal peptides and polyketides, ribosomally synthesized and post-translationally modified peptides (RiPPs) are one of the leading groups of bioactive compounds produced by cyanobacteria. Among these, cyanobactins
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Cyanobacteria are considered to be one of the most promising sources of new, natural products. Apart from non-ribosomal peptides and polyketides, ribosomally synthesized and post-translationally modified peptides (RiPPs) are one of the leading groups of bioactive compounds produced by cyanobacteria. Among these, cyanobactins have sparked attention due to their interesting bioactivities and for their potential to be prospective candidates in the development of drugs. It is assumed that the primary source of cyanobactins is cyanobacteria, although these compounds have also been isolated from marine animals such as ascidians, sponges and mollusks. The aim of this review is to update the current knowledge of cyanobactins, recognized as being produced by cyanobacteria, and to emphasize their genetic clusters and chemical structures as well as their bioactivities, ecological roles and biotechnological potential. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
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Open AccessReview Phylogeny and Biogeography of Cyanobacteria and Their Produced Toxins
Mar. Drugs 2013, 11(11), 4350-4369; doi:10.3390/md11114350
Received: 16 July 2013 / Revised: 29 August 2013 / Accepted: 9 October 2013 / Published: 1 November 2013
Cited by 10 | PDF Full-text (404 KB) | HTML Full-text | XML Full-text
Abstract
Phylogeny is an evolutionary reconstruction of the past relationships of DNA or protein sequences and it can further be used as a tool to assess population structuring, genetic diversity and biogeographic patterns. In the microbial world, the concept that everything is everywhere is
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Phylogeny is an evolutionary reconstruction of the past relationships of DNA or protein sequences and it can further be used as a tool to assess population structuring, genetic diversity and biogeographic patterns. In the microbial world, the concept that everything is everywhere is widely accepted. However, it is much debated whether microbes are easily dispersed globally or whether they, like many macro-organisms, have historical biogeographies. Biogeography can be defined as the science that documents the spatial and temporal distribution of a given taxa in the environment at local, regional and continental scales. Speciation, extinction and dispersal are proposed to explain the generation of biogeographic patterns. Cyanobacteria are a diverse group of microorganisms that inhabit a wide range of ecological niches and are well known for their toxic secondary metabolite production. Knowledge of the evolution and dispersal of these microorganisms is still limited, and further research to understand such topics is imperative. Here, we provide a compilation of the most relevant information regarding these issues to better understand the present state of the art as a platform for future studies, and we highlight examples of both phylogenetic and biogeographic studies in non-symbiotic cyanobacteria and cyanotoxins. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessReview Development of Synechocystis sp. PCC 6803 as a Phototrophic Cell Factory
Mar. Drugs 2013, 11(8), 2894-2916; doi:10.3390/md11082894
Received: 14 June 2013 / Revised: 14 June 2013 / Accepted: 15 July 2013 / Published: 13 August 2013
Cited by 26 | PDF Full-text (443 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacteria (blue-green algae) play profound roles in ecology and biogeochemistry. One model cyanobacterial species is the unicellular cyanobacterium Synechocystis sp. PCC 6803. This species is highly amenable to genetic modification. Its genome has been sequenced and many systems biology and molecular biology tools are available
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Cyanobacteria (blue-green algae) play profound roles in ecology and biogeochemistry. One model cyanobacterial species is the unicellular cyanobacterium Synechocystis sp. PCC 6803. This species is highly amenable to genetic modification. Its genome has been sequenced and many systems biology and molecular biology tools are available to study this bacterium. Recently, researchers have put significant efforts into understanding and engineering this bacterium to produce chemicals and biofuels from sunlight and CO2. To demonstrate our perspective on the application of this cyanobacterium as a photosynthesis-based chassis, we summarize the recent research on Synechocystis 6803 by focusing on five topics: rate-limiting factors for cell cultivation; molecular tools for genetic modifications; high-throughput system biology for genome wide analysis; metabolic modeling for physiological prediction and rational metabolic engineering; and applications in producing diverse chemicals. We also discuss the particular challenges for systems analysis and engineering applications of this microorganism, including precise characterization of versatile cell metabolism, improvement of product rates and titers, bioprocess scale-up, and product recovery. Although much progress has been achieved in the development of Synechocystis 6803 as a phototrophic cell factory, the biotechnology for “Compounds from Synechocystis” is still significantly lagging behind those for heterotrophic microbes (e.g., Escherichia coli). Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)
Open AccessReview Interpreting the Possible Ecological Role(s) of Cyanotoxins: Compounds for Competitive Advantage and/or Physiological Aide?
Mar. Drugs 2013, 11(7), 2239-2258; doi:10.3390/md11072239
Received: 10 April 2013 / Revised: 14 May 2013 / Accepted: 29 May 2013 / Published: 27 June 2013
Cited by 17 | PDF Full-text (564 KB) | HTML Full-text | XML Full-text
Abstract
To date, most research on freshwater cyanotoxin(s) has focused on understanding the dynamics of toxin production and decomposition, as well as evaluating the environmental conditions that trigger toxin production, all with the objective of informing management strategies and options for risk reduction. Comparatively
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To date, most research on freshwater cyanotoxin(s) has focused on understanding the dynamics of toxin production and decomposition, as well as evaluating the environmental conditions that trigger toxin production, all with the objective of informing management strategies and options for risk reduction. Comparatively few research studies have considered how this information can be used to understand the broader ecological role of cyanotoxin(s), and the possible applications of this knowledge to the management of toxic blooms. This paper explores the ecological, toxicological, and genetic evidence for cyanotoxin production in natural environments. The possible evolutionary advantages of toxin production are grouped into two main themes: That of “competitive advantage” or “physiological aide”. The first grouping illustrates how compounds produced by cyanobacteria may have originated from the need for a cellular defence mechanism, in response to grazing pressure and/or resource competition. The second grouping considers the contribution that secondary metabolites make to improved cellular physiology, through benefits to homeostasis, photosynthetic efficiencies, and accelerated growth rates. The discussion also includes other factors in the debate about possible evolutionary roles for toxins, such as different modes of exposures and effects on non-target (i.e., non-competitive) species. The paper demonstrates that complex and multiple factors are at play in driving evolutionary processes in aquatic environments. This information may provide a fresh perspective on managing toxic blooms, including the need to use a “systems approach” to understand how physico-chemical conditions, as well biological stressors, interact to trigger toxin production. Full article
(This article belongs to the Special Issue Compounds from Cyanobacteria)

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