Special Issue "Marine Antibiotics 2020"

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

Deadline for manuscript submissions: closed (5 February 2021) | Viewed by 15386

Special Issue Editor

Dr. Yannick Fleury
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Guest Editor
LBCM, Laboratoire de Biotechnologie et Chimie Marines Université de Brest, Quimper, France
Interests: antibiotics from marine microbiota; antibiofilm; gram negative pathogens; antimicrobial peptides
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Special Issue Information

Dear Colleagues,

At the outset of the antibiotic era, as early as 1945, A. Fleming warned against the bacterial resistance induced by antibiotic under-dosing during his Nobel Prize lecture on penicillin discovery. He announced nothing less than the post-antibiotic era. Since 1945, the abusive and/or incorrect antibiotic uses combined with the lack of renewal of antibiotic compounds in the clinical armamentarium have constituted a ticking time bomb. Indeed, antibiotic misuse has resulted in the selection of bacteria exhibiting multidrug resistance (MDR), extensive drug resistance (XDR), and pandrug resistance (PDR). Nowadays, antimicrobial resistance (AMR) has become a global public health threat. It is expected to be one of the leading causes of death in the world in 2050. Faced with these dire predictions, a plethora of actions, networks, and calls for projects have been implemented nationally and internationally. Obviously, learning from errors, the prevention of antibiotic misuses, resistance detection and diagnosis, and achieving public awareness are leverage actions with which to fight antimicrobial resistance. However, it is clear that the renewal of the therapeutic arsenal is a major priority, if only to treat patients.

Marine organisms are still under-explored at the biochemical level. The hologenome theory of evolution and the advent of new generation DNA sequencing have highlighted the intimate relationships between microbiota and host in cnidarian and sponges. Although the way a host controls or is controlled by its microbiota remains to be clarified, marine holobionts still represent a mine of innovative compounds and a source of inspiration with which to design potent and effective drugs to combat AMR.

The first Special Issue dedicated to marine antibiotics was managed by Prof. Sergey Zotchev in 2012. It assembled 11 papers, which have collected, to date, 247 citations (according to the Web of Science). More than an update, I would like this Special Issue to aggregate innovative data regarding marine antibiotics, whatever their origin (archeabacteria, eubacteria, algae, animals, or even metagenomic data mining), biosynthesis, chemical nature (PKS, NRPS, peptides, alkaloids, etc.), or mechanisms of actions. Original research as well as review articles are welcome. Scientists are invited to contribute in order to combine expertise in (meta)data mining, microbiology, biochemistry, biotechnology, cellular biology, and medicine.

Dr. Yannick Fleury
Guest Editor

Manuscript Submission Information

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. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind 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 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Published Papers (6 papers)

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Editorial

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Editorial
Marine Antibiotics 2020
Mar. Drugs 2021, 19(6), 351; https://doi.org/10.3390/md19060351 - 21 Jun 2021
Viewed by 1092
Abstract
The range of environmental conditions in marine life is tremendous at different physico-chemical criteria (temperature, light, pressure and salinity) [...] Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)

Research

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Article
Alterins Produced by Oyster-Associated Pseudoalteromonas Are Antibacterial Cyclolipopeptides with LPS-Binding Activity
Mar. Drugs 2020, 18(12), 630; https://doi.org/10.3390/md18120630 - 10 Dec 2020
Cited by 8 | Viewed by 1823
Abstract
Discovery after discovery, host-associated microbiota reveal a growing list of positive effects on host homeostasis by contributing to host nutrition, improving hosts’ immune systems and protecting hosts against pathogens. In that context, a collection of oyster associated bacteria producing antibacterial compounds have been [...] Read more.
Discovery after discovery, host-associated microbiota reveal a growing list of positive effects on host homeostasis by contributing to host nutrition, improving hosts’ immune systems and protecting hosts against pathogens. In that context, a collection of oyster associated bacteria producing antibacterial compounds have been established to evaluate their role in non-host-derived immunity. Here, we described alterins; potent anti-Gram negative compounds produced by Pseudoalteromonas hCg-6 and hCg-42 isolated from different healthy oyster hemolymph. The strains hCg-6 and hCg-42 produce a set of at least seven antibacterial compounds, ranging from 926 to 982 Da structurally characterized as cyclolipopeptides (CLPs). Alterins share the same cationic heptapeptidic cycle connected via an amido bond to different hydrophobic hydrocarbon tails. Their MICs disclosed a potent antibacterial activity directed against Gram-negative bacteria including oyster and human pathogens that may confer a beneficial defense mechanism to the host but also represents an untapped source of new antibiotics. The alterins’ mechanisms of action have been deciphered: after binding to lipopolysaccharides (LPS), alterins provoke a membrane depolarization and permeabilization leading to bacterial lysis. As hCg-6 and hCg-42 produced a set of natural derivatives, the structure/activity relationship linked to the carbon tail is clarified. We showed that the hydrocarbon tail determines the LPS-binding properties of alterins and consequently their antibacterial activities. Its length and saturation seem to play a major role in this interaction. Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)
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Article
In-Depth In Silico Search for Cuttlefish (Sepia officinalis) Antimicrobial Peptides Following Bacterial Challenge of Haemocytes
Mar. Drugs 2020, 18(9), 439; https://doi.org/10.3390/md18090439 - 24 Aug 2020
Cited by 4 | Viewed by 1879
Abstract
Cuttlefish (Sepia officinalis) haemocytes are potential sources of antimicrobial peptides (AMPs). To study the immune response to Vibrio splendidus and identify new AMPs, an original approach was developed based on a differential transcriptomic study and an in-depth in silico analysis using [...] Read more.
Cuttlefish (Sepia officinalis) haemocytes are potential sources of antimicrobial peptides (AMPs). To study the immune response to Vibrio splendidus and identify new AMPs, an original approach was developed based on a differential transcriptomic study and an in-depth in silico analysis using multiple tools. Two de novo transcriptomes were retrieved from cuttlefish haemocytes following challenge by V. splendidus or not. A first analysis of the annotated transcripts revealed the presence of Toll/NF-κB pathway members, including newly identified factors such as So-TLR-h, So-IKK-h and So-Rel/NF-κB-h. Out of the eight Toll/NF-κB pathway members, seven were found up-regulated following V. splendidus challenge. Besides, immune factors involved in the immune response were also identified and up-regulated. However, no AMP was identified based on annotation or conserved pattern searches. We therefore performed an in-depth in silico analysis of unannotated transcripts based on differential expression and sequence characteristics, using several tools available like PepTraq, a homemade software program. Finally, five AMP candidates were synthesized. Among them, NF19, AV19 and GK28 displayed antibacterial activity against Gram-negative bacteria. Each peptide had a different spectrum of activity, notably against Vibrio species. GK28—the most active peptide—was not haemolytic, whereas NF19 and AV19 were haemolytic at concentrations between 50 and 100 µM, 5 to 10 times higher than their minimum inhibitory concentration. Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)
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Communication
Antimycobacterial Activity of Laurinterol and Aplysin from Laurencia johnstonii
Mar. Drugs 2020, 18(6), 287; https://doi.org/10.3390/md18060287 - 30 May 2020
Cited by 5 | Viewed by 2015
Abstract
Marine environments represent a great opportunity for the discovery of compounds with a wide spectrum of bioactive properties. Due to their large variety and functions derived from natural selection, marine natural products may allow the identification of novel drugs based not only on [...] Read more.
Marine environments represent a great opportunity for the discovery of compounds with a wide spectrum of bioactive properties. Due to their large variety and functions derived from natural selection, marine natural products may allow the identification of novel drugs based not only on newly discovered bioactive metabolites but also on already known compounds not yet thoroughly investigated. Since drug resistance has caused an increase in infections by Mycobacterium tuberculosis and nontuberculous mycobacteria, the re-evaluation of known bioactive metabolites has been suggested as a good approach to addressing this problem. In this sense, this study presents an evaluation of the in vitro effect of laurinterol and aplysin, two brominated sesquiterpenes isolated from Laurencia johnstonii, against nine M. tuberculosis strains and six nontuberculous mycobacteria (NTM). Laurinterol exhibited good antimycobacterial activity, especially against nontuberculous mycobacteria, being remarkable its effect against Mycobacterium abscessus, with minimum inhibitory concentration (MIC) values lower than those of the reference drug imipenem. This study provides further evidence for the antimycobacterial activity of some sesquiterpenes from L. johnstonii, which can be considered interesting lead compounds for the discovery of novel molecules to treat NTM infections. Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)
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Article
A New Citrinin Derivative from the Indonesian Marine Sponge-Associated Fungus Penicillium citrinum
Mar. Drugs 2020, 18(4), 227; https://doi.org/10.3390/md18040227 - 24 Apr 2020
Cited by 15 | Viewed by 3624
Abstract
Sponge-associated fungi are attractive targets for the isolation of bioactive natural products with different pharmaceutical purposes. In this investigation, 20 fungi were isolated from 10 different sponge specimens. One isolate, the fungus Penicillium citrinum strain WK-P9, showed activity against Bacillus subtilis JH642 when [...] Read more.
Sponge-associated fungi are attractive targets for the isolation of bioactive natural products with different pharmaceutical purposes. In this investigation, 20 fungi were isolated from 10 different sponge specimens. One isolate, the fungus Penicillium citrinum strain WK-P9, showed activity against Bacillus subtilis JH642 when cultivated in malt extract medium. One new and three known citrinin derivatives were isolated from the extract of this fungus. The structures were elucidated by 1D and 2D NMR spectroscopy, as well as LC-HRMS. Their antibacterial activity against a set of common human pathogenic bacteria and fungi was tested. Compound 2 showed moderate activity against Mycobacterium smegmatis ATCC607 with a minimum inhibitory concentration (MIC) of 32 µg/mL. Compound 4 exhibited moderate growth inhibition against Bacillus subtilis JH642, B. megaterium DSM32, and M. smegmatis ATCC607 with MICs of 16, 16, and 32 µg/mL, respectively. Furthermore, weak activities of 64 µg/mL against B. subtilis DSM10 and S. aureus ATCC25923 were observed for compound 4. Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)
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Review

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Review
Antibiotics Development and the Potentials of Marine-Derived Compounds to Stem the Tide of Multidrug-Resistant Pathogenic Bacteria, Fungi, and Protozoa
Mar. Drugs 2020, 18(3), 145; https://doi.org/10.3390/md18030145 - 28 Feb 2020
Cited by 21 | Viewed by 4311
Abstract
As the search for new antibiotics continues, the resistance to known antimicrobial compounds continues to increase. Many researchers around the world, in response to antibiotics resistance, have continued to search for new antimicrobial compounds in different ecological niches such as the marine environment. [...] Read more.
As the search for new antibiotics continues, the resistance to known antimicrobial compounds continues to increase. Many researchers around the world, in response to antibiotics resistance, have continued to search for new antimicrobial compounds in different ecological niches such as the marine environment. Marine habitats are one of the known and promising sources for bioactive compounds with antimicrobial potentials against currently drug-resistant strains of pathogenic microorganisms. For more than a decade, numerous antimicrobial compounds have been discovered from marine environments, with many more antimicrobials still being discovered every year. So far, only very few compounds are in preclinical and clinical trials. Research in marine natural products has resulted in the isolation and identification of numerous diverse and novel chemical compounds with potency against even drug-resistant pathogens. Some of these compounds, which mainly came from marine bacteria and fungi, have been classified into alkaloids, lactones, phenols, quinones, tannins, terpenes, glycosides, halogenated, polyketides, xanthones, macrocycles, peptides, and fatty acids. All these are geared towards discovering and isolating unique compounds with therapeutic potential, especially against multidrug-resistant pathogenic microorganisms. In this review, we tried to summarize published articles from 2015 to 2019 on antimicrobial compounds isolated from marine sources, including some of their chemical structures and tests performed against drug-resistant pathogens. Full article
(This article belongs to the Special Issue Marine Antibiotics 2020)
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