Antimicrobial activity of heterotrophic bacterial communities from the marine sponge Erylus discophorus (Astrophorida, Geodiidae)

10 páginas, 3 tablas.Heterotrophic bacteria associated with two specimens of the marine sponge Erylus discophorus were screened for their capacity to produce bioactive compounds against a panel of human pathogens (Staphylococcus aureus wild type and methicillin-resistant S. aureus (MRSA), Bacillus subtilis, Pseudomonas aeruginosa, Acinetobacter baumanii, Candida albicans and Aspergillus fumigatus), fish pathogen (Aliivibrio fischeri) and environmentally relevant bacteria (Vibrio harveyi). The sponges were collected in Berlengas Islands, Portugal. Of the 212 isolated heterotrophic bacteria belonging to Alpha- and Gammaproteobacteria, Actinobacteria and Firmicutes, 31% produced antimicrobial metabolites. Bioactivity was found against both Gram positive and Gram negative and clinically and environmentally relevant target microorganisms. Bioactivity was found mainly against B. subtilis and some bioactivity against S. aureus MRSA, V. harveyi and A. fisheri. No antifungal activity was detected. The three most bioactive genera were Pseudovibrio (47.0%), Vibrio (22.7%) and Bacillus (7.6%). Other less bioactive genera were Labrenzia, Acinetobacter, Microbulbifer, Pseudomonas, Gordonia, Microbacterium, Micrococcus and Mycobacterium, Paenibacillus and Staphylococcus. The search of polyketide I synthases (PKS-I) and nonribosomal peptide synthetases (NRPSs) genes in 59 of the bioactive bacteria suggested the presence of PKS-I in 12 strains, NRPS in 3 strains and both genes in 3 strains. Our results show the potential of the bacterial community associated with Erylus discophorus sponges as producers of bioactive compounds.This research was supported by the European Regional Development Fund (ERDF) through the COMPETE - Operational Competitiveness Programme and national funds through FCT – Foundation for Science and Technology, under the projects PEst-C/MAR/LA0015/2013, PEst-OE/QUI/UI0612/2011 and PTDC/ QUI-QUI/098053/2008. Ana Patrícia Graçaa acknowledges an ERAMUS fellowship. Joana Bondoso was financed by FCT - Foundation for Science and Technology (PhD grant SFRH/BD/35933/2007). Joana R. Xavier’s research is funded by an FCT - Foundation for Science and Technology postdoctoral fellowship (grant no. SFRH/BPD/62946/2009). In addition, this work was funded by the Fundación MEDINA, a public-private partnership of Merck Sharp and Dohme of España/ Universidad de Granada/Junta de AndalucíaPeer reviewe

Abundance and bioactivity of cultured sponge-associated bacteria from the Mediterranean Sea

In this study, the search for new antibiotics was combined with quantitative ecological studies. The cultured fraction of the associated bacterial communities from ten different Mediterranean sponge species was investigated. To obtain quantitative and qualitative data of sponge-associated bacterial communities and to expand the cultured diversity, different media were used. The largest morphological diversity and highest yield of isolates was obtained by using oligotrophic media, which consisted of natural habitat seawater amended with (1% additional carbon sources. The dominant bacterial morphotypes were determined and bacterial isolates were tested for antimicrobial activity and identified using 16S rDNA sequencing. The sponge-associated most abundant morphotypes were all affiliated to the Alphaproteobacteria and showed antimicrobial activity against at least one of the tested strains. In contrast, the ambient seawater was dominated by Gammaproteobacteria. One single alphaproteobacterium, which was related to Pseudovibrio denitrificans, was shown to dominate the cultured community of at least six of the sponges. This designated MBIC3368-like alphaproteobacterium has been isolated from sponges before and seems to be restricted to associations with members of the phylum Porifera. It displays a weak and unstable antimicrobial activity, which gets easily lost during cultivation. However, this bioactive bacterium was present in the sponges by up to 106 cells per gram wet-weight sponge tissue and dominated the cultured fraction with up to 74%. The association of this alphaproteobacterium with sponges is probably evolutionary young and facultative and possibly involves biologically active secondary metabolites. Besides a demonstrated vertical transfer, additional horizontal transfer between the sponges is assumed. Members of the genus Bacillus displaying antimicrobial activity were found regularly, too. However, actinomycetes, which are known for their production of bioactive substances, were present in very low abundance

Evidence of Unique and Generalist Microbes in Distantly Related Sympatric Intertidal Marine Sponges (Porifera: Demospongiae)

The diversity and specificity of microbial communities in marine environments is a key aspect of the ecology and evolution of both the eukaryotic hosts and their associated prokaryotes. Marine sponges harbor phylogenetically diverse and complex microbial lineages. Here, we investigated the sponge bacterial community and distribution patterns of microbes in three sympatric intertidal marine demosponges, Hymeniacidon perlevis, Ophlitaspongia papilla and Polymastia penicillus, from the Atlantic coast of Portugal using classical isolation techniques and 16S rRNA gene clone libraries. Microbial composition assessment, with nearly full-length 16S rRNA gene sequences (ca. 1400 bp) from the isolates (n = 31) and partial sequences (ca. 280 bp) from clone libraries (n = 349), revealed diverse bacterial communities and other sponge-associated microbes. The majority of the bacterial isolates were members of the order Vibrionales and other symbiotic bacteria like Pseudovibrio ascidiaceiocola, Roseobacter sp., Hahellaceae sp. and Cobetia sp. Extended analyses using ecological metrics comprising 142 OTUs supported the clear differentiation of bacterial community profiles among the sponge hosts and their ambient seawater. Phylogenetic analyses were insightful in defining clades representing shared bacterial communities, particularly between H. perlevis and the geographically distantly-related H. heliophila, but also among other sponges. Furthermore, we also observed three distinct and unique bacterial groups, Betaproteobactria (∼81%), Spirochaetes (∼7%) and Chloroflexi (∼3%), which are strictly maintained in low-microbial-abundance host species O. papilla and P. penicillus. Our study revealed the largely generalist nature of microbial associations among these co-occurring intertidal marine sponges

Deep sequencing reveals diversity and community structure of complex microbiota in five Mediterranean sponges

Marine sponges harbor dense microbial communities of exceptionally high diversity. Despite the complexity of sponge microbiota, microbial communities in different sponges seem to be remarkably similar. In this study, we used a subset of a previously established 454 amplicon pyrosequencing dataset (Schmitt and Taylor, unpublished data). Five Mediterranean sponges were chosen including the model sponge Aplysina aerophoba to determine the extent of uniformity by defining (i) the core microbial community, consisting of bacteria found in all sponges, (ii) the variable microbial community, consisting of bacteria found in 2–4 sponges, and (iii) the species-specific community, consisting of bacteria found in only one sponge. Using the enormous sequencing depth of pyrosequencing the diversity in each of the five sponges was extended to up to 15 different bacterial phyla per sponge with Proteobacteria and Chloroflexi being most diverse in each of the five sponges. Similarity comparison of bacteria on phylum and phylotype level revealed most similar communities in A. aerophoba and A. cavernicola and the most dissimilar community in Pseudocorticium jarrei. A surprising minimal core bacterial community was found when distribution of 97% operational taxonomic units (OTUs) was analyzed. Core, variable, and species-specific communities were comprised of 2, 26, and 72% of all OTUs, respectively. This indicates that each sponge contains a large set of unique bacteria and shares only few bacteria with other sponges. However, host speciesspecific bacteria are probably still closely related to each other explaining the observed similarity among bacterial communities in sponges