Chemical defence against predators in a sub-Arctic fjord

The development of chemical defences in marine organisms is supposed to be driven by intense pressure of predation and competition. While benthic communities in tropical and also Antarctic regions are thought to be mainly structured by intra- and interspecific interactions, these factors are proposed to be less important in northern high latitudes. Consequently, selective pressure for chemical defence should be low in these regions. To investigate the incidence of chemical defence against predation in northern high latitudes, crude extracts of 18 abundant sessile or slow-moving invertebrate species (4 sponges, 3 actinians, 1 soft coral, 4 bryozoans, 3 ascidians and the egg mass of a gastropod) from Kongsfjord (Spitsbergen) were tested for feeding deterrent activity. Laboratory assays were performed by offering artificial food with extracts to two different predators, the amphipod Anonyx nugax which is a common species in Kongsfjord, and the starfish Asterias rubens from the North Sea. Of the 18 extracts tested, 2 (Haliclona viscosa, Hormathia nodosa) exhibited significant feeding deterrent effects in the amphipod assay. Furthermore, 6 extracts had a significantly stimulating effect on the amphipod feeding, and 10 extracts did not affect consumption. In the starfish assay, only the crude extract of H. viscosa was significantly rejected. For H. viscosa, feeding deterrence could be established for two pure compounds, and for H. nodosa for one fraction. The present data show that feeding deterrent compounds are present in sub-Arctic marine invertebrates from Kongsfjord but are less abundant than in temperate, tropical and Antarctic species.     

Antibacterial and antilarval activity of deep-sea bacteria from sediments of the West Pacific Ocean

Abstract

Deep-sea microorganisms are a new source of bioactive compounds. In this study, crude ethyl acetate extracts of 176 strains of deep-sea bacteria, isolated from sediments of the West Pacific Ocean, were screened for their antibacterial activity against four test bacterial strains isolated from marine biofilms. Of these, 28 deep-sea bacterial strains exhibited antibacterial activity against one or more of the bacteria tested. Active deep-sea bacterial strains belonged mainly to the genera of Pseudomonas, Psychrobacter and Halomonas. Additionally, antilarval activity of 56 deep-sea bacterial strains was screened using Balanus amphitrite larvae. Seven bacterial strains produced metabolites that had strong inhibitive effects on larval settlement. None of these metabolites showed significant toxicity. The crude extract of one deep-sea Streptomyces strain could completely inhibit larval settlement at a concentration of 25 μg ml^?1.     

Antibacterial and antilarval activity of deep-sea bacteria from sediments of the West Pacific Ocean

Deep-sea microorganisms are a new source of bioactive compounds. In this study, crude ethyl acetate extracts of 176 strains of deep-sea bacteria, isolated from sediments of the West Pacific Ocean, were screened for their antibacterial activity against four test bacterial strains isolated from marine biofilms. Of these, 28 deep-sea bacterial strains exhibited antibacterial activity against one or more of the bacteria tested. Active deep-sea bacterial strains belonged mainly to the genera of Pseudomonas, Psychrobacter and Halomonas. Additionally, antilarval activity of 56 deep-sea bacterial strains was screened using Balanus amphitrite larvae. Seven bacterial strains produced metabolites that had strong inhibitive effects on larval settlement. None of these metabolites showed significant toxicity. The crude extract of one deep-sea Streptomyces strain could completely inhibit larval settlement at a concentration of 25 microg ml(-1).     

An evaluation of the antimicrobial properties of the eggs of 11 species of scleractinian corals

Potential sources of mortality of marine invertebrate larvae are numerous and include predation and diseases caused by marine microorganisms. Extracts from the eggs of 11 coral species were evaluated for their ability to deter surface attachment and inhibit the growth of two marine tolerant laboratory bacteria and 92 bacterial strains isolated from seawater and the surface of coral colonies on the Great Barrier Reef (GBR). Extracts of the eggs of Montipora digitata inhibited the growth of the two laboratory bacteria, Vibrio harveyii and Bacillus subtilis, and one bacterial isolate from the mucus of the coral Favia pallida in disc diffusion and liquid culture assays. No other microbial strains (n=91) from the surface of corals and the reef environment were inhibited by M. digitata extracts. No antibacterial activity was found in the egg extracts of the remaining ten coral species and none of the extracts inhibited surface attachment of various bacteria. Extrapolation of estimated surface concentrations of the biologically active extract of M. digitata suggests that the level of the growth inhibitory compounds may be sufficient to deter microbial growth in situ.     

Investigation of Chondrus crispus as a potential source of new antifouling agents

The search for environment-friendly and non-toxic antifouling (AF) paint components has led to the investigation of natural products from seaweeds. The defence metabolites used by algae to deter unwanted epibiosis have potential for harnessing and use in AF applications. Crude algal extracts may provide a suitable mixture of compounds with AF potency. Crude ethanol extracts of the macroalgae Chondrus crispus (Rhodophyceae), from both dried and fresh sources were tested and compared using bioassays based on five marine bacterial strains, five phytoplankton strains and two macroalgae to assess the AF efficacy. Dried extract from the algae had a lower minimum inhibitory concentration at 25 μg mL⁻¹ against the growth of bacteria and phytoplankton species than that from the fresh source. Macroalgae tests indicated that the extracts had an anti-germination activity 25–50 μg mL⁻¹ against both Undaria pinnatifida and Ulva intestinalis spores. A field trial of AF paint incorporating crude extract indicated an initial AF potency lasting six weeks.     

Comparison of antifouling properties of native and invasive Sargassum (Fucales,Phaeophyceae) species

The invasiveness of algal species can be facilitated by chemo-ecological traits that allow the establishment of invasive species in a highly competitive environment. Anti-bacterial, anti-quorum sensing, anti-diatom and anti-larval properties of the invasive brown macroalga Sargassum muticum and three native Sargassum species from Oman waters were compared in laboratory and field experiments to assess whether these traits have the potential to facilitate the invasion process. Only the extract of S. muticum inhibited bacterial growth of four marine bacterial strains and quorum sensing in the reporter strain Chromobacterium violaceum CV017. Settlement, growth and survival of the diatom Cylindrotheca closterium and larvae of the bryozoan Bugula neritina were significantly inhibited by all Sargassum extracts in laboratory experiments. However, crude extracts of S. muticum had the strongest antifouling effect. Natural tissue-level concentrations of S. muticum extract reduced diatom density to about 20% compared with the controls. Larval mortality increased by 80–90% compared with controls with S. muticum extract diluted to one-third natural levels. Significant anti-diatom activity of S. muticum was confirmed in the field experiments with Sargassum extracts embedded in a phytagel matrix. Comparison of non-polar compounds by gas chromatography–mass spectrometry demonstrated that S. muticum extracts had overall fewer secondary metabolites but more species-unique compounds than extracts of native Sargassum spp. The greater antifouling defence of invasive vs. native Sargassum species indicates a selective trait that may contribute to the invasion success of S. muticum.     

Antifouling Potential of Some Marine Organisms from India Against Species of Bacillus and Pseudomonas

Crude methanolic extracts of 37 marine organisms (16 species of flora, 21 species of fauna) were screened for antibacterial properties against 5 strains of bacteria isolated from marine environments. Of these, 10 plant and 9 animal extracts exhibited antibacterial activity against at least one bacterial strain. The extracts of 6 species were active against all the strains: i.e., Stoechospermum marginatum (brown algae), Cymodocea rotundata (seagrass), Petrosia sp. and Psammaplysilla purpurea (sponges), Sinularia compressa (soft coral), and Cassiopeia sp. (jellyfish). Among the plants, Padina tetrastromatica (brown algae) extract exhibited significant activity (9–11-mm inhibition zone at 500 μg per 6-mm disc) against Bacillus pumilus and Pseudomonas vesicularis, while the extracts of Petrosia, Psammaplysilla, and Cassiopeia were strongly active (11–13-mm inhibition zone at 500 μg per 6-mm disc) against B. circulans and P. putida. It was further confirmed that the attachment of bacterial strains on glass slides was inhibited remarkably with increasing concentrations of bioextracts of Petrosia sp. and Psammaplysilla purpurea. The present findings could form the basis for exploring the antibacterial potential of bioactive molecules from some of the marine organisms that exhibited moderate to strong antibacterial properties.     

Screening of Antimicrobials from Caribbean Sea Animals and Isolation of Bactericidal Proteins from the Littoral Mollusk <Emphasis Type="Italic">Cenchritis muricatus</Emphasis>

Marine organisms represent approximately half of the world’s biodiversity by virtue of the sea being an immense reservoir of bioactive molecules. Here, antimicrobial crude extract activities of different marine invertebrates from the Caribbean Sea were evaluated. One of the most active, crude extracts was that marine snail Cenchritis muricatus, it was capable of totally inhibiting the development of Staphylococcus aureus and also showed a growth inhibition of 95.9% in Escherichia coli. Aiming to isolate molecules that confirm antimicrobial activity, the crude extract was purified by reversed-phase HPLC C-18 chromatography. Thereafter, one of the obtained fractions preserved this antibacterial activity. Furthermore, SDS-PAGE analysis (15%) showed the presence of two proteins of molecular masses with approximately 10 and 15 kDa, respectively. The first 19 amino acids of both proteins were sequenced by using Edman degradation, yielding unidentified primary structures compared against sequences deposited at NCBI databank. This is the first report of antibacterial proteins isolated from the mollusk Cenchritis muricatus and these proteins could be used as antibiotic alternatives in the aquacultural industry, as well as in agricultural or biomedical research.     

Antibacterial activities of anthozoan corals on some marine microfoulers

The antibacterial activities of twelve species of anthozoans (4 gorgonians, 5 soft corals and 3 antipatharians) collected off the east coast of India were assayed against four dominant marine fouling bacterial strains isolated from the biofilm of fouled aluminium panels. Of the 48 combinations (12 corals x 4 bacteria) eighteen interactions showed antibacterial activity (37.5%). Such activity was most apparent in gorgonians, which inhibited bacterial growth in ten out of sixteen interactions (62.5%) compared with that of five out of twenty interactions (25%) among soft corals and three out of twelve interactions (25%) among antipatharians. The activity scores varied with different extracts and test organisms used, and was highest in antipatharians. Among the four bacterial strains Vibrio sp. was the least sensitive (2/12) when compared with Flavobacterium sp. (6/12). This is the first report of antibacterial activities of antipatharian colonies against marine microfoulers. The results imply that anthozoan corals harbour potent agents which could be exploited for the development of antifouling technology.     

Screening for antibacterial and antifungal activities in marine benthic invertebrates from northern Norway

Benthic marine invertebrates collected from sub-Arctic regions of northern Norway, were found to be a promising source of novel bioactive compounds against human and fish pathogenic bacteria and fungi. Lyophilized material from seven species of ascidians, six sponges and one soft alcyonid coral were extracted with 60% acidified acetonitrile (ACN). After separation into an ACN-rich phase (ACN-extract) and an aqueous phase, and subsequent solid-phase extraction of the aqueous phase, fractions differing in polarity were obtained and screened for antibacterial and antifungal activities, along with the more lipophilic ACN-extracts. Antimicrobial activity was determined against two Gram-negative, two Gram-positive bacteria, and two strains of fungi. Notably, all the invertebrate species in the study showed activity against all four strains of bacteria and the two strains of fungi. In general, the aqueous fractions displayed highest antimicrobial activity, and the most potent extracts were obtained from the colonial ascidian Synoicum pulmonaria which displayed activity against bacteria and fungi at a concentration of 0.02 mg/ml; the lowest concentration tested.     

Identification of rosmarinic acid and sulfated flavonoids as inhibitors of microfouling on the surface of eelgrass Zostera marina

A bioassay-guided approach was used to identify defense compounds that are present on the surface of Zostera marina and which inhibit settlement of microfoulers at natural concentrations. Moderately polar eelgrass surface extracts inhibited the settlement of seven marine bacteria and one yeast that originated from non-living substrata. In contrast, five other bacterial strains that had been directly isolated from eelgrass surfaces were all insensitive, which suggested a selective effect of surface metabolites on the microbial communities present on eelgrass. Bioassay-guided isolation of active compounds from the extracts in combination with UPLC-MS and ¹H-NMR spectroscopy resulted in the identification of rosmarinic acid, luteolin-7-sulfate and diosmetin-7-sulfate or its isomer chrysoeriol-7-sulfate. All three compounds are nontoxic repellents, as they did not inhibit bacterial growth, but prevented bacterial settlement in a dose-dependent manner. Between 15.6 and 106.8 μg ml^?1 of rosmarinic acid were present on the eelgrass surface, enough for half maximal settlement inhibition of bacteria.     

Antidiatom and antibacterial activity of epiphytic bacteria isolated from <Emphasis Type="Italic">Ulva</Emphasis><Emphasis Type="Italic">lactuca</Emphasis> in tropical waters

Bacteria and diatoms are primary colonizers of marine surfaces and hence play a crucial role in the attachment and subsequent growth of macroorganisms. It has been suggested that the temperate green alga Ulva lactuca relies on the defence provided by the epiphytic bacterial community to regulate surface fouling of colonising organisms. In this study, ten resident bacterial isolates from tropical U. lactuca were tested for their antibacterial and antidiatom properties that may regulate surface colonization on the algae. Sixty percent of the epiphytic isolates expressed antibacterial properties against other resident bacteria and 80% had antidiatom activity against the pennate diatom, Cylindrotheca fusiformis. Isolates of the Pseudoalteromonas genus showed both- antibacterial and antidiatom activities, while members of the genus Bacillus, Vibrio and Shewanella mostly possessed antidiatom activity. Our results show that a high proportion of bacterial isolates from tropical U. lactuca, like that of their temperate counterparts contain antibiotic properties that might impact on the bacterial community composition and prevent fouling by diatoms.     

In vitro evaluation of Datura innoxia (thorn-apple) for potential antibacterial activity

Various parts of Datura innoxia were examined for potential antibacterial activity by preparing their crude aqueous and organic extracts against Gram-negative bacteria (Escherichia coli and Salmonella typhi) and Gram-positive bacteria (Bacillus cereus, Bacillus subtilis and Staphylococcus aureus). The results of agar well diffusion assay indicated that the pattern of inhibition depends largely upon the plant part, solvent used for extraction and the organism tested. Extracts prepared from leaves were shown to have better efficacy than stem and root extracts. Organic extracts provided potent antibacterial activity as compared to aqueous extracts. Among all the extracts, methanolic extract was found most active against almost all the bacterial species tested. Gram-positive bacteria were found most sensitive as compared to Gram-negative bacteria. Staphylococcus aureus was signifi cantly inhibited by almost all the extracts even at very low MIC followed by other Gram-positives. For Escherichia coli (a Gram-negative bacterium), the end point was not reached for ethyl acetate extract while it was very high for other extracts. The study promises an interesting future for designing a potentially active antibacterial agent from Datura innoxia.     

Intraspecific diversity in the fungal speciesChaunopycnis alba: Implications for microbial screening programs

Intraspecific variation among 84 isolates of the anamorphic fungusChaunopycnis alba from 26 different geographical locations was analyzed by investigating optimal growth temperatures, differences in the production of secondary metabolites and presence or absence of the cyclosporin synthetase gene. The genetic diversity was assessed using random amplified polymorphic DNA (RAPD). Analysis of these data showed high genetic, metabolic and physiological diversity within this species. Isolates from the Antarctic represented the most homogeneous group withinC. alba and together with isolates from the Arctic these polar strains differed from alpine, temperate and tropical strains by low optimal growth temperatures and by low production of secondary metabolites. Isolates from tropical climes were characterized by high optimal growth temperatures and by the production of comparatively diverse metabolite spectra. Most of the isolates that were similar in the combination of their physiological and metabolic characters were also genetically related. Isolates from different geographical origins did not show many similarities, with the exception of the cyclosporin A-producing isolates, and large diversity could be observed even within a single habitat. This leads us to the suggestion that for pharmaceutical screening programs samples should be collected from a diversity of different geographical and climatic locations. For the selection of strains for screening the RAPD assay seems to be the most powerful tool. It reflected the highest intraspecific diversity and the results corresponded well with the other characteristics.     

Diversity and antibacterial activity of bacteria isolated from the coastal marine sponges Amphilectus fucorum and Eurypon major

Aims: To assess the diversity and antimicrobial activity of culturable bacteria associated with two temperate‐water marine sponges, Amphilectus fucorum and Eurypon major. Methods and Results: Sponge samples were collected in August 2008 and bacteria were cultured on several different media. The 16S rRNA gene of representative strains was sequenced to allow classification. It was found that Proteobacteria were the dominant group of bacteria cultured from both sponges, but overall, the bacterial composition was diverse and distinct between the sponges. The most notable features were the significantly higher proportion of firmicutes in E. major and the low frequency of actinobacteria in both sponges. Four bacterial isolates were identified as potentially novel species and will be characterised in future studies. Approximately 400 cultured bacteria were screened for antimicrobial activity against a collection of indicator strains, with only eight strains, all Pseudovibrio spp., displaying any such activity. These strains were active against Escherichia coli and Bacillus subtilis but not Staphylococcus aureus or a selection of fungal strains. Conclusions: Diverse and distinct populations of culturable bacteria are present in the coastal sponges A. fucorum and E. major. Only a minority of isolates produce antibacterial metabolites in culture, but this activity is common in Pseudovibrio spp. Significance and Impact of the Study: This study illustrates the diversity of sponge‐associated bacteria and the need to increase our knowledge about the function of these symbiotic bacteria. The data suggest that production of antibacterial metabolites is restricted to a subset of species, with the majority involved in other functions. The importance of Pseudovibrio as a reservoir of antibacterial metabolites is also highlighted.     

Bioactivity,Chemical Profiling,and 16S rRNA-Based Phylogeny of <Emphasis Type="BoldItalic">Pseudoalteromonas</Emphasis> Strains Collected on a Global Research Cruise

One hundred one antibacterial Pseudoalteromonas strains that inhibited growth of a Vibrio anguillarum test strain were collected on a global research cruise (Galathea 3), and 51 of the strains repeatedly demonstrated antibacterial activity. Here, we profile secondary metabolites of these strains to determine if particular compounds serve as strain or species markers and to determine if the secondary metabolite profile of one strain represents the bioactivity of the entire species. 16S rRNA gene similarity divided the strains into two primary groups: One group (51 strains) consisted of bacteria which retained antibacterial activity, 48 of which were pigmented, and another group (50 strains) of bacteria which lost antibacterial activity upon sub-culturing, two of which were pigmented. The group that retained antibacterial activity consisted of six clusters in which strains were identified as Pseudoalteromonas luteoviolacea, Pseudoalteromonas aurantia, Pseudoalteromonas phenolica, Pseudoalteromonas ruthenica, Pseudoalteromonas rubra, and Pseudoalteromonas piscicida. HPLC-UV/VIS analyses identified key peaks, such as violacein in P. luteoviolacea. Some compounds, such as a novel bromoalterochromide, were detected in several species. HPLC-UV/VIS detected systematic intra-species differences for some groups, and testing several strains of a species was required to determine these differences. The majority of non-antibacterial, non-pigmented strains were identified as Pseudoalteromonas agarivorans, and HPLC-UV/VIS did not further differentiate this group. Pseudoalteromonas retaining antibacterial were more likely to originate from biotic or abiotic surfaces in contrast to planktonic strains. Hence, the pigmented, antibacterial Pseudoalteromonas have a niche specificity, and sampling from marine biofilm environments is a strategy for isolating novel marine bacteria that produce antibacterial compounds.     

Gram-Positive Marine Bacteria as a Potential Resource for the Discovery of Quorum Sensing Inhibitors

Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive isolates from diverse habitats were tested for their ability to interfere with Vibrio harveyi bioluminescence, a cell signaling-regulated phenotype. Rapid assay methods were employed where environmental isolates were propagated alongside the reporter strain. “Actives” were defined as bacteria that interfered with bioluminescence without visible cell-killing effects (antibiotic activity). A total of 49 bacterial isolates interfered with bioluminescence production in the assays. Metabolite extracts were generated from cultures of the active isolates, and 28 reproduced the bioluminescence inhibition against V. harveyi. Of those 28, five extracts additionally inhibited violacein production by Chromobacterium violaceum. Chemical investigations revealed that phenethylamides and a cyclic dipeptide are two types of secondary metabolites responsible for the observed activities. The active bacterial isolates belonged primarily to either the genus Bacillus or Halobacillus. The results suggest that Gram-positive marine bacteria are worthy of further investigation for the discovery of quorum sensing antagonists.     

Allelochemicals produced by Caribbean macroalgae and cyanobacteria have species-specific effects on reef coral microorganisms

Coral populations have precipitously declined on Caribbean reefs while algal abundance has increased, leading to enhanced competitive damage to corals, which likely is mediated by the potent allelochemicals produced by both macroalgae and benthic cyanobacteria. Allelochemicals may affect the composition and abundance of coral-associated microorganisms that control host responses and adaptations to environmental change, including susceptibility to bacterial diseases. Here, we demonstrate that extracts of six Caribbean macroalgae and two benthic cyanobacteria have both inhibitory and stimulatory effects on bacterial taxa cultured from the surfaces of Caribbean corals, macroalgae, and corals exposed to macroalgal extracts. The growth of 54 bacterial isolates was monitored in the presence of lipophilic and hydrophilic crude extracts derived from Caribbean macroalgae and cyanobacteria using 96-well plate bioassays. All 54 bacterial cultures were identified by ribotyping. Lipophilic extracts from two species of Dictyota brown algae inhibited >50% of the reef coral bacteria assayed, and hydrophilic compounds from Dictyota menstrualis particularly inhibited Vibrio bacteria, a genus associated with several coral diseases. In contrast, both lipo- and hydrophilic extracts from 2 species of Lyngbya cyanobacteria strongly stimulated bacterial growth. The brown alga Lobophora variegata produced hydrophilic compounds with broad-spectrum antibacterial effects, which inhibited 93% of the bacterial cultures. Furthermore, bacteria cultured from different locations (corals vs. macroalgae vs. coral surfaces exposed to macroalgal extracts) responded differently to algal extracts. These results reveal that extracts from macroalgae and cyanobacteria have species-specific effects on the composition of coral-microbial assemblages, which in turn may increase coral host susceptibility to disease and result in coral mortality.     

Overview of the chemical ecology of benthic marine invertebrates along the western Antarctic peninsula

Thirteen years ago in a review that appeared in the American Zoologist, we presented the first survey of the chemical and ecological bioactivity of Antarctic shallow-water marine invertebrates. In essence, we reported that despite theoretical predictions to the contrary the incidence of chemical defenses among sessile and sluggish Antarctic marine invertebrates was widespread. Since that time we and others have significantly expanded upon the base of knowledge of Antarctic marine invertebrates' chemical ecology, both from the perspective of examining marine invertebrates in new, distinct geographic provinces, as well as broadening the evaluation of the ecological significance of secondary metabolites. Importantly, many of these studies have been framed within established theoretical constructs, particularly the Optimal Defense Theory. In the present article, we review the current knowledge of chemical ecology of benthic marine invertebrates comprising communities along the Western Antarctic Peninsula (WAP), a region of Antarctica that is both physically and biologically distinct from the rest of the continent. Our overview indicates that, similar to other regions of Antarctica, anti-predator chemical defenses are widespread among species occurring along the WAP. In some groups, such as the sponges, the incidence of chemical defenses against predation is comparable to, or even slightly higher than, that found in tropical marine systems. While there is substantial knowledge of the chemical defenses of benthic marine invertebrates against predators, much less is known about chemical anti-foulants. The sole survey conducted to date suggests that secondary metabolites in benthic sponges are likely to be important in the prevention of fouling by benthic diatoms, yet generally lack activity against marine bacteria. Our understanding of the sensory ecology of Antarctic benthic marine invertebrates, despite its great potential, remains in its infancy. For example, along the WAP, community-level non-consumptive effects occur when amphipods chemically sense fish predators and respond by seeking refuge in chemically-defended macroalgae. Such interactions may be important in releasing amphipods from predation pressure and facilitating their unusually high abundances along the WAP. Moreover, recent studies on the sensory biology of the Antarctic keystone sea star Odontaster validus indicate that chemotactile-mediated interactions between conspecifics and other sympatric predatory sea stars may have significant ramifications in structuring community dynamics. Finally, from a global environmental perspective, understanding how chemical ecology structures marine benthic communities along the WAP must increasingly be viewed in the context of the dramatic impacts of rapid climatic change now occurring in this biogeographic region.     

Antiangiogenic, Antimicrobial, and Cytotoxic Potential of Sponge-Associated Bacteria

The bacteria associated with marine invertebrates are a rich source of bioactive metabolites. In the present study bacteria associated with the sponge Suberites domuncula and its primmorphs (3-dimensional aggregates containing proliferating cells) were isolated and cultured. These bacteria were extracted, and the extracts were assayed for antiangiogenic, hemolytic, antimicrobial, and cytotoxic activities. Our studies revealed that extract obtained from the bacterium (PB2) isolated from sponge primmorphs is a potent angiogenesis inhibitor. In the chick chorio-allantoic membrane (CAM) assay, it showed 50% activity at 5 μg ml⁻¹ and 100% activity at 10 and 20 μg ml⁻¹ concentrations. Extracts obtained from 5 bacterial strains isolated from sponge and its primmorphs showed hemolytic activity. The sponge-associated bacteria belonging to the α subdivision of Proteobacteria and the primmorph-associated bacterium identified as a possible novel Pseudomonas sp. displayed remarkable antimicrobial activity. It is important to note that these bacterial extracts were strongly active against multidrug-resistant clinical strains such as Staphylococcus aureus and Staphylococcus epidermidis, isolated from hospital patients. The bacterial extracts having antimicrobial activity also showed cytotoxicity against HeLa and PC12 cells. In summary, this investigation explores the importance of sponge-associated bacteria as a valuable resource for the discovery of novel bioactive molecules.