Natural Products from Microalgae and Cyanobacteria

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Microbial Biotechnology".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 14740

Special Issue Editors


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Guest Editor
Department of Biosciences, College of Science, Swansea University, Swansea, UK
Interests: microalgae; cyanobacteria; marine microbial ecology; algal natural products; ‘omics’
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Guest Editor
Scottish Association for Marine Science (SAMS), Scottish Marine Institute, Oban PA37 1QA, UK
Interests: marine biotechnology; phycology; macroalgae; seaweed; microalgae

Special Issue Information

Dear Colleagues,

Microalgae and cyanobacteria are highly diverse ubiquitous groups of aquatic microorganisms. They play an essential ecological role in maintaining carbon and other nutrient balance in aquatic systems and form the base of all aquatic food chains. Surprisingly though, microalgae and cyanobacteria have lagged behind bacteria and fungi both in terms of availability of genome sequences and in their use as natural products. However, the decreasing costs in genome sequencing and increasing availability of ‘omics’ technologies has led to the increasing availability of algal and cyanobacterial genomes. This presents new opportunities in natural product discovery from microalgae and cyanobacteria. In this Special Issue, we welcome papers linking the use of ‘omics’ technologies with natural product discovery. Papers addressing better understanding and discovery of new metabolic pathways and gene clusters are particularly welcome. Discoveries and future potential of existing and new groups are encouraged covering but not limited to fatty acids, carotenoids, terpenoids, peptides, polyketides. 

Prof. Carole Llewellyn
Prof. Dr. Michele S. Stanley
Guest Editors

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Keywords

  • microalgae
  • cyanobacteria
  • natural products
  • omics
  • metabolic pathways
  • secondary metabolites
  • metabolic engineering

Published Papers (4 papers)

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Research

24 pages, 16063 KiB  
Article
Glucosidase Inhibitors Screening in Microalgae and Cyanobacteria Isolated from the Amazon and Proteomic Analysis of Inhibitor Producing Synechococcus sp. GFB01
by Diana Gomes Gradíssimo, Vivian Cássia Oliveira da Silva, Luciana Pereira Xavier, Sidney Vasconcelos do Nascimento, Rafael Borges da Silva Valadares, Silvia Maria Mathes Faustino, Maria Paula Cruz Schneider and Agenor Valadares Santos
Microorganisms 2021, 9(8), 1593; https://doi.org/10.3390/microorganisms9081593 - 27 Jul 2021
Cited by 7 | Viewed by 2692
Abstract
Microalgae and cyanobacteria are good sources for prospecting metabolites of biotechnological interest, including glucosidase inhibitors. These inhibitors act on enzymes related to various biochemical processes; they are involved in metabolic diseases, such as diabetes and Gaucher disease, tumors and viral infections, thus, they [...] Read more.
Microalgae and cyanobacteria are good sources for prospecting metabolites of biotechnological interest, including glucosidase inhibitors. These inhibitors act on enzymes related to various biochemical processes; they are involved in metabolic diseases, such as diabetes and Gaucher disease, tumors and viral infections, thus, they are interesting hubs for the development of new drugs and therapies. In this work, the screening of 63 environmental samples collected in the Brazilian Amazon found activity against β-glucosidase, of at least 60 min, in 13.85% of the tested extracts, with Synechococcus sp. GFB01 showing inhibitory activity of 90.2% for α-glucosidase and 96.9% against β-glucosidase. It was found that the nutritional limitation due to a reduction in the concentration of sodium nitrate, despite not being sufficient to cause changes in cell growth and photosynthetic apparatus, resulted in reduced production of α and β-glucosidase inhibitors and differential protein expression. The proteomic analysis of cyanobacteria isolated from the Amazon is unprecedented, with this being the first work to evaluate the protein expression of Synechococcus sp. GFB01 subjected to nutritional stress. This evaluation helps to better understand the metabolic responses of this organism, especially related to the production of inhibitors, adding knowledge to the industrial potential of these cyanobacterial compounds. Full article
(This article belongs to the Special Issue Natural Products from Microalgae and Cyanobacteria)
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14 pages, 3383 KiB  
Article
Assessment of Phycocyanin Extraction from Cyanidium caldarium by Spark Discharges, Compared to Freeze-Thaw Cycles, Sonication, and Pulsed Electric Fields
by Marie-Christine Sommer, Martina Balazinski, Raphael Rataj, Sebastian Wenske, Juergen F. Kolb and Katja Zocher
Microorganisms 2021, 9(7), 1452; https://doi.org/10.3390/microorganisms9071452 - 6 Jul 2021
Cited by 19 | Viewed by 3047
Abstract
Phycocyanin is a blue colored pigment, synthesized by several species of cyanobacteria and red algae. Besides the application as a food-colorant, the pigmented protein is of high interest as a pharmaceutically and nutritionally valuable compound. Since cyanobacteria-derived phycocyanin is thermolabile, red algae that [...] Read more.
Phycocyanin is a blue colored pigment, synthesized by several species of cyanobacteria and red algae. Besides the application as a food-colorant, the pigmented protein is of high interest as a pharmaceutically and nutritionally valuable compound. Since cyanobacteria-derived phycocyanin is thermolabile, red algae that are adapted to high temperatures are an interesting source for phycocyanin extraction. Still, the extraction of high quality phycocyanin from red algae is challenging due to the strong and rigid cell wall. Since standard techniques show low yields, alternative methods are needed. Recently, spark discharges have been shown to gently disintegrate microalgae and thereby enable the efficient extraction of susceptible proteins. In this study, the applicability of spark discharges for phycocyanin extraction from the red alga Cyanidium caldarium was investigated. The efficiency of 30 min spark discharges was compared with standard treatment protocols, such as three times repeated freeze-thaw cycles, sonication, and pulsed electric fields. Input energy for all physical methods were kept constant at 11,880 J to ensure comparability. The obtained extracts were evaluated by photometric and fluorescent spectroscopy. Highest extraction yields were achieved with sonication (53 mg/g dry weight (dw)) and disintegration by spark discharges (4 mg/g dw) while neither freeze-thawing nor pulsed electric field disintegration proved effective. The protein analysis via LC-MS of the former two extracts revealed a comparable composition of phycobiliproteins. Despite the lower total concentration of phycocyanin after application of spark discharges, the purity in the raw extract was higher in comparison to the extract attained by sonication. Full article
(This article belongs to the Special Issue Natural Products from Microalgae and Cyanobacteria)
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12 pages, 1620 KiB  
Article
Response of Key Metabolites during a UV-A Exposure Time-Series in the Cyanobacterium Chlorogloeopsis fritschii PCC 6912
by Bethan Kultschar, Ed Dudley, Steve Wilson and Carole Anne Llewellyn
Microorganisms 2021, 9(5), 910; https://doi.org/10.3390/microorganisms9050910 - 24 Apr 2021
Cited by 1 | Viewed by 2099
Abstract
Ultraviolet A (UV-A) is the major component of UV radiation reaching the Earth’s surface, causing indirect damage to photosynthetic organisms via the production of reactive oxygen species (ROS). In comparison, UV-B causes both direct damage to biomolecules and indirect damage. UV-B is well [...] Read more.
Ultraviolet A (UV-A) is the major component of UV radiation reaching the Earth’s surface, causing indirect damage to photosynthetic organisms via the production of reactive oxygen species (ROS). In comparison, UV-B causes both direct damage to biomolecules and indirect damage. UV-B is well studied in cyanobacterial research due to their long evolutionary history and adaptation to high levels of UV, with less work on the effects of UV-A. In this study, the response of key metabolites in Chlorogloeopsis fritschii (C. fritschii) during 48 h of photosynthetically active radiation (PAR, 15 µmol·m−2·s−1) supplemented with UV-A (11 µmol·m−2·s−1) was investigated using gas chromatography- mass spectrometry (GC-MS). Results showed an overall significant increase in metabolite levels up to 24 h of UV-A exposure. Compared with previously reported UV-B (PAR + UV-B) and PAR only results, UV-A showed more similarity compared to PAR only exposure as opposed to supplemented UV-B. The amino acids glutamate, phenylalanine and leucine showed differences in levels between UV (both supplemented UV-A and supplemented UV-B) and PAR only (non-supplemented PAR), hinting to their relevance in UV stress response. The fatty acids, palmitic and stearic acid, showed positive log2 fold-change (FC) in supplemented UV-A and PAR only experiments but negative log2 FC in UV-B, indicating the more harmful effect of UV-B on primary metabolism. Less research has been conducted on UV-A exposure and cyanobacteria, a potential environmental stimuli for the optimisation of metabolites for industrial biotechnology. This study will add to the literature and knowledge on UV-A stress response at the metabolite level in cyanobacteria, especially within the less well-known species C. fritschii. Full article
(This article belongs to the Special Issue Natural Products from Microalgae and Cyanobacteria)
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16 pages, 3310 KiB  
Article
Exploring the Chemical Space of Macro- and Micro-Algae Using Comparative Metabolomics
by Alison H. Hughes, Florent Magot, Ahmed F. Tawfike, Cecilia Rad-Menéndez, Naomi Thomas, Louise C. Young, Laura Stucchi, Daniele Carettoni, Michele S. Stanley, RuAngelie Edrada-Ebel and Katherine R. Duncan
Microorganisms 2021, 9(2), 311; https://doi.org/10.3390/microorganisms9020311 - 3 Feb 2021
Cited by 15 | Viewed by 5911
Abstract
With more than 156,000 described species, eukaryotic algae (both macro- and micro-algae) are a rich source of biological diversity, however their chemical diversity remains largely unexplored. Specialised metabolites with promising biological activities have been widely reported for seaweeds, and more recently extracts from [...] Read more.
With more than 156,000 described species, eukaryotic algae (both macro- and micro-algae) are a rich source of biological diversity, however their chemical diversity remains largely unexplored. Specialised metabolites with promising biological activities have been widely reported for seaweeds, and more recently extracts from microalgae have exhibited activity in anticancer, antimicrobial, and antioxidant screens. However, we are still missing critical information on the distinction of chemical profiles between macro- and microalgae, as well as the chemical space these metabolites cover. This study has used an untargeted comparative metabolomics approach to explore the chemical diversity of seven seaweeds and 36 microalgal strains. A total of 1390 liquid chromatography-mass spectrometry (LC-MS) features were detected, representing small organic algal metabolites, with no overlap between the seaweeds and microalgae. An in-depth analysis of four Dunaliella tertiolecta strains shows that environmental factors may play a larger role than phylogeny when classifying their metabolomic profiles. Full article
(This article belongs to the Special Issue Natural Products from Microalgae and Cyanobacteria)
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