Marine sponge microbial association: Towards disclosing unique symbiotic interactions

Navigating spatio-temporal microbiome dynamics: Environmental factors and trace elements shape the symbiont community of an invasive marine species

The proliferation of marine invasive species is a mounting concern. While the role of microbial communities in invasive ascidian species is recognized, the role of seasonal shifts in microbiome composition remains largely unexplored. We sampled five individuals of the invasive ascidian Styela plicata quarterly from January 2020 to October 2021 in two harbours, examining gills, tunics, and surrounding water. By analysing Amplicon Sequence Variants (ASVs) and seawater trace elements, we found that compartment (seawater, tunic, or gills) was the primary differentiating factor, followed by harbour. Clear seasonal patterns were evident in seawater bacteria, less so in gills, and absent in tunics. We identified compartment-specific bacteria, as well as seasonal indicator ASVs and ASVs correlated with trace element concentrations. Among these bacteria, we found that Endozoicomonas, Hepatoplasma and Rhodobacteraceae species had reported functions which might be necessary for overcoming seasonality and trace element shifts. This study contributes to understanding microbiome dynamics in invasive holobiont systems, and the patterns found indicate a potential role in adaptation and invasiveness.

Comprehensive insights into the differences of fungal communities at taxonomic and functional levels in stony coral Acropora intermedia under a natural bleaching event

Previous studies have reported the correlations between bacterial communities and coral bleaching, but the knowledge of fungal roles in coral bleaching is still limited. In this study, the taxonomic and functional diversities of fungi in unbleached, partly bleached and bleached stony coral Acropora intermedia were investigated through the ITS-rRNA gene next-generation sequencing. An unexpected diversity of successfully classified fungi (a total of 167 fungal genera) was revealed in this study, and the partly bleached coral samples gained the highest fungal diversity, followed by bleached and unbleached coral samples. Among these fungi, 122 genera (nearly 73.2%) were rarely found in corals in previous studies, such as Calostoma and Morchella, which gave us a more comprehensive understanding of coral-associated fungi. Positively correlated fungal genera (Calostoma, Corticium, Derxomyces, Fusicolla, Penicillium and Vishniacozyma) and negative correlated fungal genera (Blastobotrys, Exophiala and Dacryopinax) with the coral bleaching were both detected. It was found that a series of fungal genera, dominant by Apiotrichum, a source of opportunistic infections, was significantly enriched; while another fungal group majoring in Fusicolla, a probiotic fungus, was distinctly depressed in the bleached coral. It was also noteworthy that the abundance of pathogenic fungi, including Fusarium, Didymella and Trichosporon showed a rising trend; while the saprotrophic fungi, including Tricladium, Botryotrichum and Scleropezicula demostrated a declining trend as the bleaching deteriorating. The rising of pathogenic fungi and the declining of saprotrophic fungi revealed the basic rules of fungal community transitions in the coral bleaching, but the mechanism of coral-associated fungal interactions still lacks further investigation. Overall, this is an investigation focused on the differences of fungal communities at taxonomic and functional levels in stony coral A. intermedia under different bleaching statuses, which provides a better comprehension of the correlations between fungal communities and the coral bleaching.

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.

Advances in Natural Products from the Marine-Sponge-Associated Microorganisms with Antimicrobial Activity in the Last Decade

Microorganisms are the dominating source of food and nutrition for sponges and play an important role in sponge structure, chemical defense, excretion and evolution. In recent years, plentiful secondary metabolites with novel structures and specific activities have been identified from sponge-associated microorganisms. Additionally, as the phenomenon of the drug resistance of pathogenic bacteria is becoming more and more common, it is urgent to discover new antimicrobial agents. In this paper, we reviewed 270 secondary metabolites with potential antimicrobial activity against a variety of pathogenic strains reported in the literature from 2012 to 2022. Among them, 68.5% were derived from fungi, 23.3% originated from actinomycetes, 3.7% were obtained from other bacteria and 4.4% were discovered using the co-culture method. The structures of these compounds include terpenoids (13%), polyketides (51.9%), alkaloids (17.4%), peptides (11.5%), glucosides (3.3%), etc. Significantly, there are 124 new compounds and 146 known compounds, 55 of which have antifungal activity in addition to antipathogenic bacteria. This review will provide a theoretical basis for the further development of antimicrobial drugs.

Unravelling the sponge microbiome as a promising source of biosurfactants

Microbial surfactants are particularly useful in bioremediation and heavy metal removal from soil and aquatic environments, amongst other highly valued uses in different economic and biomedical sectors. Marine sponge-associated bacteria are well-known producers of bioactive compounds with a wide array of potential applications. However, little progress has been made on investigating biosurfactants produced by these bacteria, especially when compared with other groups of biologically active molecules harnessed from the sponge microbiome. Using a thorough literature search in eight databases, the purpose of the review was to compile the current knowledge on biosurfactants from sponge-associated bacteria, with a focus on their relevant biotechnological applications. From the publications between the years 1995 and 2021, lipopeptides and glycolipids were the most identified chemical classes of biosurfactants. Firmicutes was the dominant phylum of biosurfactant-producing strains, followed by Actinobacteria and Proteobacteria. Bioremediation led as the most promising application field for the studied surface-active molecules in sponge-derived bacteria, despite the reports endorsed their use as antimicrobial and antibiofilm agents. Finally, we appoint some key strategies to instigate the research appetite on the isolation and characterization of novel biosurfactants from the poriferan microbiome.

Two New Alkaloids and a New Butenolide Derivative from the Beibu Gulf Sponge-Derived Fungus Penicillium sp. SCSIO 41413

Marine sponge-derived fungi have been proven to be a prolific source of bioactive natural products. Two new alkaloids, polonimides E (1) and D (2), and a new butenolide derivative, eutypoid F (11), were isolated from the Beibu Gulf sponge-derived fungus, Penicillium sp. SCSIO 41413, together with thirteen known compounds (3-10, 12-16). Their structures were determined by detailed NMR, MS spectroscopic analyses, and electronic circular dichroism (ECD) analyses. Butenolide derivatives 11 and 12 exhibited inhibitory effect against the enzyme PI3K with IC₅₀ values of 1.7 μM and 9.8 μM, respectively. The molecular docking was also performed to understand the inhibitory activity, while 11 and 12 showed obvious protein/ligand-binding effects to the PI3K protein. Moreover, 4 and 15 displayed obvious inhibitory activity against LPS-induced NF-κB activation in RAW264.7 cells at 10 µM.

Microbiome composition of the marine sponge Cliona varians at the Neotropical Southern Caribbean Sea displays a predominant core of Rhizobiales and Nitrosopumilaceae

AIMS

This work aims to characterize the microbial diversity of the encrusting sponge Cliona varians, a pore-forming and coral reef bioeroding marine sponge of emerging spread related to ocean acidification.

METHODS AND RESULTS

We analyzed the microbiome composition by 16S V4 amplicon next-generation sequencing in a community of the bioeroding coral-reef encrusting/excavating marine sponge Cliona varians thriving at the Southern Caribbean Sea. 87.21% and 6.76% of the sequences retrieved were assigned to the domain Bacteria and Archaea. The most predominant operational taxonomic units were classified as members of the order Rhizobiales and family Nitrosopumilaceae, representing members of not yet characterized genera. Features found strictly conserved in the strain/genomic representatives reported in those microbial taxa are nitrogen fixation and transformation.

CONCLUSION

Our results suggest, in accordance with recent results, that these microbiome members and associated functions could be contributing to the biological fitness of the sponge to be able to colonize and bioerode in environments with low access and scarce availability of nitrogen source.

SIGNIFICANCE AND IMPACT OF STUDY

Coral reefs bioresources such as sponge holobionts are intriguing and complex ecosystems units. This study contributes to the knowledge of how C. varians microbiota is composed or shaped, which is crucial to understand its ecological functions.

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.

Reductive deiodination of 2,4,6-triiodophenol by Vallitalea sp. strain TIP-1 isolated from the marine sponge

An anaerobic microbial consortium capable of reductively dehalogenating 2,4,6-triiodophenol (2,4,6-TIP) was enriched from the marine sponge Hymeniacidon sinapium. The enrichment reductively deiodinated 100 μM of 2,4,6-TIP to 4-iodophenol (4-IP) and 2-iodophenol (2-IP) in the presence of sterile sponge tissue as the sole carbon source and electron donor. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequence analysis revealed that bacteria closely related with Vallitalea guaymasensis and Oceanirhabdus sediminicola, both of which are members of the order Clostridiales, were predominant in the enrichment. When glucose was added to the enrichment as alternative carbon source, one of these bacteria grew predominantly, which was subsequently isolated as a pure culture. The strain, designated as TIP-1, showed 99.7% 16S rRNA gene sequence similarity with V. guaymasensis. In the presence of glucose, strain TIP-1 reductively deiodinated 2,4,6-TIP to 2-IP and 4-IP at a molar ratio of 3:1, during which 2,4-diiodophenol (2,4-DIP) and 2,6-diiodophenol (2,6-DIP) were observed as deiodinated intermediates. Glucose was required for 2,4,6-TIP deiodination, but 2,4,6-TIP was not essential for growth of strain TIP-1. The strain also deiodinated 2,4-DIP to 2-IP and 4-IP at a molar ratio of 1:1, and 2,6-DIP to 2-IP, but further deiodination of the monoiodophenols was not observed. These results suggest that strain TIP-1 removed both ortho- and para-substituted iodines equally. Such deiodinating bacteria could be applied to the mineralization or dehalogenation of triiodobenzene derivatives, which are widely used as X-ray contrast media.

Cytotoxic Polyketide Metabolites from a Marine Mesophotic Zone Chalinidae Sponge-Associated Fungus Pleosporales sp. NBUF144

Two new polyketide natural products, globosuxanthone F (1), and 2′-hydroxy bisdechlorogeodin (2), were isolated from the fungus Pleosporales sp. NBUF144, which was derived from a 62 m deep Chalinidae family sponge together with four known metabolites, 3,4-dihydroglobosuxanthone A (3), 8-hydroxy-3-methylxanthone-1-carboxylate (4), crosphaeropsone C (5), and 4-megastigmen-3,9-dione (6). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR and high-resolution electrospray ionization mass spectra (HRESIMS) data. The absolute configuration of 1 was further established by single-crystal X-ray diffraction studies. Compounds 1–5 were evaluated for cytotoxicity towards CCRF-CEM human acute lymphatic leukemia cells, and it was found that 1 had an IC₅₀ value of 0.46 µM.

Cultivable yeasts associated with marine sponges in the Gulf of Thailand, South China Sea

Marine sponges harbor numerous microorganisms, among which sponge-associated yeasts are the least explored. To gain greater knowledge of sponge-associated yeasts, an investigation was therefore performed on marine sponges in Sattahip Bay, Gulf of Thailand, South China Sea. Seventy-one (71) marine sponge samples were collected at sites near Samae-san, Mu, and Khram islands, and were subsequently identified as 17 sponge species in 14 genera. Eighty-seven (87) yeast strains were isolated from 42 samples. The identification of yeasts by similarity analysis of the D1/D2 domain sequences of the large subunit rRNA gene revealed that 64% of the yeast strains obtained belonged to the phylum Basidiomycota, while the remaining strains belonged to the phylum Ascomycota. The strains that belonged to Ascomycota comprised 11 known yeast species in five genera (Candida, Kodamaea, Magnusiomyces, Meyerozyma, and Pichia). The strains belonging to the phylum Basidiomycota comprised 14 known yeast species in eight genera (Cutaneotrichosporon, Cystobasidium, Naganishia, Papiliotrema, Rhodosporidiobolus, Rhodotorula, Trichosporon, and Vishniacozyma). In addition, three strains represented a potential novel species closest to Cys. slooffiae; one strain represented a potential novel species closest to R. toruloides; and one strain represented a potential novel species closest to V. foliicola. The species with the highest occurrence was Rhodotorula mucilaginosa. No marked difference was found in the principal coordinates analysis of the ordinations of yeast communities from the three sampling sites. The estimation using EstimateS software showed that the expected species richness was higher than the observed species richness. As the marine sponge-yeast association remains unclear, more systematic investigations should be carried out.

Bacterial diversity associated with a newly described bioeroding sponge, Cliona thomasi, from the coral reefs on the West Coast of India

The bacterial diversity associated with eroding sponges belonging to the Cliona viridis species complex is scarcely known. Cliona thomasi described from the West Coast of India is a new introduction to the viridis species complex. In this study, we determined the bacterial diversity associated with C. thomasi using next-generation sequencing. The results revealed the dominance of Proteobacteria followed by Cyanobacteria, Actinobacteria and Firmicutes. Among Proteobacteria, the Alphaproteobacteria were found to be the most dominant class. Furthermore, at the genus level, Rhodothalassium were highly abundant followed by Endozoicomonas in sponge samples. The beta-diversity and species richness measures showed remarkably lower diversity in Cliona thomasi than the ambient environment. The determined lower bacterial diversity in C. thomasi than the environmental samples, thus, categorized it as a low microbial abundance (LMA). Functional annotation of the C. thomasi-associated bacterial community indicates their possible role in photo-autotrophy, aerobic nitrification, coupling of sulphate reduction and sulphide oxidization. The present study unveils the bacterial diversity in bioeroding C. thomasi, which is a crucial step to determine the functions of the sponge holobiont in coral reef ecosystem.

Antibacterial scalarane from Doriprismatica stellata nudibranchs (Gastropoda, Nudibranchia), egg ribbons, and their dietary sponge Spongia cf. agaricina (Demospongiae, Dictyoceratida)

Investigations on the biochemical relationship between Doriprismatica stellata (Chromodorididae, Doridoidea) nudibranchs, their egg ribbons, and the associated dietary sponge Spongia cf. agaricina (Demospongiae, Porifera) led to the isolation of the structurally new scalarane-type sesterterpene 12-deacetoxy-4-demethyl-11,24-diacetoxy-3,4-methylenedeoxoscalarin, with an unprecedented position of the cyclopropane ring annelated to the ring A. Unlike other scalaranes, which are most often functionalized at C-12 of ring C, it bears two acetoxy groups at C-11 and C-24 instead. The compound was present in all three samples, supporting the dietary relationship between chromodorid nudibranchs of the genus Doriprismatica and scalarane-containing dictyoceratid sponges of the Spongiidae family. The results also indicate that D. stellata passes the scalarane metabolite on to its egg ribbons, most likely for protective purposes. The scalarane showed antibacterial activity against the Gram-positive bacteria Arthrobacter crystallopoietes (DSM 20117) and Bacillus megaterium (DSM 32).

Diversity and antimicrobial potential of Actinobacteria isolated from diverse marine sponges along the Beibu Gulf of the South China Sea

Marine sponge-associated microorganisms have proven to be a very promising source of biologically active and pharmaceutically important natural products. In this study, we investigated the diversity and antibacterial potential of bacteria from 49 sponge species isolated from the Beibu Gulf, South China Sea, belonging to 16 genera and several unidentified taxa. Using a variety of selective media, 363 strains with different morphologies were identified to six bacterial taxa, including Proteobacteria (α-subgroup 85 and γ-subgroup 59), Actinobacteria (123), Firmicutes (90), Bacteroidetes (5) and Brevundimonas (1). Media ISP2 and R2A were the most effective for isolating Actinobacteria. One hundred and twenty-three actinobacterial strains clustered into 21 genera identified by 16S rDNA gene sequencing, most of which were from the genus Microbacterium, followed by Pseudonocardia, Streptomyces, Kocuria, Aeromicrobium, Brachybacterium and Nocardiopsis, constituted 82% of total actinobacterial isolates. By using the minimal medium, 92 actinobacterial isolates showed antimicrobial activities, and 51 strains displayed moderate to strong antimicrobial activity that inhibited the growth of more than half of the bacteria tested in this study. Functional genes related to secondary metabolites were screened, revealing that 10% (12/123) of actinobacterial isolates contained PKS-KS genes, 18% (22/123) harbored NRPS-A genes and 6% (7/123) had hybrid PKS-NRPS gene clusters. The sponges Haliclona sp., Callyspongia sp. and Desmacella sp., belonging to class Demonspongiae, and Leucaltis sp. from the class Calcarea, were dominant hosts, harboring the most diverse actinobacterial genera with stronger antimicrobial activities and more diverse PKS/NRPS genes.

Two new aromatic polyketides from a sponge-derived Fusarium

In our natural product screening program from marine fungi, two new aromatic polyketides karimunones A (1) and B (2) and five known compounds (3–7) were isolated from sponge-associated Fusarium sp. KJMT.FP.4.3 which was collected from an Indonesian sponge Xestospongia sp. The structures of these compounds were determined by the analysis of NMR and MS spectroscopic data. The NMR assignment of 1 was assisted by DFT-based theoretical chemical shift calculation. Compound 2 showed antibacterial activity against multidrug resistant Salmonella enterica ser. Typhi with a MIC of 125 µg/mL while 1 was not active.

Impact of the Cultivation Technique on the Production of Secondary Metabolites by Chrysosporium lobatum TM-237-S5, Isolated from the Sponge Acanthella cavernosa

The fungi Chrysosporium lobatum TM-237-S5 was isolated from the sponge Acanthella cavernosa, collected from the mesophotic coral ecosystem of the Red Sea. The strain was cultivated on a potato dextrose agar (PDA) medium, coupling solid-state fermentation and solid-state extraction (SSF/SSE) with a neutral macroreticular polymeric adsorbent XAD Amberlite resin (AMBERLITE XAD1600N). The SSF/SSE lead to high chemodiversity and productivity compared to classical submerged cultivation. Ten phenalenone related compounds were isolated and fully characterized by one-dimensional and two-dimensional NMR and HRMS. Among them, four were found to be new compounds corresponding to isoconiolactone, (-)-peniciphenalenin F, (+)-8-hydroxyscleroderodin, and (+)-8-hydroxysclerodin. It is concluded that SSF/SSE is a powerful strategy, opening a new era for the exploitation of microbial secondary metabolites.

Comparative Genomics of Marine Sponge-Derived Streptomyces spp. Isolates SM17 and SM18 With Their Closest Terrestrial Relatives Provides Novel Insights Into Environmental Niche Adaptations and Secondary Metabolite Biosynthesis Potential

The emergence of antibiotic resistant microorganisms has led to an increased need for the discovery and development of novel antimicrobial compounds. Frequent rediscovery of the same natural products (NPs) continues to decrease the likelihood of the discovery of new compounds from soil bacteria. Thus, efforts have shifted toward investigating microorganisms and their secondary metabolite biosynthesis potential, from diverse niche environments, such as those isolated from marine sponges. Here we investigated at the genomic level two Streptomyces spp. strains, namely SM17 and SM18, isolated from the marine sponge Haliclona simulans, with previously reported antimicrobial activity against clinically relevant pathogens; using single molecule real-time (SMRT) sequencing. We performed a series of comparative genomic analyses on SM17 and SM18 with their closest terrestrial relatives, namely S. albus J1074 and S. pratensis ATCC 33331 respectively; in an effort to provide further insights into potential environmental niche adaptations (ENAs) of marine sponge-associated Streptomyces, and on how these adaptations might be linked to their secondary metabolite biosynthesis potential. Prediction of secondary metabolite biosynthetic gene clusters (smBGCs) indicated that, even though the marine isolates are closely related to their terrestrial counterparts at a genomic level; they potentially produce different compounds. SM17 and SM18 displayed a better ability to grow in high salinity medium when compared to their terrestrial counterparts, and further analysis of their genomes indicated that they possess a pool of 29 potential ENA genes that are absent in S. albus J1074 and S. pratensis ATCC 33331. This ENA gene pool included functional categories of genes that are likely to be related to niche adaptations and which could be grouped based on potential biological functions such as osmotic stress, defense; transcriptional regulation; symbiotic interactions; antimicrobial compound production and resistance; ABC transporters; together with horizontal gene transfer and defense-related features.

Marine sponges of the genus Stelletta as promising drug sources: chemical and biological aspects

Marine sponges of the genus Stelletta are well known as rich sources of diverse and complex biologically relevant natural products, including alkaloids, terpenoids, peptides, lipids, and steroids. Some of these metabolites, with novel structures and promising biological activities, have attracted a lot of attention from chemists seeking to perform their total synthesis in parallel to intensive biological studies towards new drug leads. In this review, we summarized the distribution of the chemically investigated Stelletta sponges, the isolation, synthesis and biological activities of their secondary metabolites, covering the literature from 1982 to early 2018.