Marine microorganism-invertebrate assemblages: perspectives to solve the "supply problem" in the initial steps of drug discovery

Profiling Prokaryotic Communities and Aaptamines of Sponge Aaptos suberitoides from Tulamben, Bali

Sponges (Porifera) harbor a diversity of microorganisms that contribute largely to the production a vast array of bioactive compounds. The microorganisms associated with sponge have an important impact on the chemical diversity of the natural products. Herein, our study focuses on an Aaptos suberitoides commonly found in Indonesia. The objective of this study was to investigate the profile of prokaryotic community and the presence of aaptamine metabolites in sponge Aaptos suberitoides. Sponges were collected from two site locations (Liberty Wreck and Drop Off) in Tulamben, Bali. The sponges were identified by barcoding DNA cytochrome oxidase subunit I (COI) gene. The profile of prokaryotic composition was investigated by amplifying the 16S rRNA gene using primers 515f and 806r to target the V4 region. The metabolites were analyzed using LC-MS, and dereplication was done to identify the aaptamines and its derivates. The barcoding DNA of the sponges confirmed the identity of samples as Aaptos suberitoides. The prokaryotic communities of samples A. suberitoides were enriched and dominated by taxa Proteobacteria, Chloroflexi, Actinobacteria, and Acidobacteria. The chemical analysis showed that all sponges produce aaptamine and isoaaptamine except A. suberitoides S2421 produce analog of aaptamines. This is the first report on the profile of prokaryotic community and the aaptamine of tropical marine sponges, A. suberitoides, from Tulamben, Bali.

Deep-Sea Sponges and Corals off the Western Coast of Florida-Intracellular Mechanisms of Action of Bioactive Compounds and Technological Advances Supporting the Drug Discovery Pipeline

The majority of natural products utilized to treat a diverse array of human conditions and diseases are derived from terrestrial sources. In recent years, marine ecosystems have proven to be a valuable resource of diverse natural products that are generated to defend and support their growth. Such marine sources offer a large opportunity for the identification of novel compounds that may guide the future development of new drugs and therapies. Using the National Oceanic and Atmospheric Administration (NOAA) portal, we explore deep-sea coral and sponge species inhabiting a segment of the U.S. Exclusive Economic Zone, specifically off the western coast of Florida. This area spans ~100,000 km2, containing coral and sponge species at sea depths up to 3000 m. Utilizing PubMed, we uncovered current knowledge on and gaps across a subset of these sessile organisms with regards to their natural products and mechanisms of altering cytoskeleton, protein trafficking, and signaling pathways. Since the exploitation of such marine organisms could disrupt the marine ecosystem leading to supply issues that would limit the quantities of bioactive compounds, we surveyed methods and technological advances that are necessary for sustaining the drug discovery pipeline including in vitro aquaculture systems and preserving our natural ecological community in the future. Collectively, our efforts establish the foundation for supporting future research on the identification of marine-based natural products and their mechanism of action to develop novel drugs and therapies for improving treatment regimens of human conditions and diseases.

Aspergillus niger produces lethal compounds against nematodes

BACKGROUND

Aspergillus niger is generally considered safe and is widely used across a broad range of industries from food to pharmaceuticals. The metabolites of some Aspergillus species are effective in killing nematodes. The active ingredients that play a role are citric acid and oxalic acid.

RESULTS

The effective nematocidal metabolite in the fermentation broth of the A. niger Ym16 is a calcium oxalate coordination compound (C2 H2 O4 •2(C2 HO4 )•C2 O4 •4(H2 O)•2(Ca)). The mortality of fermentation broth and compound solution to second-stage juveniles (J2s) of Meloidogyne incognita were 94% (8 h) and 95% (2 h), respectively. The hatching inhibition rates of fermentation broth and compound solution to eggs of M. incognita were 86% (24 h) and 87% (12 h), respectively. Furthermore, the Ym16 strain promoted plant growth.

CONCLUSION

Strain Ym16 and its metabolites should be the first choice for nematode control because it is an effective agent against soil nematodes. © 2023 Society of Chemical Industry.

Unlocking the Potential of Octocoral-Derived Secondary Metabolites against Neutrophilic Inflammatory Response

Inflammation is a critical defense mechanism that is utilized by the body to protect itself against pathogens and other noxious invaders. However, if the inflammatory response becomes exaggerated or uncontrollable, its original protective role is not only demolished but it also becomes detrimental to the affected tissues or even to the entire body. Thus, regulating the inflammatory process is crucial to ensure that it is resolved promptly to prevent any subsequent damage. The role of neutrophils in inflammation has been highlighted in recent decades by a plethora of studies focusing on neutrophilic inflammatory diseases as well as the mechanisms to regulate the activity of neutrophils during the overwhelmed inflammatory process. As natural products have demonstrated promising effects in a wide range of pharmacological activities, they have been investigated for the discovery of new anti-inflammatory therapeutics to overcome the drawbacks of current synthetic agents. Octocorals have attracted scientists as a plentiful source of novel and intriguing marine scaffolds that exhibit many pharmacological activities, including anti-inflammatory effects. In this review, we aim to provide a summary of the neutrophilic anti-inflammatory properties of these marine organisms that were demonstrated in 46 studies from 1995 to the present (April 2023). We hope the present work offers a comprehensive overview of the anti-inflammatory potential of octocorals and encourages researchers to identify promising leads among numerous compounds isolated from octocorals over the past few decades to be further developed into anti-inflammatory therapeutic agents.

Austalide derivative from marine-derived Aspergillus sp. and evaluation of its cytotoxic and ADME/TOPKAT properties

In-depth chemical investigation of an ethyl acetate extract of Aspergillus sp. isolated from the soft coral Sinularia species resulted in the isolation of one new meroterpenoid, austalide Z (1), one known austalide W (2), six known prenylated indole diketopiperazine alkaloids (3-8), and phthalic acid and its ethyl derivative (9-10). The structures were established by means of 1D and 2D NMR (one- and two-dimensional nuclear magnetic resonance) experiments supported by UV analysis and ESI-MS (electrospray ionization mass spectrometry). In vitro cytotoxic evaluation was performed against the Caco-2 cancer cell line using the MTT assay, which showed that the examined compounds had weak to moderate activities, with the new meroterpenoid austalide Z (1) displaying an IC₅₀ value of 51.6 μg mL^-1. ADME/TOPKAT (absorption, distribution, metabolism, excretion, and toxicity) predication performed in silico showed that most of the isolated compounds possessed reasonable pharmacokinetic, pharmacodynamic, and toxicity properties. Thus, it can be concluded that Aspergillus sp. could act as a source of drug leads for cancer prevention with promising pharmacokinetic and pharmacodynamic properties and thus could be incorporated in pharmaceutical dosage forms.

Prioritization of Microorganisms Isolated from the Indian Ocean Sponge Scopalina hapalia Based on Metabolomic Diversity and Biological Activity for the Discovery of Natural Products

Despite considerable advances in medicine and technology, humanity still faces many deadly diseases such as cancer and malaria. In order to find appropriate treatments, the discovery of new bioactive substances is essential. Therefore, research is now turning to less frequently explored habitats with exceptional biodiversity such as the marine environment. Many studies have demonstrated the therapeutic potential of bioactive compounds from marine macro- and microorganisms. In this study, nine microbial strains isolated from an Indian Ocean sponge, Scopalina hapalia, were screened for their chemical potential. The isolates belong to different phyla, some of which are already known for their production of secondary metabolites, such as the actinobacteria. This article aims at describing the selection method used to identify the most promising microorganisms in the field of active metabolites production. The method is based on the combination of their biological and chemical screening, coupled with the use of bioinformatic tools. The dereplication of microbial extracts and the creation of a molecular network revealed the presence of known bioactive molecules such as staurosporin, erythromycin and chaetoglobosins. Molecular network exploration indicated the possible presence of novel compounds in clusters of interest. The biological activities targeted in the study were cytotoxicity against the HCT-116 and MDA-MB-231 cell lines and antiplasmodial activity against Plasmodium falciparum 3D7. Chaetomium globosum SH-123 and Salinispora arenicola SH-78 strains actually showed remarkable cytotoxic and antiplasmodial activities, while Micromonospora fluostatini SH-82 demonstrated promising antiplasmodial effects. The ranking of the microorganisms as a result of the different screening steps allowed the selection of a promising strain, Micromonospora fluostatini SH-82, as a premium candidate for the discovery of new drugs.

Marine Actinomycetes Associated with Stony Corals: A Potential Hotspot for Specialized Metabolites

Microbial secondary metabolites are an important source of antibiotics currently available for combating drug-resistant pathogens. These important secondary metabolites are produced by various microorganisms, including Actinobacteria. Actinobacteria have a colossal genome with a wide array of genes that code for several bioactive metabolites and enzymes. Numerous studies have reported the isolation and screening of millions of strains of actinomycetes from various habitats for specialized metabolites worldwide. Looking at the extent of the importance of actinomycetes in various fields, corals are highlighted as a potential hotspot for untapped secondary metabolites and new bioactive metabolites. Unfortunately, knowledge about the diversity, distribution and biochemistry of marine actinomycetes compared to hard corals is limited. In this review, we aim to summarize the recent knowledge on the isolation, diversity, distribution and discovery of natural compounds from marine actinomycetes associated with hard corals. A total of 11 new species of actinomycetes, representing nine different families of actinomycetes, were recovered from hard corals during the period from 2007 to 2022. In addition, this study examined a total of 13 new compounds produced by five genera of actinomycetes reported from 2017 to 2022 with antibacterial, antifungal and cytotoxic activities. Coral-derived actinomycetes have different mechanisms of action against their competitors.

Nocturnal Acidification: A Coordinating Cue in the Euprymna scolopes-Vibrio fischeri Symbiosis

The Vibrio fischeri–Euprymna scolopes symbiosis has become a powerful model for the study of specificity, initiation, and maintenance between beneficial bacteria and their eukaryotic partner. In this invertebrate model system, the bacterial symbionts are acquired every generation from the surrounding seawater by newly hatched squid. These symbionts colonize a specialized internal structure called the light organ, which they inhabit for the remainder of the host’s lifetime. The V. fischeri population grows and ebbs following a diel cycle, with high cell densities at night producing bioluminescence that helps the host avoid predation during its nocturnal activities. Rhythmic timing of the growth of the symbionts and their production of bioluminescence only at night is critical for maintaining the symbiosis. V. fischeri symbionts detect their population densities through a behavior termed quorum-sensing, where they secrete and detect concentrations of autoinducer molecules at high cell density when nocturnal production of bioluminescence begins. In this review, we discuss events that lead up to the nocturnal acidification of the light organ and the cues used for pre-adaptive behaviors that both host and symbiont have evolved. This host–bacterium cross talk is used to coordinate networks of regulatory signals (such as quorum-sensing and bioluminescence) that eventually provide a unique yet stable environment for V. fischeri to thrive and be maintained throughout its life history as a successful partner in this dynamic symbiosis.

Bioactivity and Biotechnological Overview of Naturally Occurring Compounds from the Dinoflagellate Family Symbiodiniaceae: A Systematic Review

Marine invertebrates are a significant source of biologically active compounds. Recent studies have highlighted the role of microbiota associated with marine invertebrates in the production of bioactive compounds. Corals and sponges are the main marine invertebrates producing bioactive substances, and Symbiodiniaceae dinoflagellates are well-recognized endosymbionts with corals and sponges playing vital functions. The biological properties of Symbiodiniaceae-derived compounds have garnered attention in the past decades owing to their ecological implications and potentiality for bioprospecting initiatives. This study aims to systematically review studies on bioactivities and potential biotechnological applications of Symbiodiniaceae-derived compounds. The PRISMA guidelines were followed. Our study showed that anti-inflammatory and vasoconstrictive activities of Symbiodiniaceae-derived compounds have been the most investigated. However, very few studies have been published, with in vitro culturing of Symbiodiniaceae being the most significant challenge. Therefore, we surveyed for the metabolites reported so far, analyzed their chemodiversity, and discussed approaches to overcome culturing-related limitations.

Pharmacological Activities of Extracts and Compounds Isolated from Mediterranean Sponge Sources

Marine pharmacology is an exciting and growing discipline that blends blue biotechnology and natural compound pharmacology together. Several sea-derived compounds that are approved on the pharmaceutical market were discovered in sponges, marine organisms that are particularly rich in bioactive metabolites. This paper was specifically aimed at reviewing the pharmacological activities of extracts or purified compounds from marine sponges that were collected in the Mediterranean Sea, one of the most biodiverse marine habitats, filling the gap in the literature about the research of natural products from this geographical area. Findings regarding different Mediterranean sponge species were individuated, reporting consistent evidence of efficacy mainly against cancer, infections, inflammatory, and neurological disorders. The sustainable exploitation of Mediterranean sponges as pharmaceutical sources is strongly encouraged to discover new compounds.

On the Path to Thermo-Stable Collagen: Culturing the Versatile Sponge Chondrosia reniformis

The collagen proteins family is sought-after in the pharmaceuticals, cosmetics, and food industries for various biotechnological applications. The most abundant sources of collagen are pigs and cows, but due to religious restrictions and possible disease transmission, they became less attractive. An alternative source can be found in marine invertebrates, specifically in sponges. Alas, two problems arise: (1). Growing sponges is complicated. (2). Sponge collagen has low heat tolerance, which can impose a problem for human biotechnological usage. To fill these gaps, we studied the collagen-abundant sponge Chondrosia reniformis. Two culture experiments were conducted: (1). A sea-based system examined the difference in growth rates of C. reniformis from different habitats, growing under natural seasonal conditions; (2). A land-based controlled system, which assessed the growth-rate of C. reniformis at different temperatures. The results reveal that C. reniformis from shallow habitats are growing larger and faster than individuals from colder, deeper habitats, and that the optimal temperature for C. reniformis growth is 25 °C. The results demonstrate that C. reniformis is highly fit for culture and can produce thermally stable collagen. Further research is needed to determine the best conditions for C. reniformis culture for collagen extract and other exciting materials for bioprospecting.

Existence in cellulose shelters: industrial and pharmaceutical leads of symbiotic actinobacteria from ascidian Phallusia nigra, Andaman Islands

The diversity of actinobacteria associated with marine ascidian Phallusia nigra from Andaman Islands was investigated. A total of 10 actinobacteria were isolated and based on the biochemical and molecular characterization, the isolates were assigned to 7 different actinobacterial genera. Eight putatively novel species belonging to genera Rhodococcus, Kineococcus, Kocuria, Janibacter, Salinispora and Arthrobacter were identified based on 16S rDNA sequence similarity with the NCBI database. The organic extracts of ten isolates displayed considerable bioactivity against test pathogens, which were Gram-positive and Gram-negative in nature. PCR-based screening for type I and type II polyketide synthases (PKS-I, PKS-II) and nonribosomal peptide synthetases (NRPS) revealed that, 10 actinobacterial isolates encoded at least one type of polyketide synthases biosynthesis gene. Majority of the isolates found to produce industrially important enzymes; amylase, protease, gelatinase, lipase, DNase, cellulase, urease, phosphatase and L-asparaginase. The present study emphasized that, ascidians are a prolific resource for novel bioactive actinobacteria with potential for novel drug discovery. This result expands the scope to functionally characterize the novel ascidian associated marine actinobacteria and their metabolites could be a source for the novel molecules of commercial interest.

Marine Natural Products from Tunicates and Their Associated Microbes

Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and anticancer activities. The symbiotic relationship between tunicates and specific microbial groups has revealed the acquisition of microbial compounds by tunicates for defensive purpose. For instance, yellow pigmented compounds, "tambjamines", produced by the tunicate, Sigillina signifera (Sluiter, 1909), primarily originated from their bacterial symbionts, which are involved in their chemical defense function, indicating the ecological role of symbiotic microbial association with tunicates. This review has garnered comprehensive literature on MNPs produced by tunicates and their symbiotic microbionts. Various sections covered in this review include tunicates' ecological functions, biological activities, such as antimicrobial, antitumor, and anticancer activities, metabolic origins, utilization of invasive tunicates, and research gaps. Apart from the literature content, 20 different chemical databases were explored to identify tunicates-derived MNPs. In addition, the management and exploitation of tunicate resources in the global oceans are detailed for their ecological and biotechnological implications.

Taxonomic Composition and Biological Activity of Bacterial Communities Associated with Marine Ascidians from Andaman Islands, India

Marine invertebrates, particularly ascidians, constitute an important source of potential active and biofunctional natural products. The microbial diversity associated with ascidians is little recognized, although these microorganisms play a vital role in marine ecosystems. The objective of this study was to investigate bacterial population diversity in four ascidian samples: Phallusia nigra, Phallusia fumigata, Eudistoma viride, and Rhopalaea macrothorax, collected from the North Bay, Andaman and Nicobar Islands. Microbial strains identified up to the species level revealed 236 distinct species/ribotypes out of 298 bacterial strains. Of 298 ascidian-associated bacteria, 72 isolates belong to the class Gammaproteobacteria and the genus Endozoicomonas. The results from this investigation will contribute a broaden knowledge of microbial diversity associated to marine ascidians, and as a promising source for the discovery of new natural products.

Cultivation of fractionated cells from a bioactive-alkaloid-bearing marine sponge Axinella sp

Sponges are among the most primitive multicellular organisms and well-known as a major source of marine natural products. Cultivation of sponge cells has long been an attractive topic due to the prominent evolutionary and cytological significance of sponges and as a potential approach to supply sponge-derived compounds. Sponge cell culture is carried out through culturing organized cell aggregates called 'primmorphs.' Most research culturing sponge cells has used unfractionated cells to develop primmorphs. In the current study, a tropical marine sponge Axinella sp., which contains the bioactive alkaloids, debromohymenialdisine (DBH), and hymenialdisine (HD), was used to obtain fractionated cells and the corresponding primmorphs. These alkaloids, DBH and HD, reportedly show pharmacological activities for treating osteoarthritis and Alzheimer's disease. Three different cell fractions were obtained, including enriched spherulous cells, large mesohyl cells, and small epithelial cells. These cell fractions were cultivated separately, forming aggregates that later developed into different kinds of primmorphs. The three kinds of primmorphs obtained were compared as regards to appearance, morphogenesis, and cellular composition. Additionally, the amount of alkaloid in the primmorphs-culture system was examined over a 30-d culturing period. During the culturing of enriched spherulous cells and developed primmorphs, the total amount of alkaloid declined notably. In addition, the speculation of alkaloid secretion and some phenomena that occurred during cell culturing are discussed.

Planococcus maritimus ML1206 Isolated from Wild Oysters Enhances the Survival of Caenorhabditis elegans against Vibrio anguillarum

With the widespread occurrence of aquaculture diseases and the broad application of antibiotics, drug-resistant pathogens have increasingly affected aquatic animals’ health. Marine probiotics, which live under high pressure in a saltwater environment, show high potential as a substitute for antibiotics in the field of aquatic disease control. In this study, twenty strains of non-hemolytic bacteria were isolated from the intestine of wild oysters and perch, and a model of Caenorhabditis elegans infected by Vibrio anguillarum was established. Based on the model, ML1206, which showed a 99% similarity of 16S rRNA sequence to Planococcus maritimus, was selected as a potential marine probiotic, with strong antibacterial capabilities and great acid and bile salt tolerance, to protect Caenorhabditis elegans from being damaged by Vibrio anguillarum. Combined with plate counting and transmission electron microscopy, it was found that strain ML1206 could significantly inhibit Vibrio anguillarum colonization in the intestinal tract of Caenorhabditis elegans. Acute oral toxicity tests in mice showed that ML1206 was safe and non-toxic. The real-time qPCR results showed a higher expression level of genes related to the antibacterial peptide (ilys-3) and detoxification (ugt-22, cyp-35A3, and cyp-14A3) in the group of Caenorhabditis elegans protected by ML1206 compared to the control group. It is speculated that ML1206, as a potential probiotic, may inhibit the infection caused by Vibrio anguillarum through stimulating Caenorhabditis elegans to secrete antibacterial effectors and detoxification proteins. This paper provides a new direction for screening marine probiotics and an experimental basis to support the potential application of ML1206 as a marine probiotic in aquaculture.

40 Years of Research on Polybrominated Diphenyl Ethers (PBDEs)-A Historical Overview and Newest Data of a Promising Anticancer Drug

Polybrominated diphenyl ethers (PBDEs) are a group of molecules with an ambiguous background in literature. PBDEs were first isolated from marine sponges of Dysidea species in 1981 and have been under continuous research to the present day. This article summarizes the two research aspects, (i) the marine compound chemistry research dealing with naturally produced PBDEs and (ii) the environmental toxicology research dealing with synthetically-produced brominated flame-retardant PBDEs. The different bioactivity patterns are set in relation to the structural similarities and dissimilarities between both groups. In addition, this article gives a first structure-activity relationship analysis comparing both groups of PBDEs. Moreover, we provide novel data of a promising anticancer therapeutic PBDE (i.e., 4,5,6-tribromo-2-(2',4'-dibromophenoxy)phenol; termed P01F08). It has been known since 1995 that P01F08 exhibits anticancer activity, but the detailed mechanism remains poorly understood. Only recently, Mayer and colleagues identified a therapeutic window for P01F08, specifically targeting primary malignant cells in a low µM range. To elucidate the mechanistic pathway of cell death induction, we verified and compared its cytotoxicity and apoptosis induction capacity in Ramos and Jurkat lymphoma cells. Moreover, using Jurkat cells overexpressing antiapoptotic Bcl-2, we were able to show that P01F08 induces apoptosis mainly through the intrinsic mitochondrial pathway.

Genomics- and Metabolomics-Based Investigation of the Deep-Sea Sediment-Derived Yeast, Rhodotorula mucilaginosa 50-3-19/20B

Red yeasts of the genus Rhodotorula are of great interest to the biotechnological industry due to their ability to produce valuable natural products, such as lipids and carotenoids with potential applications as surfactants, food additives, and pharmaceuticals. Herein, we explored the biosynthetic potential of R. mucilaginosa 50-3-19/20B collected from the Mid-Atlantic Ridge using modern genomics and untargeted metabolomics tools. R. mucilaginosa 50-3-19/20B exhibited anticancer activity when grown on PDA medium, while antimicrobial activity was observed when cultured on WSP-30 medium. Applying the bioactive molecular networking approach, the anticancer activity was linked to glycolipids, namely polyol esters of fatty acid (PEFA) derivatives. We purified four PEFAs (1–4) and the known methyl-2-hydroxy-3-(1H-indol-2-yl)propanoate (5). Their structures were deduced from NMR and HR-MS/MS spectra, but 1–5 showed no anticancer activity in their pure form. Illumina-based genome sequencing, de novo assembly and standard biosynthetic gene cluster (BGC) analyses were used to illustrate key components of the PEFA biosynthetic pathway. The fatty acid producing BGC3 was identified to be capable of producing precursors of PEFAs. Some Rhodotorula strains are able to convert inulin into high-yielding PEFA and cell lipid using a native exo-inulinase enzyme. The genomic locus for an exo-inulinase enzyme (g1629.t1), which plays an instrumental role in the PEFA production via the mannitol biosynthesis pathway, was identified. This is the first untargeted metabolomics study on R. mucilaginosa providing new genomic insights into PEFA biosynthesis.

Composition and geographic variation of the bacterial microbiota associated with the coelomic fluid of the sea urchin Paracentrotus lividus

In the present work, culture-based and culture-independent investigations were performed to determine the microbiota structure of the coelomic fluid of Mediterranean sea urchin Paracentrotus lividus individuals collected from two distinct geographical sites neighboring a high-density population bay and a nature reserve, respectively. Next Generation Sequencing analysis of 16S rRNA gene (rDNA) showed that members of the Proteobacteria, Bacteroidetes and Fusobacteria phyla, which have been previously reported to be commonly retrieved from marine invertebrates, dominate the overall population of microorganisms colonizing this liquid tissue, with minority bacterial genera exhibiting remarkable differences among individuals. Our results showed that there is a correlation between microbiota structure and geographical location of the echinoderm collection site, highlighting over-representation of metagenomic functions related to amino acid and bioactive peptides metabolism in specimens inhabiting the nature reserve. Finally, we also described the developmental delay and aberrations exhibited by sea urchin embryos exposed to distinct bacterial isolates, and showed that these defects rely upon hydrophilic compound(s) synthesized by the bacterial strains assayed. Altogether, our findings lay the groundwork to decipher the relationships of bacteria with sea urchins in their aquatic environment, also providing an additional layer of information to understand the biological roles of the coelomic fluid.

Culture systems influence the physiological performance of the soft coral Sarcophyton glaucum

There is an urgent need to develop means of ex situ biobanking and biopreserving corals and other marine organisms whose habitats have been compromised by climate change and other anthropogenic stressors. To optimize laboratory growth of soft corals in a way that could also benefit industry (e.g., aquarium trade), three culture systems were tested herein with Sarcophyton glaucum: (1) a recirculating aquaculture system (RAS) without exogenous biological input (RAS-B), (2) a RAS with "live" rocks and an exogenous food supply (RAS+B), and (3) a simple flow-through system (FTS) featuring partially filtered natural seawater. In each system, the effects of two levels of photosynthetically active radiation (100 or 200 μmol quanta m^-2 s^-1) and flow velocity (5 or 15 cm s^-1) were assessed, and a number of soft coral response variables were measured. All cultured corals survived the multi-month incubation, yet those of the RAS-B grew slowly and even paled; however, once they were fed (RAS-B modified to RAS+B), their pigmentation increased, and their oral discs readily expanded. Light had a more pronounced effect in the RAS-B system, while flow affected certain coral response variables in the FTS tanks; there were few effects of light or flow in the RAS+B system, potentially highlighting the importance of heterotrophy. Unlike the ceramic pedestals of the FTS, those of the RAS+B did not regularly become biofouled by algae. In concert with the aforementioned physiological findings, we therefore recommend RAS+B systems as a superior means of biopreservating and biobanking soft corals.

Bridging the Gap: Plant-Endophyte Interactions as a Roadmap to Understanding Small-Molecule Communication in Marine Microbiomes

Probing the composition of the microbiome and its association with health and disease states is more accessible than ever due to the rise of affordable sequencing technology. Despite advances in our ability to identify members of symbiont communities, untangling the chemical signaling that they use to communicate with host organisms remains challenging. In order to gain a greater mechanistic understanding of how the microbiome impacts health, and how chemical ecology can be leveraged to advance small-molecule drug discovery from microorganisms, the principals governing communication between host and symbiont must be elucidated. Herein, we review common modes of interkingdom small-molecule communication in terrestrial and marine environments, describe the differences between these environments, and detail the advantages and disadvantages for studies focused on the marine environment. Finally, we propose the use of plant-endophyte interactions as a stepping stone to a greater understanding of similar interactions in marine invertebrates, and ultimately in humans.

Genomics Reveals the Metabolic Potential and Functions in the Redistribution of Dissolved Organic Matter in Marine Environments of the Genus Thalassotalea

Members of the bacterial genus Thalassotalea have been isolated recently from various marine environments, including marine invertebrates. A metagenomic study of the Deepwater Horizon oil plume has identified genes involved in aromatic hydrocarbon degradation in the Thalassotalea genome, shedding light on its potential role in the degradation of crude oils. However, the genomic traits of the genus are not well-characterized, despite the ability of the species to degrade complex natural compounds, such as agar, gelatin, chitin, or starch. Here, we obtained a complete genome of a new member of the genus, designated PS06, isolated from marine sediments containing dead marine benthic macroalgae. Unexpectedly, strain PS06 was unable to grow using most carbohydrates as sole carbon sources, which is consistent with the finding of few ABC transporters in the PS06 genome. A comparative analysis of 12 Thalassotalea genomes provided insights into their metabolic potential (e.g., microaerobic respiration and carbohydrate utilization) and evolutionary stability [including a low abundance of clustered regularly interspaced short palindromic repeats (CRISPR) loci and prophages]. The diversity and frequency of genes encoding extracellular enzymes for carbohydrate metabolism in the 12 genomes suggest that members of Thalassotalea contribute to nutrient cycling by the redistribution of dissolved organic matter in marine environments. Our study improves our understanding of the ecological and genomic properties of the genus Thalassotalea.

Role of symbiosis in the discovery of novel antibiotics

Antibiotic resistance has been an ongoing challenge that has emerged almost immediately after the initial discovery of antibiotics and requires the development of innovative new antibiotics and antibiotic combinations that can effectively mitigate the development of resistance. More than 35,000 people die each year from antibiotic resistant infections in just the United States. This signifies the importance of identifying other alternatives to antibiotics for which resistance has developed. Virtually, all currently used antibiotics can trace their genesis to soil derived bacteria and fungi. The bacteria and fungi involved in symbiosis is an area that still remains widely unexplored for the discovery and development of new antibiotics. This brief review focuses on the challenges and opportunities in the application of symbiotic microbes and also provides an interesting platform that links natural product chemistry with evolutionary biology and ecology.

Four new steroids from the marine soft coral-derived fungus Penicillium sp. SCSIO41201

Penicildiones A-D (1-4), four new steroids derivatives together with three known compounds including 16α-methylpregna-17α,19-dihydroxy-(9,11)-epoxy-4-ene-3,18-dione-20-acetoxy (5), stachybotrylactone B (6) and stachybotrin (7) were isolated from the soft coral-derived fungus Penicillium sp. SCSIO41201, cultured in the 1% NaCl PDB substrate. Their structures were determined through spectroscopic methods and X-ray crystallography. Biological evaluation results revealed that 6 exhibited significant cytotoxic activity against HL-60, K562, MOLT-4, ACHN, 786-O, and OS-RC-2 cell lines with IC₅₀ values of 5.23, 4.12, 4.31, 23.55, 7.65 and 10.81 μmol·L^-1, respectively, while other compounds showed weak or no cytotoxicity at 50 μmol·L^-1.

Pesudomance sp. Bacteria Associated with Marine Sponge as a Promising and Sustainable Source of Bioactive Molecules

BACKGROUND

The study was conducted to identify the bacterial strain associated with marine sponge Hyrtiosaff. erectus collected from the Red Sea coastal water and to assess the utilization of their secondary metabolites for human benefit as antioxidant, anti-Alzheimer, anti-viral, anticancer and anti-inflammatory agent.

METHODS

After biochemical identification of Pesudomance sp. bacterial strain, the total polyphenol contents, cytotoxic, antioxidant, anti-Alzheimer, anti-viral, anticancer and anti-inflammatory activity of the Pesudomance sp. ethyl acetate extract were investigated by applying different biochemical assays. Polyphenol contents were investigated using spectrophotometric techniques. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), and 2,2/-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) ABTS radical scavenging activity assays. The cytotoxic effects were investigated by using the human cancerous cell lines.

RESULTS

The anti-Alzheimer, anti-viral, anticancer and anti-inflammatory activities were determined using ELISA. Qualitative phytochemical analysis of the Pesudomance sp. extract demonstrated the presence of a large and diverse group of substances such as alkaloids, carbohydrates, flavonoids, phenols, terpenoids, saponins, and tannins. The strong antioxidant activity of the Pesudomance sp. extract was mainly attributed to the protective role of polyphenols against reactive oxygen. It was also observed that Pesudomance sp. extract possessed significant anti-Alzheimer activity with 94% at 1 mg. The extract showed also high antiviral activity (90%) using reverse transcriptase enzymes inhibition assay. The examination of the anticancer activity by applying two experimental models, i.e., PTK and SHKI cleared out high significant percentages of 76.19 and 83.09 %; respectively.

CONCLUSION

The anti-inflammatory profiling using TNF, COX1, COX2, IL6 also revealed high antiinflammatory activity with different metabolic pathway of 62.70, 75.444, 79.27 and 54.15 %; respectively. The present study concluded that ethyl acetate extract of Pesudomance sp. possessed strong antioxidant, anti-Alzheimer, and anti-viral, anticancer and anti-inflammatory activities. Further studies are required to purify the bioactive compounds.

Coral and Coral-Associated Microorganisms: A Prolific Source of Potential Bioactive Natural Products

Marine invertebrates and their associated microorganisms are rich sources of bioactive compounds. Among them, coral and its associated microorganisms are promising providers of marine bioactive compounds. The present review provides an overview of bioactive compounds that are produced by corals and coral-associated microorganisms, covering the literature from 2010 to March 2019. Accordingly, 245 natural products that possess a wide range of potent bioactivities, such as anti-inflammatory, cytotoxic, antimicrobial, antivirus, and antifouling activities, among others, are described in this review.

Coral and Coral-Associated Microorganisms: A Prolific Source of Potential Bioactive Natural Products

Marine invertebrates and their associated microorganisms are rich sources of bioactive compounds. Among them, coral and its associated microorganisms are promising providers of marine bioactive compounds. The present review provides an overview of bioactive compounds that are produced by corals and coral-associated microorganisms, covering the literature from 2010 to March 2019. Accordingly, 245 natural products that possess a wide range of potent bioactivities, such as anti-inflammatory, cytotoxic, antimicrobial, antivirus, and antifouling activities, among others, are described in this review.

Integrated Genomic and Metabolomic Approach to the Discovery of Potential Anti-Quorum Sensing Natural Products from Microbes Associated with Marine Samples from Singapore

With 70% of the Earth's surface covered in water, the marine ecosystem offers immense opportunities for drug discovery and development. Due to the decreasing rate of novel natural product discovery from terrestrial sources in recent years, many researchers are beginning to look seaward for breakthroughs in new therapeutic agents. As part of an ongoing marine drug discovery programme in Singapore, an integrated approach of combining metabolomic and genomic techniques were initiated for uncovering novel anti-quorum sensing molecules from bacteria associated with subtidal samples collected in the Singapore Strait. Based on the culture-dependent method, a total of 102 marine bacteria strains were isolated and the identities of selected strains were established based on their 16S rRNA gene sequences. About 5% of the marine bacterial organic extracts showed quorum sensing inhibitory (QSI) activity in a dose-dependent manner based on the Pseudomonas aeruginosa QS reporter system. In addition, the extracts were subjected to mass spectrometry-based molecular networking and the genome of selected strains were analysed for known as well as new biosynthetic gene clusters. This study revealed that using integrated techniques, coupled with biological assays, can provide an effective and rapid prioritization of marine bacterial strains for downstream large-scale culturing for the purpose of isolation and structural elucidation of novel bioactive compounds.

Dalmanol biosyntheses require coupling of two separate polyketide gene clusters

Polyketide–polyketide hybrids are unique natural products with promising bioactivity, but the hybridization processes remain poorly understood.

Polyketide–polyketide hybrids are unique natural products with promising bioactivity, but the hybridization processes remain poorly understood. Herein, we present that the biosynthetic pathways of two immunosuppressants, dalmanol A and acetodalmanol A, result from an unspecific monooxygenase triggered hybridization of two distinct polyketide (naphthalene and chromane) biosynthetic gene clusters. The orchestration of the functional dimorphism of the polyketide synthase (ChrA) ketoreductase (KR) domain (shortened as ChrA KR) with that of the KR partner (ChrB) in the bioassembly line increases the polyketide diversity and allows the fungal generation of plant chromanes (e.g., noreugenin) and phloroglucinols (e.g., 2,4,6-trihydroxyacetophenone). The simultaneous fungal biosynthesis of 1,3,6,8- and 2-acetyl-1,3,6,8-tetrahydroxynaphthalenes was addressed as well. Collectively, the work may symbolize a movement in understanding the multiple-gene-cluster involved natural product biosynthesis, and highlights the possible fungal generations of some chromane- and phloroglucinol-based phytochemicals.

Aglaophenia octodonta (Cnidaria, Hydrozoa) and the Associated Microbial Community: a Cooperative Alliance?

Recently, genetic approaches have revealed a surprising bacterial world as well as a growing knowledge of the enormous distribution of animal-bacterial interactions. In the present study, the diversity of the microorganisms associated to the hydroid Aglaophenia octodonta was studied with epifluorescence, optical, and scanning electron microscopy. Small subunit ribosomal RNA gene sequencing with "universal" and taxon-specific primers allowed the assignment of the microalgae to Symbiodinium and the peritrich ciliates to Pseudovorticella, while the luminous vibrios were identified as Vibrio jasicida of the Harvey clade. To understand the possible relationships among Vibrio jasicida, Symbiodinium, A. octodonta, and Pseudovorticella, specific treatments were conducted in microcosm experiments, with the antibiotic ampicillin and other substances that interfere with bacterial and hydroid metabolism. Treatment of A. octodonta with ampicillin resulted in a decrease of bacterial luminescence followed by Pseudovorticella detachment and Symbiodinium expulsion and suggesting that these microorganisms form a "consortium" with beneficial metabolic interdependence. This hypothesis was reinforced by the evidence that low concentrations of hydrogen peroxide, which stimulate the bacterial oxidative metabolism and luminescence by releasing oxygen, were able to counteract the detrimental effect of ampicillin on the stability of the studied A. octodonta association. A model is proposed in which microalgae that release oxygen during photosynthesis are useful to luminous bacteria for their metabolism and for establishing/maintaining symbiosis leading to a close alliance and mutual benefit of the system A. octodonta-Vibrio jasicida-Pseudovorticella sp.-Symbiodinium sp.

Hyporientalin A, an anti-Candida peptaibol from a marine Trichoderma orientale

A Trichoderma orientale strain LSBA1 was isolated from the Mediterranean marine sponge Cymbaxinella damicornis. The crude extract of T. orientale mycelium showed inhibitory activity against growth of Gram-positive and Gram-negative bacteria as well as clinical isolates of Candida albicans. Purification of the anti-Candida component was performed using a combination of open silica gel-60 column and reverse phase high performance liquid chromatography. The active compound called hyporientalin A has been identified as a peptaibol analogue of longibrachin-A-II using mass spectrometry. It exhibited fungicidal activity against clinical isolates of C. albicans with minimal inhibitory concentrations (MICs) ranging from 2.49 to 19.66 µM, comparable to that of the antifungal agent amphotericin B. Our data support the use of hyporientalin A as a promising new and efficient antifungal drug in the treatment of candidiasis while controlling toxicity.

Marine Invertebrate Natural Products that Target Microtubules

Marine natural products as secondary metabolites are a potential major source of new drugs for treating disease. In some cases, cytotoxic marine metabolites target the microtubules of the eukaryote cytoskeleton for reasons that will be discussed. This review covers the microtubule-targeting agents reported from sponges, corals, tunicates, and molluscs and the evidence that many of these secondary metabolites are produced by bacterial symbionts. The review finishes by discussing the directions for future development and production of clinically relevant amounts of these natural products and their analogues through aquaculture, chemical synthesis, and biosynthesis by bacterial symbionts.

Two new hirsutane-type sesquiterpenoids chondrosterins N and O from the marine fungus Chondrostereum sp

The marine fungus Chondrostereum sp. was collected from a soft coral Sarcophyton tortuosum from the South China Sea. This fungus was cultured in glucose-peptone-yeast (GPY) medium and the culture broth was extracted with EtOAc. By the method of ¹H NMR pre-screening and tracing the diagnostic proton signals of the methyl groups, two new hirsutane-type sesquiterpenoids, chondrosterins N and O (1 and 2) were isolated from the metabolite extracts. Their structures were elucidated on the basis of MS, 1D and 2D NMR data.

Pseudoalteromone C: A Novel Ubichromenol Derivative from Bacterium Pseudoalteromonas sp. CGH2XX Isolated from the Cultured-type Octocoral Lobophytum crassum

A novel ubichromenol derivative, pseudoalteromone C (1), possessing a 9C nor-monoterpenoid moiety was produced from CGH2XX, a Pseudoaltermonas sp. strain that was originally cloned from bacteria communities associated with the cultured-type octocoral Lobophytum crassum. The structure of 1 was elucidated by using spectroscopic methods and comparing the spectroscopic data with those of known related metabolites.

A Novel Brominated Alkaloid Securidine A, Isolated from the Marine Bryozoan Securiflustra securifrons

A novel brominated alkaloid, Securidine A, was isolated from the cold water marine bryozoan Securiflustra securifrons. Securidine A was isolated using semi-preparative HPLC, and the structure was elucidated by spectroscopic methods. The isolated Securidine A was tested for cytotoxic, antibacterial, and anti-diabetic activities as well as for its potential for inhibition of biofilm formation. No significant biological activity was observed in the applied bioassays, thus expanded bioactivity profiling is required, in order to reveal any potential applications for Securidine A.

Symbiosis-inspired approaches to antibiotic discovery

Covering: 2010 up to 2017Life on Earth is characterized by a remarkable abundance of symbiotic and highly refined relationships among life forms. Defined as any kind of close, long-term association between two organisms, symbioses can be mutualistic, commensalistic or parasitic. Historically speaking, selective pressures have shaped symbioses in which one organism (typically a bacterium or fungus) generates bioactive small molecules that impact the host (and possibly other symbionts); the symbiosis is driven fundamentally by the genetic machineries available to the small molecule producer. The human microbiome is now integral to the most recent chapter in animal-microbe symbiosis studies and plant-microbe symbioses have significantly advanced our understanding of natural products biosynthesis; this also is the case for studies of fungal-microbe symbioses. However, much less is known about microbe-microbe systems involving interspecies interactions. Microbe-derived small molecules (i.e. antibiotics and quorum sensing molecules, etc.) have been shown to regulate transcription in microbes within the same environmental niche, suggesting interspecies interactions whereas, intraspecies interactions, such as those that exploit autoinducing small molecules, also modulate gene expression based on environmental cues. We, and others, contend that symbioses provide almost unlimited opportunities for the discovery of new bioactive compounds whose activities and applications have been evolutionarily optimized. Particularly intriguing is the possibility that environmental effectors can guide laboratory expression of secondary metabolites from "orphan", or silent, biosynthetic gene clusters (BGCs). Notably, many of the studies summarized here result from advances in "omics" technologies and highlight how symbioses have given rise to new anti-bacterial and antifungal natural products now being discovered.

Producing Novel Fibrinolytic Isoindolinone Derivatives in Marine Fungus Stachybotrys longispora FG216 by the Rational Supply of Amino Compounds According to Its Biosynthesis Pathway

Many fungi in the Stachybotrys genus can produce various isoindolinone derivatives. These compounds are formed by a spontaneous reaction between a phthalic aldehyde precursor and an ammonium ion or amino compounds. In this study, we suggested the isoindolinone biosynthetic gene cluster in Stachybotrys by genome mining based on three reported core genes. Remarkably, there is an additional nitrate reductase (NR) gene copy in the proposed cluster. NR is the rate-limiting enzyme of nitrate reduction. Accordingly, this cluster was speculated to play a role in the balance of ammonium ion concentration in Stachybotrys. Ammonium ions can be replaced by different amino compounds to create structural diversity in the biosynthetic process of isoindolinone. We tested a rational supply of amino compounds ((±)-3-amino-2-piperidinone, glycine, and l-threonine) in the culture of an isoindolinone high-producing marine fungus, Stachybotrys longispora FG216. As a result, we obtained four new kinds of isoindolinone derivatives (FGFC4–GFC7) by this method. Furthermore, high yields of FGFC4–FGFC7 confirmed the outstanding production capacity of FG216. Among the four new isoindolinone derivatives, FGFC6 and FGFC7 showed promising fibrinolytic activities. The knowledge of biosynthesis pathways may be an important attribute for the discovery of novel bioactive marine natural products.

Identification and bioactive potential of marine microorganisms from selected Florida coastal areas

The ocean, with its rich untapped chemical biodiversity, continues to serve as a source of potentially new therapeutic agents. The evaluation of the diversity of cultivable microorganisms from the marine sponge Halichondria panicea and ocean sediment samples were examined and their potential as sources of antimicrobial and antiproliferative agents were investigated. The marine sponge and sediments were collected at different depths (0.9–6 meters) and locations in Florida, including Florida Keys, Port St. Joe in Pensacola, Pensacola Bay, Pensacola Beach, and Fort Pickens. Twenty‐one cultivatable isolates were grouped according to their morphology and identified using 16S rRNA molecular taxonomy. The bacterial community identified consisted of members belonging to the Actinobacteria, Bacteroidetes, Proteobacteria (Alpha‐ and Gamma‐classes) and Firmicutes phylogeny. Seven of the microbes exhibited mild to significant cytotoxic activities against five microbial indicators but no significant cytotoxic activities were observed against the pancreatic (PANC‐1) nor the multidrug‐resistant ovarian cancer cell lines (NCI/ADR). This work reaffirms the phyla Actinobacteria and Proteobacteria as sources of potential bioactive natural product candidates for drug discovery and development.

Natural and Synthetic Coral Biomineralization for Human Bone Revitalization

Coral skeletons can regenerate replacement human bone in nonload-bearing excavated skeletal locations. A combination of multiscale, interconnected pores and channels and highly bioactive surface chemistry has established corals as an important alternative to using healthy host bone replacements. Here, we highlight how coral skeletal systems are being remolded into new calcified structures or synthetic corals by biomimetic processes, as places for the organized permeation of bone tissue cells and blood vessels. Progressive technologies in coral aquaculture and self-organization inorganic chemistry are helping to modify natural corals and create synthetic coral architectures able to accelerate bone regeneration with proper host integration at more skeletal locations, adapted to recent surgical techniques and used to treat intrinsic skeletal deformities and metabolic conditions.

The role of cell replacement in benthic-pelagic coupling by suspension feeders

Benthic-pelagic coupling through suspension feeders and their detrital pathways is integral to carbon transport in oceans. In food-poor ecosystems however, a novel mechanism of carbon recycling has been proposed that involves direct uptake of dissolved carbon by suspension feeders followed by shedding of cells as particulate carbon. We studied cell replacement rates in a range of cold-water sponge species to determine how universal this mechanism might be. We show that cell replacement rates of feeding epithelia in explants vary from 30 hours up to 7 days, and change during different seasons and life-history stages. We also found that feeding epithelia are not replaced through direct replication but instead arise from a population of stem cells that differentiate and integrate into epithelial tissues. Our results reveal a surprising amount of complexity in the control of cell processes in sponges, with cell turnover depending on environmental conditions and using stem cells as rate-limiting mechanisms. Our results also suggest that for species in cold water with high particulate organic matter, cell turnover is not the mechanism delivering carbon flux to surrounding communities.

The role of cell replacement in benthic-pelagic coupling by suspension feeders

Benthic-pelagic coupling through suspension feeders and their detrital pathways is integral to carbon transport in oceans. In food-poor ecosystems however, a novel mechanism of carbon recycling has been proposed that involves direct uptake of dissolved carbon by suspension feeders followed by shedding of cells as particulate carbon. We studied cell replacement rates in a range of cold-water sponge species to determine how universal this mechanism might be. We show that cell replacement rates of feeding epithelia in explants vary from 30 hours up to 7 days, and change during different seasons and life-history stages. We also found that feeding epithelia are not replaced through direct replication but instead arise from a population of stem cells that differentiate and integrate into epithelial tissues. Our results reveal a surprising amount of complexity in the control of cell processes in sponges, with cell turnover depending on environmental conditions and using stem cells as rate-limiting mechanisms. Our results also suggest that for species in cold water with high particulate organic matter, cell turnover is not the mechanism delivering carbon flux to surrounding communities.

The role of sponge-bacteria interactions: the sponge Aplysilla rosea challenged by its associated bacterium Streptomyces ACT-52A in a controlled aquarium system

Sponge-associated bacteria play a critical role in sponge biology, metabolism and ecology, but how they interact with their host sponges and the role of these interactions are poorly understood. This study investigated the role of the interaction between the sponge Aplysilla rosea and its associated actinobacterium, Streptomyces ACT-52A, in modifying sponge microbial diversity, metabolite profile and bioactivity. A recently developed experimental approach that exposes sponges to bacteria of interest in a controlled aquarium system was improved by including the capture and analysis of secreted metabolites by the addition of an absorbent resin in the seawater. In a series of controlled aquaria, A. rosea was exposed to Streptomyces ACT-52A at 10⁶ cfu/ml and monitored for up to 360 h. Shifts in microbial communities associated with the sponges occurred within 24 to 48 h after bacterial exposure and continued until 360 h, as revealed by TRFLP. The metabolite profiles of sponge tissues also changed substantially as the microbial community shifted. Control sponges (without added bacteria) and Streptomyces ACT-52A-exposed sponges released different metabolites into the seawater that was captured by the resin. The antibacterial activity of compounds collected from the seawater increased at 96 and 360 h of exposure for the treated sponges compared to the control group due to new compounds being produced and released. Increased antibacterial activity of metabolites from treated sponge tissue was observed only at 360 h, whereas that of control sponge tissue remained unchanged. The results demonstrate that the interaction between sponges and their associated bacteria plays an important role in regulating secondary metabolite production.

A new view on the codonocarpine type alkaloids of Capparis decidua

Several spermidine alkaloids are described in literature as constituents of the root bark of Capparis decidua. Since some of the proposed structures, however, are in conflict with the expected biosynthetic paths, an extract of the root bark of the plant was re-investigated. Four major spermidine alkaloids of the codonocarpine type were identified and their structures elucidated: of the four compounds, isocodonocarpine was described previously for C. decidua and cadabicine was proposed as a possible constituent as well. Codonocarpine was found for the first time in an extract of C. decidua but was previously isolated from a closely related plant. Capparidisinine, finally, is an alkaloid with a structure that has never been described before. The structures of the four alkaloids are substantiated by NMR and MS data, and the four compounds are in logical agreement with biosynthetic considerations: they would arise from α,ω-bis-adducts of spermidine with coumaric and/or ferulic acids, followed by phenol oxidation.

Polyketides in Aspergillus terreus: biosynthesis pathway discovery and application

The knowledge of biosynthesis gene clusters, production improving methods, and bioactivity mechanisms is very important for the development of filamentous fungi metabolites. Metabolic engineering and heterologous expression methods can be applied to improve desired metabolite production, when their biosynthesis pathways have been revealed. And, stable supplement is a necessary basis of bioactivity mechanism discovery and following clinical trial. Aspergillus terreus is an outstanding producer of many bioactive agents, and a large part of them are polyketides. In this review, we took polyketides from A. terreus as examples, focusing on 13 polyketide synthase (PKS) genes in A. terreus NIH 2624 genome. The biosynthesis pathways of nine PKS genes have been reported, and their downstream metabolites are lovastatin, terreic acid, terrein, geodin, terretonin, citreoviridin, and asperfuranone, respectively. Among them, lovastatin is a well-known hypolipidemic agent. Terreic acid, terrein, citreoviridin, and asperfuranone show good bioactivities, especially anticancer activities. On the other hand, geodin and terretonin are mycotoxins. So, biosynthesis gene cluster information is important for the production or elimination of them. We also predicted three possible gene clusters that contain four PKS genes by homologous gene alignment with other Aspergillus strains. We think that this is an effective way to mine secondary metabolic gene clusters.