Marine Microbial Natural Products Research Articles

Antibiofilm activity of marine microbial natural products: potential peptide- and polyketide-derived molecules from marine microbes toward targeting biofilm-forming pathogens.

Controlling and treating biofilm-related infections is challenging because of the widespread presence of multidrug-resistant microbes. Biofilm, a naturally occurring matrix of microbial aggregates, has developed intricate and diverse resistance mechanisms against many currently used antibiotics. This poses a significant problem, especially for human health, including clinically chronic infectious diseases. Thus, there is an urgent need to search for and develop new and more effective antibiotics. As the marine environment is recognized as a promising reservoir of new biologically active molecules with potential pharmacological properties, marine natural products, particularly those of microbial origin, have emerged as a promising source of antibiofilm agents. Marine microbes represent an untapped source of secondary metabolites with antimicrobial activity. Furthermore, marine natural products, owing to their self-defense mechanisms and adaptation to harsh conditions, encompass a wide range of chemical compounds, including peptides and polyketides, which are primarily found in microbes. These molecules can be exploited to provide novel and unique structures for developing alternative antibiotics as effective antibiofilm agents. This review focuses on the possible antibiofilm mechanism of these marine microbial molecules against biofilm-forming pathogens. It provides an overview of biofilm development, its recalcitrant mode of action, strategies for the development of antibiofilm agents, and their assessments. The review also revisits some selected peptides and polyketides from marine microbes reported between 2016 and 2023, highlighting their moderate and considerable antibiofilm activities. Moreover, their antibiofilm mechanisms, such as adhesion modulation/inhibition targeting biofilm-forming pathogens, quorum sensing intervention and inhibition, and extracellular polymeric substance disruption, are highlighted herein.

Application of Marine Microbial Natural Products in Cosmetics.

As the market size of the cosmetics industry increases, the safety and effectiveness of new products face higher requirements. The marine environment selects for species of micro-organisms with metabolic pathways and adaptation mechanisms different from those of terrestrial organisms, resulting in their natural products exhibiting unique structures, high diversity, and significant biological activities. Natural products are usually safe and non-polluting. Therefore, considerable effort has been devoted to searching for cosmetic ingredients that are effective, safe, and natural for marine micro-organisms. However, marine micro-organisms can be difficult, or impossible, to culture because of their special environmental requirements. Metagenomics technology can help to solve this problem. Moreover, using marine species to produce more green and environmentally friendly products through biotransformation has become a new choice for cosmetic manufacturers. In this study, the natural products of marine micro-organisms are reviewed and evaluated with respect to various cosmetic applications.

Natural products potential of Dictyoceratida sponges-associated micro-organisms.

The marine environment represents one of the most underexplored environments in the world. Marine sponges have a higher taxonomic diversity according to definite environmental conditions. They have been considered interesting sources for bioactive compounds. Dictyoceratida sponges are divided into five families which are widely distributed and habituating different types of micro-organisms. However, some secondary metabolites are probably not produced by the sponges themselves, but rather by their associated micro-organisms. These secondary metabolites are characterized by different chemical structures and consequently different biological activities. This review outlines the reported secondary metabolites from micro-organisms associated with Dictyoceratida sponges and their investigated biological activities from 1991 to 2019. The increasing research studies in this field can play a major role in marine microbial natural products drug discovery in the future.

Bioactive Compounds Isolated from Marine-Derived Microbes in China: 2009-2018.

This review outlines the research that was carried out regarding the isolation of bioactive compounds from marine-derived bacteria and fungi by China-based research groups from 2009–2018, with 897 publications being surveyed. Endophytic organisms featured heavily, with endophytes from mangroves, marine invertebrates, and marine algae making up more than 60% of the microbial strains investigated. There was also a strong focus on fungi as a source of active compounds, with 80% of publications focusing on this area. The rapid increase in the number of publications in the field is perhaps most notable, which have increased more than sevenfold over the past decade, and suggests that China-based researchers will play a major role in marine microbial natural products drug discovery in years to come.

Inhibitory effects of collismycin C and pyrisulfoxin A on particulate matter-induced pulmonary injury

BackgroundInhalation of fine particulate matter (PM2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Marine microbial natural products isolated from microbial culture broths were screened for pulmonary protective effects against PM2.5. Two 2,2′-bipyridine compounds isolated from a red alga-associated Streptomyces sp. MC025—collismycin C (2) and pyrisulfoxin A (5)—were found to inhibit PM2.5-mediated vascular barrier disruption. PurposeTo confirm the inhibitory effects of collismycin C and pyrisulfoxin A on PM2.5-induced pulmonary injury Study designIn this study, we investigated the beneficial effects of collismycin C and pyrisulfoxin A on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. MethodsPermeability, leukocyte migration, proinflammatory protein activation, reactive oxygen species (ROS) generation, and histology were evaluated in PM2.5-treated ECs and mice. ResultsCollismycin C and pyrisulfoxin A significantly scavenged PM2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase as well as activated Akt, which helped in maintaining endothelial integrity, in purified pulmonary endothelial cells. Furthermore, collismycin C and pyrisulfoxin A reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid of PM-treated mice. ConclusionThese data suggested that collismycin C and pyrisulfoxin A might exert protective effects on PM-induced inflammatory lung injury and vascular hyperpermeability.

Marine microbial natural products.

Isolation of diverse chemical compounds from marine organisms implies a promising source of natural products. Oceans cover nearly 70% of the earth’s surface and over 90% of the volume of its crust (1). Marine environment contains a variety of species, many of which have no terrestrial counterparts. Recently, trends in search of new drugs emphasize that marine microorganisms could be potential productive sources of novel secondary metabolites (2). Marine microbial secondary metabolites with chemical diversity and varied bioactivities are gaining wide applications in pharmaceutical and agricultural research (3). Their survival in extreme habitats enables marine microorganisms to develop unique physiological as well as metabolic capabilities, which may not be produced by their terrestrial counterparts. It is reported that the number of bioactive metabolites from marine microorganisms has exponentially increased during the last three decades (4). This diversity has attracted scientists to screen these products to find new medications. Bioactivity profiles of marine metabolites include neurotoxic, antiviral, antitumor, antimicrobial or cytotoxic properties and are of considerable biotechnological interest. So far, more than 30 compounds are in clinical or preclinical trials. Currently, 16 of 20 marine antitumor compounds under clinical trial are derived from microbial sources (5). A few examples are didemnin B (Aplidine™) and thiocoraline used for the treatment of different cancers (6). However, despite interest on metabolites from marine derived microorganisms, researchers encounter some problems; for example, in the study of marine bacteria, only 5% of the marine bacteria observed in marine samples were amenable to be cultured with normal microbiological techniques (7). Moreover, taxonomy of marine bacteria is very poorly defined and fermentation yields are very low and may fall in the range of milligrams per liter in some cases. Nevertheless, criteria separating marine microorganisms from their terrestrial counterparts are not ambiguous; traits that help define some of the more distinct marine microorganisms are their ability to display barophily, halophily and autotrophic growth properties. Moreover, a way essential to distinguish marine and terrestrial microbes is using 16S ribosomal RNA analysis (16S rRNA). Fortunately, microbiologists developed PCR-based screening assays that may increase the screening efficiency for bioactive compounds. In addition, advancement in the knowledge of genes involved in the biosynthesis of secondary metabolites and the knowledge with different biosynthetic systems, allow completely new approaches, such as combinatorial biosynthesis, to discover novel antibiotics and add another source of data for elucidation of metabolites structure (8). Some novel compounds from marine microorganisms are under investigation in preclinical/clinical trials. It appears that marine microbial natural products are going to be the most promising and endless source of drug development. In addition to the aforementioned methods, other innovative approaches such as ribosome engineering and the one strain and many compounds method (OSMAC), would also strongly support marine microbial natural products development. It is believed that marine microbial natural products can be better understood and discovered in the next decade by a combination of both conventional and innovative approaches (9).

Recent Advances in the Discovery and Development of Marine Microbial Natural Products

Marine microbial natural products (MMNPs) have attracted increasing attention from microbiologists, taxonomists, ecologists, agronomists, chemists and evolutionary biologists during the last few decades. Numerous studies have indicated that diverse marine microbes appear to have the capacity to produce an impressive array of MMNPs exhibiting a wide variety of biological activities such as antimicrobial, anti-tumor, anti-inflammatory and anti-cardiovascular agents. Marine microorganisms represent an underexplored reservoir for the discovery of MMNPs with unique scaffolds and for exploitation in the pharmaceutical and agricultural industries. This review focuses on MMNPs discovery and development over the past decades, including innovative isolation and culture methods, strategies for discovering novel MMNPs via routine screenings, metagenomics, genomics, combinatorial biosynthesis, and synthetic biology. The potential problems and future directions for exploring MMNPs are also discussed.

A Tropical Marine Microbial Natural Products Geobibliography as an Example of Desktop Exploration of Current Research Using Web Visualisation Tools

Microbial marine biodiscovery is a recent scientific endeavour developing at a time when information and other technologies are also undergoing great technical strides. Global visualisation of datasets is now becoming available to the world through powerful and readily available software such as Worldwind™, ArcGIS Explorer™ and Google Earth™. Overlaying custom information upon these tools is within the hands of every scientist and more and more scientific organisations are making data available that can also be integrated into these global visualisation tools. The integrated global view that these tools enable provides a powerful desktop exploration tool. Here we demonstrate the value of this approach to marine microbial biodiscovery by developing a geobibliography that incorporates citations on tropical and near-tropical marine microbial natural products research with Google Earth™ and additional ancillary global data sets. The tools and software used are all readily available and the reader is able to use and install the material described in this article.

Identification of Sponge-Associated Bacteria with Antibacterial Property against Staphylococcus aureus based on Molecular Approach

Staphylococcus aureus is among human pathogens which are known to be resistant to almost clinically significant antibiotics that causes a crisis, in the treatment and management of infectious disease, and also presents a clear danger to the future of public health. Recently, invertebrate-associated microorganisms have become the target of the search for marine microbial natural products. Sponge-associated microorganisms are one of the most interesting natural product sources because they produce bioactive natural products including polyketides and nonribosomal peptides. Molecular approach based on 16S rDNA has been very successful in the identification and the search of secondary metabolite-producing microorganisms, particularly by using specific degenerated primers, for the detection of Polyketide Synthases (PKS) and Nonribosomal Peptide Synthetases (NRPS) gene fragments that are essential for the biosynthesis of bioactive products. Four bacterial isolates from sponge Dysidea sp. were found to inhibit the growth of S. aureus . However, only the best two isolates were selected for further identification and screening for the presence of either PKS or NRPS. The results revealed that both isolates BSP5.11 and BSP11.7 have 99% homology with Alpha proteobacterium . PCR analysis of PKS and NRPS gene fragments showed that they both amplified the NRPS but not the PKS gene fragments.

Marine microbial natural products in antifouling coatings

Ecological problems associated with current antifouling technologies have increased interest in the natural strategies that marine organisms use to keep their surfaces clean and free from fouling. Bacteria isolated from living surfaces in the marine environment have been shown to produce chemicals that are potential antifoulants. Active compounds from the cells and culture supernatant of two bacterial strains, FS‐55 and NudMB50–11, isolated from surface of the seaweed, Fucus serratus, and the nudibranch, Archidoris pseudoargus, respectively, were extracted using solid phase extraction. The extracts were combined with acrylic base paint resin and assayed for antifouling activity by measuring their ability to inhibit the growth of fouling bacteria. These formulations were found to be active against fouling bacteria isolated from marine surfaces. The formulation of antifouling paints that incorporate marine microbial natural products is reported here for the first time. This is a significant advance towards the production of an environmentally friendly antifouling paint that utilises a sustainable supply of natural biodegradable compounds.

Biosynthesis of marine natural products: microorganisms and macroalgae.

This review covers the literature published on the biosynthesis of marine microbial and macroalgal natural products over a 10-year period from 1989 through 1998. A companion review covering the same time period on the biosynthesis of natural products from marine macroorganisms will appear at a later date in this journal. An earlier report by Garson published in this journal surveyed the whole field of marine natural product biosynthesis through mid 1988.1 The field through mid 1992 was reviewed elsewhere in an updated report,2 and several reviews covering specific aspects of marine microbial and macroalgal natural product biosynthesis have been published during this period. Reviewed biosynthetic topics include dinoflagellate and algal sterol side chains,3,4 algal oxylipins,5–8 and microalgal metabolites.9,10 Some of the microorganisms discussed in this report are not strictly marine. Bacteria isolated from coastal waters may have originated from terrestrial habitats and washed into the ocean. Many of these bacteria found at the interface of terrestrial and marine environments, especially the actinobacteria, tolerate wide ranges of salinities. The biosynthesis of natural products from freshwater cyanobacteria and microalgae are described for compounds that are structurally related to marine products. The biosynthetic origins of many marine invertebrate-derived natural products are not clear and have been proposed to involve associated microorganisms. A section on symbiotic microorganisms highlights our current knowledge on the involvement of invertebrate-hosted microorganisms in natural product biosynthesis through cellular localization studies. The review is organized on the basis of a similar taxonomic system used in previous marine natural product biosynthesis1, 2 and structure11 reviews. General labeling patterns consistently used throughout this report are outlined in Fig. 1. 2 Marine microorganisms