Metabolites of Diatoms – from Chemical Ecology to Their Potential Application in Biotechnology

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

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 15221

Special Issue Editor

Special Issue Information

Dear Colleagues,

Diatoms are among the most cosmopolitan and diverse photosynthetic algal groups and appear at the bottom of most pelagic and benthic food webs in aquatic ecosystems. The productivity of diatoms is controlled by a number of environmental factors, many of which are currently undergoing substantial changes due to anthropogenic influences (e.g., climate change, eutrophication, and pollution). There is growing recognition of the central role that chemical ecology plays in maintaining the structure, function and balance of marine ecosystems. Many key life processes including food source identification and selectivity; prey location and capture; mate recognition and location; chemical defence; behaviour; and population synchronisation are mediated by chemical interactions. A scenario in which such chemical stimuli are removed or altered by manmade chemicals could result in a catastrophic cascade of disruption to inter- and intra-specific interactions at individual, population and community levels. Despite significant progress in the investigation of specific metabolic pathways in diatoms, still little is known, for example, about alterations in bioactive molecule production during diatoms exposure to environmental stress conditions. This Special Issue will cover all aspects of chemical ecology of marine diatoms, including their physiology, biosynthesis, diversity of metabolites, and ecological role in potential applications in biotechnology and pharmaceutical industry.

Dr. Valerio Zupo
Guest Editor

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Keywords

  • diatoms
  • chemical ecology
  • stress physiology
  • “omics” approaches
  • bioactive molecules
  • aquaculture
  • biotechnology

Published Papers (4 papers)

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Research

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17 pages, 4558 KiB  
Article
Two Benthic Diatoms, Nanofrustulum shiloi and Striatella unipunctata, Encapsulated in Alginate Beads, Influence the Reproductive Efficiency of Paracentrotus lividus by Modulating the Gene Expression
by Francesca Glaviano, Nadia Ruocco, Emanuele Somma, Giuseppe De Rosa, Virginia Campani, Pasquale Ametrano, Davide Caramiello, Maria Costantini and Valerio Zupo
Mar. Drugs 2021, 19(4), 230; https://0-doi-org.brum.beds.ac.uk/10.3390/md19040230 - 17 Apr 2021
Cited by 1 | Viewed by 2190
Abstract
Physiological effects of algal metabolites is a key step for the isolation of interesting bioactive compounds. Invertebrate grazers may be fed on live diatoms or dried, pelletized, and added to compound feeds. Any method may reveal some shortcomings, due to the leaking of [...] Read more.
Physiological effects of algal metabolites is a key step for the isolation of interesting bioactive compounds. Invertebrate grazers may be fed on live diatoms or dried, pelletized, and added to compound feeds. Any method may reveal some shortcomings, due to the leaking of wound-activated compounds in the water prior to ingestion. For this reason, encapsulation may represent an important step of bioassay-guided fractionation, because it may assure timely preservation of the active compounds. Here we test the effects of the inclusion in alginate (biocompatible and non-toxic delivery system) matrices to produce beads containing two benthic diatoms for sea urchin Paracentrotus lividus feeding. In particular, we compared the effects of a diatom whose influence on P. lividus was known (Nanofrustulum shiloi) and those of a diatom suspected to be harmful to marine invertebrates, because it is often present in blooms (Striatella unipunctata). Dried N. shiloi and S. unipunctata were offered for one month after encapsulation in alginate hydrogel beads and the larvae produced by sea urchins were checked for viability and malformations. The results indicated that N. shiloi, already known for its toxigenic effects on sea urchin larvae, fully conserved its activity after inclusion in alginate beads. On the whole, benthic diatoms affected the embryogenesis of P. lividus, altering the expression of several genes involved in stress response, development, skeletogenesis and detoxification processes. Interactomic analysis suggested that both diatoms activated a similar stress response pathway, through the up-regulation of hsp60, hsp70, NF-κB, 14-3-3 ε and MDR1 genes. This research also demonstrates that the inclusion in alginate beads may represent a feasible technique to isolate diatom-derived bioactive compounds. Full article
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17 pages, 3333 KiB  
Article
Adding Zooplankton to the OSMAC Toolkit: Effect of Grazing Stress on the Metabolic Profile and Bioactivity of a Diatom
by Renate Døving Osvik, Richard Andre Ingebrigtsen, Maria Fredrika Norrbin, Jeanette Hammer Andersen, Hans Christian Eilertsen and Espen Holst Hansen
Mar. Drugs 2021, 19(2), 87; https://0-doi-org.brum.beds.ac.uk/10.3390/md19020087 - 03 Feb 2021
Cited by 6 | Viewed by 2713
Abstract
“One strain many compounds” (OSMAC) based approaches have been widely used in the search for bioactive compounds. Introducing stress factors like nutrient limitation, UV-light or cocultivation with competing organisms has successfully been used in prokaryote cultivation. It is known that diatom physiology is [...] Read more.
“One strain many compounds” (OSMAC) based approaches have been widely used in the search for bioactive compounds. Introducing stress factors like nutrient limitation, UV-light or cocultivation with competing organisms has successfully been used in prokaryote cultivation. It is known that diatom physiology is affected by changed cultivation conditions such as temperature, nutrient concentration and light conditions. Cocultivation, though, is less explored. Hence, we wanted to investigate whether grazing pressure can affect the metabolome of the marine diatom Porosira glacialis, and if the stress reaction could be detected as changes in bioactivity. P. glacialis cultures were mass cultivated in large volume bioreactor (6000 L), first as a monoculture and then as a coculture with live zooplankton. Extracts of the diatom biomass were screened in a selection of bioactivity assays: inhibition of biofilm formation, antibacterial and cell viability assay on human cells. Bioactivity was found in all bioassays performed. The viability assay towards normal lung fibroblasts revealed that P. glacialis had higher bioactivity when cocultivated with zooplankton than in monoculture. Cocultivation with diatoms had no noticeable effect on the activity against biofilm formation or bacterial growth. The metabolic profiles were analyzed showing the differences in diatom metabolomes between the two culture conditions. The experiment demonstrates that grazing stress affects the biochemistry of P. glacialis and thus represents a potential tool in the OSMAC toolkit. Full article
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Review

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20 pages, 5412 KiB  
Review
Anticancer Compounds Derived from Marine Diatoms
by Hanaa Ali Hussein and Mohd Azmuddin Abdullah
Mar. Drugs 2020, 18(7), 356; https://0-doi-org.brum.beds.ac.uk/10.3390/md18070356 - 09 Jul 2020
Cited by 40 | Viewed by 5549
Abstract
Cancer is the main cause of death worldwide, so the discovery of new and effective therapeutic agents must be urgently addressed. Diatoms are rich in minerals and secondary metabolites such as saturated and unsaturated fatty acids, esters, acyl lipids, sterols, proteins, and flavonoids. [...] Read more.
Cancer is the main cause of death worldwide, so the discovery of new and effective therapeutic agents must be urgently addressed. Diatoms are rich in minerals and secondary metabolites such as saturated and unsaturated fatty acids, esters, acyl lipids, sterols, proteins, and flavonoids. These bioactive compounds have been reported as potent anti-cancer, anti-oxidant and anti-bacterial agents. Diatoms are unicellular photosynthetic organisms, which are important in the biogeochemical circulation of silica, nitrogen, and carbon, attributable to their short growth-cycle and high yield. The biosilica of diatoms is potentially effective as a carrier for targeted drug delivery in cancer therapy due to its high surface area, nano-porosity, bio-compatibility, and bio-degradability. In vivo studies have shown no significant symptoms of tissue damage in animal models, suggesting the suitability of a diatoms-based system as a safe nanocarrier in nano-medicine applications. This review presents an overview of diatoms’ microalgae possessing anti-cancer activities and the potential role of the diatoms and biosilica in the delivery of anticancer drugs. Diatoms-based antibodies and vitamin B12 as drug carriers are also elaborated. Full article
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25 pages, 1462 KiB  
Review
Multiple Roles of Diatom-Derived Oxylipins within Marine Environments and Their Potential Biotechnological Applications
by Nadia Ruocco, Luisa Albarano, Roberta Esposito, Valerio Zupo, Maria Costantini and Adrianna Ianora
Mar. Drugs 2020, 18(7), 342; https://0-doi-org.brum.beds.ac.uk/10.3390/md18070342 - 30 Jun 2020
Cited by 22 | Viewed by 3922
Abstract
The chemical ecology of marine diatoms has been the subject of several studies in the last decades, due to the discovery of oxylipins with multiple simultaneous functions including roles in chemical defence (antipredator, allelopathic and antibacterial compounds) and/or cell-to-cell signalling. Diatoms represent a [...] Read more.
The chemical ecology of marine diatoms has been the subject of several studies in the last decades, due to the discovery of oxylipins with multiple simultaneous functions including roles in chemical defence (antipredator, allelopathic and antibacterial compounds) and/or cell-to-cell signalling. Diatoms represent a fundamental compartment of marine ecosystems because they contribute to about 45% of global primary production even if they represent only 1% of the Earth’s photosynthetic biomass. The discovery that they produce several toxic metabolites deriving from the oxidation of polyunsaturated fatty acids, known as oxylipins, has changed our perspectives about secondary metabolites shaping plant–plant and plant–animal interactions in the oceans. More recently, their possible biotechnological potential has been evaluated, with promising results on their potential as anticancer compounds. Here, we focus on some recent findings in this field obtained in the last decade, investigating the role of diatom oxylipins in cell-to-cell communication and their negative impact on marine biota. Moreover, we also explore and discuss the possible biotechnological applications of diatom oxylipins. Full article
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