Sponge-associated Microorganisms Research Articles

Exploring the microbial community and biotechnological potential of the sponge Xestospongia sp. from an anchialine cave in the Yucatán Peninsula

Sponge-associated microorganisms are key influencers of nutrient biogeochemistry and important sources of bioactive natural products. This study provides the first insights into the taxonomic diversity of the microbial community associated with the sponge Xestospongia sp. from an anchialine cave in the coastal area of the underground river of the Yucatán Peninsula in Xcalak, Quintana Roo, Mexico, and the potential antimicrobial activity of its cultivable bacteria. High abundances of Sulfurospirillum and Desulfovibrio were detected with 16S rRNA amplicons, suggesting that the microbial community of Xestospongia sp. plays an important role in the geochemical sulfur cycle. Analysis with crude extracts of Nocardiopsis dasonvillei NCA-454 revealed antimicrobial activity against methicillin-sensitive Staphylococcus aureus ATCC 25913 (MSSA) and methicillin-​resistant ​S. aureus ATCC 43300 (MRSA). Studies of the microbiomes of sponges from the anchialine cave system in the Yucatán Peninsula can help elucidate the biogeochemical cycles of these poorly studied environments. Moreover, the microorganisms of these microbial communities represent an untapped source of secondary metabolites with biotechnological potential.

Genomic insights into symbiosis and host adaptation of sponge-associated novel bacterium, Rossellomorea orangium sp. nov.

Sponge-associated microorganisms play vital roles in marine sponge ecology. This study presents a genomic investigation of Rossellomorea sp. MCCB 382, isolated from Stelletta sp., reveals insights into its adaptations and symbiotic roles. Phylogenomic study and Overall Genomic Relatedness Index (OGRI) classify MCCB 382 as a novel species, Rossellomorea orangium sp. nov. The genome encodes numerous carbohydrate metabolism enzymes (CAZymes), likely aiding nutrient cycling in the sponge host. Unique eukaryotic-like protein domains hint at potential mechanisms of symbiosis. Defence mechanisms include CRISPR, restriction-modification systems, DNA phosphorothioation, toxin-antitoxin systems, and heavy metal and multidrug resistance genes, indicating adaptation to challenging marine environments. Unlike obligate mutualists, MCCB 382 shows no genome reduction. Furthermore, the presence of mobile genetic elements, horizontal gene transfer, and prophages suggest genetic versatility, implying flexible metabolic potential and capacity for rapid adaptation and symbiosis shifts. MCCB 382 possesses six biosynthetic gene clusters for secondary metabolites, including both type II and III polyketide synthases (PKS), terpenes, (NRPS), NRPS-independent-siderophore, and lassopeptide. Further genome mining using BiGScape revealed four distinct gene cluster families, T2PKS, NRPS-independent-siderophore, lasso peptide, and terpene, presenting opportunities for novel compound elucidation. Our study reveals a symbiotic lifestyle of MCCB 382 with the host sponge, highlighting symbiont factors that aid in establishing and sustaining this relationship. This is the pioneering genomic characterization of a novel Rossellomorea sp. within the sponge Stelletta sp. holobiont.

Genome-resolved metagenomic analysis of Great Amazon Reef System sponge-associated Latescibacterota bacteria and their potential contributions to the host sponge and reef

The Great Amazon Reef System (GARS) is an extensive biogenic reef influenced by a plume layer of sediments. This creates an extreme environment where light is reduced, thus affecting physicochemical properties as well as living organisms such as sponges and their microbiomes. The sponge’s microbiome has numerous ecological roles, like participation in biogeochemical cycles and host nutrition, helping the sponge thrive and contributing to the ecosystem. Also, sponges and sponge-associated microorganisms are rich sources of bioactive compounds, and their products are applied in different areas, including textile, pharmaceutical, and food industries. In this context, metagenome-assembled genomes (MAG), obtained from GARS sponges microbiota, were analyzed to predict their ecological function and were prospected for biotechnological features. Thus, in this work, tissues of GARS sponges were collected, their metagenomes were sequenced and assembled, and 1,054 MAGs were recovered. Ten of those MAGs were selected based on their taxonomic classification in the candidate phylum Latescibacterota and this group’s abundance in GARS sponges. The workflow consisted of MAG’s quality definition, taxonomic classification, metabolic reconstruction, and search for bioactive compounds. Metabolic reconstruction from medium to high-quality MAGs revealed genes related to degradation and synthesis pathways, indicating functions that may be performed by GARS sponge-associated Latescibacterota. Heterotrophy, a recurring attribute in Latescibacterota that might be crucial for GARS sponge holobiont nutrition, was verified by the presence of genes related to respiration and fermentation. Also, the analyzed bacteria may contribute to the host’s survival in multiple ways, including host protection via defense systems; aid in nutrient consumption by breaking complex substrates and producing essential nutrients like vitamins and certain amino acids; and detoxification of mercury, arsenic, ammonia, and hydrogen sulfide. Additionally, genes linked to persistent organic pollutant degradation, including glyphosate, and biogeochemical cycles reactions, such as ammonification, sulfate reduction, thiosulfate disproportionation, phosphorus remineralization, and complex organic matter degradation, were identified, suggesting the participation of these Latescibacterota in bioremediation and nutrient cycling. Finally, the investigated MAGs contain genes for numerous bioactive compounds, including industrial enzymes, secondary metabolites, and biologically active peptides, which may have biotechnological value.

The natural products discovered in marine sponge-associated microorganisms: structures, activities, and mining strategy

It is well known that microorganisms are abundant in sponges, which make up 50%-60% of the host biomass. Moreover, mounting evidence suggests that bacteria, fungi, and cyanobacteria, all associated with sponges, are the true creators of the bioactive compounds identified from sponges. The discovery of 774 structurally active compounds from 1998 to 2017 presents a good overview of natural product resources in sponge-associated microorganisms. During the last 5 years, many new molecules, including peptides, polyketides, alkaloids, and terpenes, have been identified from sponge-associated microorganisms through various mining strategies, exhibiting a wide range of biological activities, such as anti-microbial, anti-cancer, enzyme inhibition, and antioxidant properties. In this paper, 140 compounds produced by sponge-associated microorganisms from 2017 to 2022 are systematically discussed in terms of their structures, biological activities, and strain sources, as well as the mining strategies, which not only further updates the natural product library of sponge-associated microorganisms but also provides a new guideline for exploring the “dark matter” in sponges.

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.

Time for a Change! A Spotlight on Many Neglected Facets of Sponge Microbial Biotechnology.

The sponge-microorganism partnership is one of the most successful symbiotic associations exploited from a biotechnological perspective. During the last thirty years, sponge-associated bacteria have been increasingly harnessed for bioactive molecules, notably antimicrobials and cytotoxic compounds. Unfortunately, there are gaps in sponge microbial biotechnology, with a multitude of applications being understudied or ignored. In this context, the current perspective aims to shed light on these underrated facets of sponge microbial biotechnology with a balance of existent reports and proposals for further research in the field. Our overview has showcased that the members of the sponge microbiome produce biomolecules whose usage can be valuable for several economically- relevant and demanding sectors. Outside the exhaustive search for antimicrobial secondary metabolites, sponge-associated microorganisms are gifted producers of antibiofilm, antivirulence and chronic diseases-attenuating substances highly envisaged by the pharmaceutical industry. Despite still at an infant stage of research, anti-ageing enzymes and pigments of special interest for the cosmetic and cosmeceutical sectors have also been reported from the sponge microbial symbionts. In a world urging for sustainability, sponge-associated microorganisms have been proven as fruitful resources for bioremediation, including recovery of heavy-metal contaminated areas, bioleaching processes, and as bioindicators of environmental pollution. In conclusion, we propose alternatives to better assess these neglected biotechnological applications of the sponge microbiome in the hope of sparking the interest of the scientific community toward their deserved exploitation.

Application of metabolomics on marine sponges and sponge-associated microorganisms: A review

Metabolomic study and in silico approach of DLBS1442 as progesterone receptor agonistNatalia Windari Rahardjo, Emanuel Dani Ramdani, Raymond Rubianto Tjandrawinata, Yanti

Recent Advances of Marine Sponge-Associated Microorganisms as a Source of Commercially Viable Natural Products.

Many industrially significant compounds have been derived from natural products in the environment. Research efforts so far have contributed to the discovery of beneficial natural products that have improved the quality of life on Earth. As one of the sources of natural products, marine sponges have been progressively recognised as microbial hotspots with reports of the sponges harbouring diverse microbial assemblages, genetic material, and metabolites with multiple industrial applications. Therefore, this paper aims at reviewing the recent literature (primarily published between 2016 and 2022) on the types and functions of natural products synthesised by sponge-associated microorganisms, thereby helping to bridge the gap between research and industrial applications. The metabolites that have been derived from sponge-associated microorganisms, mostly bacteria, fungi, and algae, have shown application prospects especially in medicine, cosmeceutical, environmental protection, and manufacturing industries. Sponge bacteria-derived natural products with medical properties harboured anticancer, antibacterial, antifungal, and antiviral functions. Efforts in re-identifying the origin of known and future sponge-sourced natural products would further clarify the roles and significance of microbes within marine sponges.

Variability in Host Specificity and Functional Potential of Antarctic Sponge-Associated Bacterial Communities.

Sponge-associated microorganisms are essential for sponge survival. They play an important role in recycling nutrients and, therefore, in the maintenance of the ecosystem. These microorganisms are diverse, species-specific, and different from those in the surrounding seawater. Bacterial sponge symbionts have been extensively studied in the tropics; however, little is known about these microorganisms in sponges from high-latitude environments. Sponges can cover up to 80% of the benthos in Antarctica and are crucial architects for the marine food web. In this study, we present analyses of the bacterial symbionts of three sponges: Haliclona (Rhizoniera) sp., Hymeniacidon torquata, and Isodictya kerguelenensis from the Western Antarctic Peninsula (WAP) with the aim to determine variations on the specificity of the bacteria–sponge interactions and potential signatures on their predicted functional profiles. We use high-throughput 16S rRNA gene sequencing of 30 sponge individuals inhabiting South Bay (Palmer Archipelago, WAP) to describe their microbiome taxonomy and diversity and predict potential functional profiles based on this marker gene. Our work shows similar bacterial community composition profiles among the same sponge species, although the symbiotic relationship is not equally conserved among the three Antarctic sponges. The number of species-specific core operational taxonomic units (OTUs) of these Antarctic sponges was low, with important differences between the total abundance accounted for these OTUs. Only eight OTUs were shared between the three sponge species. Analyses of the functional potential revealed that despite the high host–symbiont specificity, the inferred functions are conserved among these microbiomes, although with differences in the abundance of specific functions. H. torquata showed the highest level of intra-specificity and a higher potential of pathways related to energy metabolism, metabolisms of terpenoids and polyketides, and biosynthesis of other secondary metabolites. Overall, this work shows variations in the specificity of the sponge-associated bacterial communities, differences in how hosts and symbionts establish their relations, and in their potential functional capabilities.

Genomic and in silico protein structural analyses provide insights into marine polysaccharide-degrading enzymes in the sponge-derived Pseudoalteromonas sp. PA2MD11

Active heterotrophic metabolism is a critical metabolic role performed by sponge-associated microorganisms, but little is known about their capacity to metabolize marine polysaccharides (MPs). Here, we investigated the genome of the sponge-derived Pseudoalteromonas sp. strain PA2MD11 focusing on its macroalgal carbohydrate-degrading potential. Carbohydrate-active enzymes (CAZymes) for the depolymerization of agar and alginate were found in PA2MD11's genome, including glycoside hydrolases (GHs) and polysaccharide lyases (PLs) belonging to families GH16, GH50 and GH117, and PL6 and PL17, respectively. A gene potentially encoding a sulfatase was also identified, which may play a role in the strain's ability to consume carrageenans. The complete metabolism of agar and alginate by PA2MD11 could also be predicted and was consistent with the results obtained in physiological assays. The polysaccharide utilization locus (PUL) potentially involved in the metabolism of agarose contained mobile genetic elements from other marine Gammaproteobacteria and its unusual larger size might be due to gene duplication events. Homology modelling and structural protein analyses of the agarases, alginate lyases and sulfatase depicted clear conservation of catalytic machinery and protein folding together with suitable industrially-relevant features. Pseudoalteromonas sp. PA2MD11 is therefore a source of potential MP-degrading biocatalysts for biorefinery applications and in the preparation of pharmacologically-active oligosaccharides.

Multi-omics Comparative Analysis of Streptomyces Mutants Obtained by Iterative Atmosphere and Room-Temperature Plasma Mutagenesis.

Sponges, the most primitive multicellular animals, contain a large number of unique microbial communities. Sponge-associated microorganisms, particularly actinomyces, have the potential to produce diverse active natural products. However, a large number of silent secondary metabolic gene clusters have failed to be revived under laboratory culture conditions. In this study, iterative atmospheric room-temperature plasma. (ARTP) mutagenesis coupled with multi-omics conjoint analysis was adopted to activate the inactive wild Streptomyces strain. The desirable exposure time employed in this study was 75 s to obtain the appropriate lethality rate (94%) and mutation positive rate (40.94%). After three iterations of ARTP mutagenesis, the proportion of mutants exhibiting antibacterial activities significantly increased by 75%. Transcriptome analysis further demonstrated that the differential gene expression levels of encoding type I lasso peptide aborycin had a significant upward trend in active mutants compared with wild-type strains, which was confirmed by LC-MS results with a relative molecular mass of 1082.43 ([M + 2H]2+ at m/z = 2164.86). Moreover, metabolome comparative analysis of the mutant and wild-type strains showed that four spectra or mass peaks presented obvious differences in terms of the total ion count or extracting ion current profiles with each peak corresponding to a specific compound exhibiting moderate antibacterial activity against Gram-positive indicators. Taken together, our data suggest that the ARTP treatment method coupled with multi-omics profiling analysis could be used to estimate the valid active molecules of metabolites from microbial crudes without requiring a time-consuming isolation process.

Characterization of Prodiginine Pathway in Marine Sponge-Associated Pseudoalteromonas sp. PPB1 in Hilo, Hawai‘i

Interest in bioactive pigments stems from their ecological role in adaptation, as well as their applications in various consumer products. The production of these bioactive pigments can be from a variety of biological sources, including simple microorganisms that may or may not be associated with a host. This study is particularly interested in the marine sponges, which have been known to harbor microorganisms that produce secondary metabolites like bioactive pigments. In this study, marine sponge tissue samples were collected from Puhi Bay off the Eastern shore of Hilo, Hawai‘i and subsequently were identified as Petrosia sp. with red pigmentation. Using surface sterilization and aseptic plating of sponge tissue samples, sponge-associated microorganisms were isolated. One isolate (PPB1) produced a colony with red pigmentation like that of Petrosia sp., suggesting an integral relationship between this particular isolate and the sponge of interest. 16S characterization and sequencing of PPB1 revealed that it belonged to the Pseudoalteromonas genus. Using various biological assays, both antimicrobial and antioxidant bioactivity was shown in Pseudoalteromonas sp. PPB1 crude extract. To further investigate the genetics of pigment production, a draft genome of PPB1 was sequenced, assembled, and annotated. This revealed a prodiginine biosynthetic pathway and the first cited-incidence of a prodiginine-producing Pseudoalteromonas species isolated from a marine sponge host. Further understanding into the bioactivity and biosynthesis of secondary metabolites like pigmented prodiginine may uncover the complex ecological interactions between host sponge and microorganism.

Chloroflexi Dominate the Deep-Sea Golf Ball Sponges Craniella zetlandica and Craniella infrequens Throughout Different Life Stages

Deep-sea sponge grounds are underexplored ecosystems that provide numerous goods and services to the functioning of the deep-sea. This study assessed the prokaryotic diversity in embryos, juveniles and adults of Craniella zetlandica and Craniella infrequens, common and abundant representatives of deep-sea sponge grounds in the North Atlantic. Our results reveal that symbiont transmission in Craniella sponges likely occurs vertically, as highly similar microbial consortia have been identified in adults, embryos, and juvenile stages. Moreover, transmission electron microscopy revealed high abundances of sponge-associated microorganisms, among which Chloroflexi (SAR 202) were identified as common representatives by amplicon sequencing and fluorescent in-situ hybridization (FISH). Equal diversity metrices, a similar overall prokaryotic community composition and a distinct dominance of the phylum Chloroflexi within all life stages are the key findings of our analyses. Information such as presented here provide understanding on the recruitment of deep-sea sponge holobionts which is needed to develop integrated management tools of such vulnerable marine ecosystems.

Expression and characterization of a new serine protease inhibitory protein in Escherichia coli

Introduction: Proteases are enzymes that catalyze the hydrolysis of peptide bonds and play an important role in almost all biological processes. However, excessive protein proteolysis can be implicated in several diseases, such as cancer, as well as cardiovascular, inflammatory, neurodegenerative, bacterial, viral and parasitic diseases. In these cases, protease inhibitors can be used as one of versatile tools for regulating proteolytic activity of target proteases as well as therapeutic applications. In this study, we expressed and characterized a new serine protease inhibitory protein (PI-QT) from the metagenome of sponge-associated microorganisms in Escherichia coli.
 Methods: The gene PI-QT encoding for a new serine protease inhibitory protein was expressed in E. coli BL21(DE3). In addition, the expressed protein was purified and characterized.
 Results: Optimization of expression of the recombinant protein PI-QT in E. coli showed that suitable conditions for expression of the protein were pre-induction cell density (OD600) of 0.6 - 0.7, IPTG concentration of 1 mM and temperature of 25oC. The protease inhibitory protein was also purified and identified by mass spectrometry LC-MS/MS. The recombinant protein showed inhibitory activity against trypsin anda-chymotrypsin with activity values of 97526 U/mg and 41714 U/mg, respectively. Maximum activity of the protease inhibitory protein was obtained at pH 7 and temperature 20-35oC. The inhibitor was stable over pH 4-9 and up to temperature 50oC. Addition of Zn2+, Mg2+ and Ca2+ enhanced inhibitory activity, whereas other metal ions, surfactants and oxidants reduced inhibitory activity of the protease inhibitor.
 Conclusion: The recombinant protein PI-QT is a potential protease inhibitor for therapeutic applications.

Expression of a novel gene encoding protease inhibitor from metagenome of sponge in Vietnam

Marine sponge is known as a “gold mine” of natural products from marine environment. Many novel bioactive compounds have been isolated from marine sponges and sponge-associated microorganisms such as antibiotics, anti-cancer compounds, protease inhibitors, etc. In this study, we selected a gene encoding protease inhibitor from metagenome of a sponge collected in Da Nang to express in Escherichia coli BL21(DE3). The gene PI-DN9 encoding protease inhibitor (1.3 kb) was cut off cloning vector pUC57/PI-DN9 containing gene PI-DN9 and inserted into expression vector pET32a(+), the recombinant vector pET32a(+)/PI-DN9 then was transformed and expressed in the E. coli strain BL21(DE3). Results showed that recombinant protein (50 kDa) was expressed successfully at 25°C, 1 mM of IPTG in 5 hours. The recombinant protein was purified using Ni-NTA affinity chromatography column. Western blot assay and bioactive assay showed good activity of the purified protein.

The bioactivity of bacterium and fungi living associate with the sponge Reniera sp. against multidrug-resistant Staphylococcus aureus and Escherichia coli

Abstract. Trianto A, Nirwani, Susanti O, Maesaroh D, Radjasa OK. 2019. The bioactivity of bacterium and fungi living associate with the sponge Reniera sp. against multidrug-resistant Staphylococcus aureus and Escherichia coli. Biodiversitas 20: 2302-2307. The study aimed to isolate and identify the sponge-associated microorganisms producing the antibacterial substances. The sponge Reniera sp. was collected by hand during skin diving in Karimunjawa Islands, Indonesia. The microbial symbionts were isolated with the dilution method and screened with the overlay method against the MDR S. aureus and E. coli. The bacterium was cultured in Zobell medium, while the fungi were cultured in malt extract broth (MEB) medium. The isolates were identified based on the molecular method. A total of 46 bacteria and 43 fungi were isolated, which 7 bacteria and 20 fungi exhibited antibacterial activity against the MDR E. coli and S. aureus strains. The molecular identification revealed that the active isolates close to Pseudoalteromonas maricaloris (99%), Aspergillus nomius (96%), Eurotium rubrum (99%), and Penicillium sp. (100%). Fractionation of K.J.16.U extract gave a fraction that active to the S. aureus and E. coli strains at concentration 150 and 15 µg disk-1. The fraction K.J.16.U.1.4.4 exhibited stronger activity than that exhibited by chloramphenicol at 150 µg disk-1. The sponge Reniera sp. collected from Karimunjawa Islands comprise bacterial and fungal isolates produced antibacterial compounds that inhibited the growth the MDR E. coli and S. aureus strains.

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.

Screening genes encoding protein protease inhibitor from metagenome of sponge-associated microorganisms in Quang Tri sea, Vietnam

Using metagenomics-based method to isolate new compounds from the marine environment are getting more and more attention in recent years. Based on metagenome library, bioinformatics methods is a powerful tool for screening genes with new biological activities from uncultured microorganisms and become a breakthrough in research and application of biotechnology. In this study we selected and used the samples DNA QT2 which had high DNA content and purity from a total of 6 DNA samples of sponge-associated microorganisms collected in Quang Tri sea (Vietnam) for metagenomic sequencing (DNA concentration is 202.5 ng, A260/ A280 value is 1.80). 16S rRNA metagenomic sequencing data of QT2 produced 44,117,722 reads, which were assembled into 120,236 contigs. ORF prediction using Prodigal produced 386,416 ORFs. Functional annotation was conducted based on 7 different databases (NR, COG, CAZy, Swissprot, GO, KEGG, Pfam), and there are 266,553 genes were annotated using Swiss-Prot. In addition, based on the obtained metagenomic data, 50 complete genes encoding protease inhibitor proteins were revealed and among them, 28 genes encoding protein (> 50%) belonged to the serine protease inhibitor family, and 22 genes genes encoding belonged to the Inter-alpha-trypsin inhibitor group. NCBI BLAST screening results that these proteins had higher 50% identity to protease inhibitors.

Contraction Dynamics and Respiration of Small Single-Osculum Explants of the Demosponge Halichondria panicea

: Sponges pump large amounts of seawater through their water canal system, providing both food and oxygen to the sponge body. Sponge pumping activity may show considerable variation as a consequence of contractile behavior, which includes contraction and expansion of the exhalant opening (osculum) in regular or irregular time intervals. The present study unravels short- and long-term effects of contraction-expansion events on the respiration rate of small single-osculum explants of the demosponge Halichondria panicea. Based on simultaneous video-microscopic time-lapse recordings of osculum cross-sectional area (OSA) and projected area (A), combined with respiration rate measurements, we further evaluate the role of pumping activity for oxygen uptake in the explants. Pumping dynamics were expressed by cyclic contraction-expansion events of the OSA and A, including osculum closure with a mean duration of 37.5 ± CI95% 13.7 min. The respiration rate of sponge explants remained relatively constant at 0.046 ± CI95% 0.014 µmol O2 h-1 (i.e., 7.41 µmol O2 h-1 g-1 DWsponge) during contraction-expansion cycles, but with a marginal decrease of 9.6 % during osculum closure. Periods of pumping cessation during osculum closure likely caused reduced oxygen levels in the sponge body, increasing the oxygen gradient between the environment and the sponge interior, allowing enhanced diffusion of oxygen across the explant surface. This is a key mechanism for balancing respiratory demands during sponge contractions. While contractile behavior is only marginally associated with decreased respiratory demands in small single-osculum H. panicea explants, it may control the degree of internal oxygen depletion and thereby ensure maintenance of sponge-associated microorganisms during non-pumping periods.

BIODIVERSITY ASSESSMENT OF MICROORGANISMS ASSOCIATED WITH TWO MARINE SPONGES (Haliclona oculata AND Amphius huxleyi) COLLECTED AT THE LANG CO BAY OF VIETNAM

Sponges (Phylum Porifera) are ancient sedentary and filter-feeding animals which harbour very diverse and abundant associated microbial community in their tissues with density up to 40–50% of sponge tissue volume. In this study, the diversity of associated microorganisms with two marine sponges Haliclona oculata and Amphius huxleyi collected at the Lang Co bay of Vietnam was assessed by analysis of hypervariable V3 and V4 regions of the 16S rRNA gene using Illumina MiSeq system. The taxonomic diversity of sponge-associated microorganisms was classified to different taxonomic levels (kingdom, phylum, class, order, family, and genus). Based on Bayesian classification method and reference sequences derived from Greengenes database, the associated microorganisms in studied sponges were assigned to 17 phyla (H. oculata) and 13 phyla (A. huxleyi). Many microbial taxa were detected in two sponge species, however, they were distinctive by the abundance. Proteobacteria was the most dominant phylum in both sponge species, and all of 4 classes Epsilonproteobacteria, Gammaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria were found in H. oculata and A. huxleyi.