Photoprotective Bioactivity Present in a Unique Marine Bacteria Collection from Portuguese Deep Sea Hydrothermal Vents

Interesting biological activities have been found for numerous marine compounds. In fact, screening of phylogenetically diverse marine microorganisms from extreme environments revealed to be a rational approach for the discovery of novel molecules with relevant bioactivities for industries such as pharmaceutical and cosmeceutical. Nevertheless, marine sources deliverables are still far from the expectations and new extreme sources of microbes should be explored. In this work, a marine prokaryotic collection from four Mid-Atlantic Ridge (MAR) deep sea hydrothermal vents near the Azores Islands, Portugal, was created, characterized and tested for its photoprotective capacity. Within 246 isolates, a polyphasic approach, using chemotaxonomic and molecular typing methods, identified 23-related clusters of phenetically similar isolates with high indexes of diversity. Interestingly, 16S rRNA gene sequencing suggested the presence of 43% new prokaryotic species. A sub-set of 139 isolates of the prokaryotic collection was selected for biotechnological exploitation with 484 bacterial extracts prepared in a sustainable upscalling manner. 22% of the extracts showed an industrially relevant photoprotective activity, with two extracts, belonging to new strains of the species Shewanella algae and Vibrio fluvialis, uniquely showing UV-A, UV-B and UV-C protective capacity. This clearly demonstrates the high potential of the bacteria MAR vents collection in natural product synthesis with market applications.     

Overview on Biological Activities and Molecular Characteristics of Sulfated Polysaccharides from Marine Green Algae in Recent Years

Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits.     

Marine Polysaccharides as a Versatile Biomass for the Construction of Nano Drug Delivery Systems

Marine biomass is a treasure trove of materials. Marine polysaccharides have the characteristics of biocompatibility, biodegradability, non-toxicity, low cost, and abundance. An enormous variety of polysaccharides can be extracted from marine organisms such as algae, crustaceans, and microorganisms. The most studied marine polysaccharides include chitin, chitosan, alginates, hyaluronic acid, fucoidan, carrageenan, agarose, and Ulva. Marine polysaccharides have a wide range of applications in the field of biomedical materials, such as drug delivery, tissue engineering, wound dressings, and sensors. The drug delivery system (DDS) can comprehensively control the distribution of drugs in the organism in space, time, and dosage, thereby increasing the utilization efficiency of drugs, reducing costs, and reducing toxic side effects. The nano-drug delivery system (NDDS), due to its small size, can function at the subcellular level in vivo. The marine polysaccharide-based DDS combines the advantages of polysaccharide materials and nanotechnology, and is suitable as a carrier for different pharmaceutical preparations. This review summarizes the advantages and drawbacks of using marine polysaccharides to construct the NDDS and describes the preparation methods and modification strategies of marine polysaccharide-based nanocarriers.     

Agarose-Degrading Characteristics of a Deep-Sea Bacterium Vibrio Natriegens WPAGA4 and Its Cold-Adapted GH50 Agarase Aga3420

Up until now, the characterizations of GH50 agarases from Vibrio species have rarely been reported compared to GH16 agarases. In this study, a deep-sea strain, WPAGA4, was isolated and identified as Vibrio natriegens due to the maximum similarity of its 16S rRNA gene sequence, the values of its average nucleotide identity, and through digital DNA–DNA hybridization. Two circular chromosomes in V. natriegens WPAGA4 were assembled. A total of 4561 coding genes, 37 rRNA, 131 tRNA, and 59 other non-coding RNA genes were predicted in the genome of V. natriegens WPAGA4. An agarase gene belonging to the GH50 family was annotated in the genome sequence and expressed in E. coli cells. The optimum temperature and pH of the recombinant Aga3420 (rAga3420) were 40 °C and 7.0, respectively. Neoagarobiose (NA2) was the only product during the degradation process of agarose by rAga3420. rAga3420 had a favorable stability following incubation at 10–30 °C for 50 min. The Km, Vmax, and kcat values of rAga3420 were 2.8 mg/mL, 78.1 U/mg, and 376.9 s⁻¹, respectively. rAga3420 displayed cold-adapted properties as 59.7% and 41.2% of the relative activity remained at 10 3 °C and 0 °C, respectively. This property ensured V. natriegens WPAGA4 could degrade and metabolize the agarose in cold deep-sea environments and enables rAga3420 to be an appropriate industrial enzyme for NA2 production, with industrial potential in medical and cosmetic fields.     

Biological Activities of Ethanolic Extracts from Deep-Sea Antarctic Marine Sponges

We report on the screening of ethanolic extracts from 33 deep-sea Antarctic marine sponges for different biological activities. We monitored hemolysis, inhibition of acetylcholinesterase, cytotoxicity towards normal and transformed cells and growth inhibition of laboratory, commensal and clinically and ecologically relevant bacteria. The most prominent activities were associated with the extracts from sponges belonging to the genus Latrunculia, which show all of these activities. While most of these activities are associated to already known secondary metabolites, the extremely strong acetylcholinesterase inhibitory potential appears to be related to a compound unknown to date. Extracts from Tetilla leptoderma, Bathydorus cf. spinosus, Xestospongia sp., Rossella sp., Rossella cf. racovitzae and Halichondria osculum were hemolytic, with the last two also showing moderate cytotoxic potential. The antibacterial tests showed significantly greater activities of the extracts of these Antarctic sponges towards ecologically relevant bacteria from sea water and from Arctic ice. This indicates their ecological relevance for inhibition of bacterial microfouling.     

Hydrolysis of Fucoidan by Fucoidanase Isolated from the Marine Bacterium,Formosa algae

Intracellular fucoidanase was isolated from the marine bacterium, Formosa algae strain KMM 3553. The first appearance of fucoidan enzymatic hydrolysis products in a cell-free extract was detected after 4 h of bacterial growth, and maximal fucoidanase activity was observed after 12 h of growth. The fucoidanase displayed maximal activity in a wide range of pH values, from 6.5 to 9.1. The presence of Mg²⁺, Ca²⁺ and Ba²⁺ cations strongly activated the enzyme; however, Cu²⁺ and Zn²⁺ cations had inhibitory effects on the enzymatic activity. The enzymatic activity of fucoidanase was considerably reduced after prolonged (about 60 min) incubation of the enzyme solution at 45 °C. The fucoidanase catalyzed the hydrolysis of fucoidans from Fucus evanescens and Fucus vesiculosus, but not from Saccharina cichorioides. The fucoidanase also did not hydrolyze carrageenan. Desulfated fucoidan from F. evanescens was hydrolysed very weakly in contrast to deacetylated fucoidan, which was hydrolysed more actively compared to the native fucoidan from F. evanescens. Analysis of the structure of the enzymatic products showed that the marine bacteria, F. algae, synthesized an α-l-fucanase with an endo-type action that is specific for 1→4-bonds in a polysaccharide molecule built up of alternating three- and four-linked α-l-fucopyranose residues sulfated mainly at position 2.     

Bioactivity and Applications of Sulphated Polysaccharides from Marine Microalgae

Marine microalgae have been used for a long time as food for humans, such as Arthrospira (formerly, Spirulina), and for animals in aquaculture. The biomass of these microalgae and the compounds they produce have been shown to possess several biological applications with numerous health benefits. The present review puts up-to-date the research on the biological activities and applications of polysaccharides, active biocompounds synthesized by marine unicellular algae, which are, most of the times, released into the surrounding medium (exo- or extracellular polysaccharides, EPS). It goes through the most studied activities of sulphated polysaccharides (sPS) or their derivatives, but also highlights lesser known applications as hypolipidaemic or hypoglycaemic, or as biolubricant agents and drag-reducers. Therefore, the great potentials of sPS from marine microalgae to be used as nutraceuticals, therapeutic agents, cosmetics, or in other areas, such as engineering, are approached in this review.     

Gene Cloning,Expression and Characterization of a Novel Xylanase from the Marine Bacterium,Glaciecola mesophila KMM241

Marine xylanases are rather less studied compared to terrestrial xylanases. In this study, a new xylanase gene, xynB, was cloned from the marine bacterium, Glaciecola mesophila KMM241, and expressed in Escherichia coli. xynB encodes a multi-domain xylanase XynB of glycoside hydrolase (GH) family 8. The recombinant XynB comprises an N-terminal domain (NTD) with unknown function and a catalytic domain, which is structurally novel among the characterized xylanases of GH family 8. XynB has the highest identity (38%) to rXyn8 among the characterized xylanases. The recombinant XynB showed maximal activity at pH 6–7 and 35 °C. It is thermolabile and salt-tolerant. XynB is an endo-xylanase that demands at least five sugar moieties for effective cleavage and to hydrolyze xylohexaose and xylopentaose into xylotetraose, xylotriose and xylobiose. NTD was expressed in Escherichia coli to analyze its function. The recombinant NTD exhibited a high binding ability to insoluble xylan and avicel and little binding ability to chitosan and chitin. Since the NTD shows no obvious homology to any known carbohydrate-binding module (CBM) sequence in public databases, XynB may contain a new type of CBM.     

Antiparasitic Effects of Sulfated Polysaccharides from Marine Hydrobionts

This review presents materials characterizing sulfated polysaccharides (SPS) of marine hydrobionts (algae and invertebrates) as potential means for the prevention and treatment of protozoa and helminthiasis. The authors have summarized the literature on the pathogenetic targets of protozoa on the host cells and on the antiparasitic potential of polysaccharides from red, brown and green algae as well as certain marine invertebrates. Information about the mechanisms of action of these unique compounds in diseases caused by protozoa has also been summarized. SPS is distinguished by high antiparasitic activity, good solubility and an almost complete absence of toxicity. In the long term, this allows for the consideration of these compounds as effective and attractive candidates on which to base drugs, biologically active food additives and functional food products with antiparasitic activity.     

Ammonificins C and D, Hydroxyethylamine Chromene Derivatives from a Cultured Marine Hydrothermal Vent Bacterium, Thermovibrio ammonificans

Chemical and biological investigation of the cultured marine hydrothermal vent bacterium, Thermovibrio ammonifican led to the isolation of two hydroxyethylamine chromene derivatives, ammonificins C and D. Their structures were elucidated using combination of NMR and mass spectrometry. Absolute stereochemistry was ascertained by comparison of experimental and calculated CD spectra. Biological evaluation and assessment were determined using the patented ApopScreen cell-based screen for apoptosis-induction. Ammonificins C and D induce apoptosis in micromolar concentrations. To our knowledge, this finding is the first report of chemical compounds that induce apoptosis from the cultured deep-sea marine organism, hydrothermal vent bacterium, Thermovibrio ammonificans.     

Impact of Co-Culture on the Metabolism of Marine Microorganisms

Natural products from plants have been listed for hundreds of years as a source of biologically active molecules. In recent years, the marine environment has demonstrated its ability to provide new structural entities. More than 70% of our planet’s surface is covered by oceans, and with the technical advances in diving and remotely operated vehicles, it is becoming easier to collect samples. Although the risk of rediscovery is significant, the discovery of silent gene clusters and innovative analytical techniques has renewed interest in natural product research. Different strategies have been proposed to activate these silent genes, including co-culture, or mixed fermentation, a cultivation-based approach. This review highlights the potential of co-culture of marine microorganisms to induce the production of new metabolites as well as to increase the yields of respective target metabolites with pharmacological potential, and moreover to indirectly improve the biological activity of a crude extract.     

Amycolachromones A–F,Isolated from a Streptomycin-Resistant Strain of the Deep-Sea Marine Actinomycete Amycolatopsis sp. WP1

In this study, a detailed chemical investigation of a streptomycin-resistant strain of the deep-sea marine, actinomycete Amycolatopsis sp. WP1, yielded six novel amycolachromones A–F (1–6), together with five known analogues (7–11). Amycolachromones A–B (1–2) possessed unique dimer skeletons. The structures and relative configurations of compounds 1–11 were elucidated by extensive spectroscopic data analyses combined with X-ray crystal diffraction analysis. Plausible biogenetic pathways of amycolachromones A–F were also proposed.     

A New Micromonospora Strain with Antibiotic Activity Isolated from the Microbiome of a Mid-Atlantic Deep-Sea Sponge

To tackle the growing problem of antibiotic resistance, it is essential to identify new bioactive compounds that are effective against resistant microbes and safe to use. Natural products and their derivatives are, and will continue to be, an important source of these molecules. Sea sponges harbour a diverse microbiome that co-exists with the sponge, and these bacterial communities produce a rich array of bioactive metabolites for protection and resource competition. For these reasons, the sponge microbiota constitutes a potential source of clinically relevant natural products. To date, efforts in bioprospecting for these compounds have focused predominantly on sponge specimens isolated from shallow water, with much still to be learned about samples from the deep sea. Here we report the isolation of a new Micromonospora strain, designated 28ISP2-46^T, recovered from the microbiome of a mid-Atlantic deep-sea sponge. Whole-genome sequencing reveals the capacity of this bacterium to produce a diverse array of natural products, including kosinostatin and isoquinocycline B, which exhibit both antibiotic and antitumour properties. Both compounds were isolated from 28ISP2-46^T fermentation broths and were found to be effective against a plethora of multidrug-resistant clinical isolates. This study suggests that the marine production of isoquinocyclines may be more widespread than previously supposed and demonstrates the value of targeting the deep-sea sponge microbiome as a source of novel microbial life with exploitable biosynthetic potential.     

Ferroptosis Related Immunomodulatory Effect of a Novel Extracellular Polysaccharides from Marine Fungus Aureobasidium melanogenum

Marine fungi represent an important and sustainable resource, from which the search for novel biological substances for application in the pharmacy or food industry offers great potential. In our research, novel polysaccharide (AUM-1) was obtained from marine Aureobasidium melanogenum SCAU-266 were obtained and the molecular weight of AUM-1 was determined to be 8000 Da with 97.30% of glucose, 1.9% of mannose, and 0.08% galactose, owing to a potential backbone of α-D-Glcp-(1→2)-α-D-Manp-(1→4)-α-D-Glcp-(1→6)-(SO₃⁻)-4-α-D-Glcp-(1→6)-1-β-D-Glcp-1→2)-α-D-Glcp-(1→6)-β-D-Glcp-1→6)-α-D-Glcp-1→4)-α-D-Glcp-6→1)-[α-D-Glcp-4]₂₆→1)-α-D-Glcp and two side chains that consisted of α-D-Glcp-1 and α-D-Glcp-(1→6)-α-D-Glcp residues. The immunomodulatory effect of AUM-1 was identified. Then, the potential molecular mechanism by which AUM-1 may be connected to ferroptosis was indicated by metabonomics, and the expression of COX2, SLC7A11, GPX4, ACSL4, FTH1, and ROS were further verified. Thus, we first speculated that AUM-1 has a potential effect on the ferroptosis-related immunomodulatory property in RAW 264.7 cells by adjusting the expression of GPX4, regulated glutathione (oxidative), directly causing lipid peroxidation owing to the higher ROS level through the glutamate metabolism and TCA cycle. Thus, the ferroptosis related immunomodulatory effect of AUM-1 was obtained.     

Continuous Production of Biogenic Magnetite Nanoparticles by the Marine Bacterium Magnetovibrio blakemorei Strain MV-1T with a Nitrous Oxide Injection Strategy

Magnetotactic bacteria (MTB) produce magnetosomes, which are membrane-embedded magnetic nanoparticles. Despite their technological applicability, the production of magnetite magnetosomes depends on the cultivation of MTB, which results in low yields. Thus, strategies for the large-scale cultivation of MTB need to be improved. Here, we describe a new approach for bioreactor cultivation of Magnetovibrio blakemorei strain MV-1^T. Firstly, a fed-batch with a supplementation of iron source and N₂O injection in 24-h pulses was established. After 120 h of cultivation, the production of magnetite reached 24.5 mg∙L⁻¹. The maximum productivity (16.8 mg∙L⁻¹∙day⁻¹) was reached between 48 and 72 h. However, the productivity and mean number of magnetosomes per cell decreased after 72 h. Therefore, continuous culture in the chemostat was established. In the continuous process, magnetite production and productivity were 27.1 mg∙L⁻¹ and 22.7 mg∙L⁻¹∙day⁻¹, respectively, at 120 h. This new approach prevented a decrease in magnetite production in comparison to the fed-batch strategy.     

Acetylcholinesterase-Inhibiting Activity of Pyrrole Derivatives from a Novel Marine Gliding Bacterium, Rapidithrix thailandica

Acetylcholinesterase-inhibiting activity of marinoquinoline A (1), a new pyrroloquinoline from a novel species of a marine gliding bacterium Rapidithrix thailandica, was assessed (IC₅₀ 4.9 μM). Two related pyrrole derivatives, 3-(2′-aminophenyl)-pyrrole (3) and 2,2-dimethyl-pyrrolo-1,2-dihydroquinoline (4), were also isolated from two other strains of R. thailandica. The isolation of 3 from a natural source is reported here for the first time. Compound 4 was proposed to be an isolation artifact derived from 3. The two isolated compounds were virtually inactive in the acetylcholinesterase-inhibitory assay (enzyme inhibition < 30% at 0.1 g L⁻¹).     

In-Depth Analysis of Exoproteomes from Marine Bacteria by Shotgun Liquid Chromatography-Tandem Mass Spectrometry: the Ruegeria pomeroyi DSS-3 Case-Study

Microorganisms secrete into their extracellular environment numerous compounds that are required for their survival. Many of these compounds could be of great interest for biotechnology applications and their genes used in synthetic biology design. The secreted proteins and the components of the translocation systems themselves can be scrutinized in-depth by the most recent proteomic tools. While the secretomes of pathogens are well-documented, those of non-pathogens remain largely to be established. Here, we present the analysis of the exoproteome from the marine bacterium Ruegeria pomeroyi DSS-3 grown in standard laboratory conditions. We used a shotgun approach consisting of trypsin digestion of the exoproteome, and identification of the resulting peptides by liquid chromatography coupled to tandem mass spectrometry. Three different proteins that have domains homologous to those observed in RTX toxins were uncovered and were semi-quantified as the most abundantly secreted proteins. One of these proteins clearly stands out from the catalogue, representing over half of the total exoproteome. We also listed many soluble proteins related to ABC and TRAP transporters implied in the uptake of nutrients. The Ruegeria pomeroyi DSS-3 case-study illustrates the power of the shotgun nano-LC-MS/MS strategy to decipher the exoproteome from marine bacteria and to contribute to environmental proteomics.     

Structure Elucidation and in Vitro Toxicity of New Azaspiracids Isolated from the Marine Dinoflagellate Azadinium poporum

Two strains of Azadinium poporum, one from the Korean West coast and the other from the North Sea, were mass cultured for isolation of new azaspiracids. Approximately 0.9 mg of pure AZA-36 (1) and 1.3 mg of pure AZA-37 (2) were isolated from the Korean (870 L) and North Sea (120 L) strains, respectively. The structures were determined to be 3-hydroxy-8-methyl-39-demethyl-azaspiracid-1 (1) and 3-hydroxy-7,8-dihydro-39-demethyl-azaspiracid-1 (2) by ¹H- and ¹³C-NMR. Using the Jurkat T lymphocyte cell toxicity assay, (1) and (2) were found to be 6- and 3-fold less toxic than AZA-1, respectively.