RESUMO
Ascidians are prolific colonizers of new environments and possess a range of well-studied features that contribute to their successful spread, but the role of their symbiotic microbial communities in their long-term establishment is mostly unknown. In this study, we utilized next-generation amplicon sequencing to provide a comprehensive description of the microbiome in the colonial ascidian Clavelina oblonga and examined differences in the composition, diversity, and structure of symbiont communities in the host's native and invasive ranges. To identify host haplotypes, we sequenced a fragment of the mitochondrial gene cytochrome c oxidase subunit I (COI). C. oblonga harbored a diverse microbiome spanning 42 bacterial and three archaeal phyla. Colonies in the invasive range hosted significantly less diverse symbiont communities and exhibited lower COI haplotype diversity than colonies in the native range. Differences in microbiome structure were also detected across colonies in the native and invasive range, driven largely by novel bacteria representing symbiont lineages with putative roles in nitrogen cycling. Variability in symbiont composition was also observed among sites within each range. Together, these data suggest that C. oblonga hosts a dynamic microbiome resulting from (i) reductions in symbiont diversity due to founder effects in host populations and (ii) environmental selection of symbiont taxa in response to new habitats within a range. Further investigation is required to document the mechanisms behind these changes and to determine how changes in microbiome structure relate to holobiont function and the successful establishment of C. oblonga worldwide.IMPORTANCE Nonnative species destabilize coastal ecosystems and microbial symbionts may facilitate their spread by enhancing host survival and fitness. However, we know little of the microorganisms that live inside invasive species and whether they change as the host spreads to new areas. In this study, we investigated the microbial communities of an introduced ascidian (Clavelina oblonga) and tracked symbiont changes across locations within the host's native and invasive ranges. Ascidians in the invasive range had less-diverse microbiomes, as well as lower host haplotype diversity, suggesting that specific colonies reach new locations and carry select symbionts from native populations (i.e., founder effects). Further, ascidians in the invasive range hosted a different composition of symbionts, including microbes with the potential to aid in processes related to invasion success (e.g., nutrient cycling). We conclude that the putative functionality and observed flexibility of this introduced ascidian microbiome may represent an underappreciated factor in the successful establishment of nonnative species in new environments.
Assuntos
Espécies Introduzidas , Microbiota , Urocordados/microbiologia , Animais , Bactérias/genética , Brasil , Código de Barras de DNA Taxonômico , Florida , Itália , North Carolina , RNA Ribossômico 16S/genética , Água do Mar , South Carolina , Espanha , Simbiose , Urocordados/genéticaRESUMO
Marine natural product drug discovery has begun to play an important role in the treatment of disease, with several recently approved drugs. In addition, numerous microbial natural products have been discovered from members of the order Actinomycetales, particularly in the genus Streptomyces, due to their metabolic diversity for production of biologically active secondary metabolites. However, many secondary metabolites cannot be produced under laboratory conditions because growth conditions in flask culture differ from conditions in the natural environment. Various experimental conditions (e.g., mixed fermentation) have been attempted to increase yields of previously described metabolites, cause production of previously undetected metabolites, and increase antibiotic activity. Adult ascidians-also known as tunicates-are sessile marine invertebrates, making them vulnerable to predation and therefore are hypothesized to use host-associated bacteria that produce biologically active secondary metabolites for chemical defense. A marine-derived Streptomyces sp. strain PTY087I2 was isolated from a Panamanian tunicate and subsequently co-cultured with human pathogens including Bacillus subtilis, methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa, followed by extraction. Co-culture of Streptomyces sp. PTY087I2 with each of these human pathogens resulted in increased production of three antibiotics: granaticin, granatomycin D, and dihydrogranaticin B, as well as several analogues seen via molecular networking. In addition, co-cultures resulted in strongly enhanced biological activity against the Gram positive human pathogens used in these experiments. Expanded utilization of co-culture experiments to allow for competitive interactions may enhance metabolite production and further our understanding of these microbial interactions.
Assuntos
Antibacterianos/farmacologia , Hidrocarbonetos Cíclicos/isolamento & purificação , Streptomyces/química , Animais , Antibacterianos/isolamento & purificação , Técnicas de Cocultura , Humanos , Biologia Marinha , Staphylococcus aureus Resistente à Meticilina/metabolismo , Testes de Sensibilidade Microbiana , Naftoquinonas/isolamento & purificação , Panamá , Pseudomonas aeruginosa/metabolismo , Regulação para Cima/efeitos dos fármacos , Urocordados/microbiologiaRESUMO
A novel actinobacterium, designated isolate B204(T), was isolated from a marine ascidian Didemnum sp., collected from São Paulo, Brazil, and its taxonomic position established using data from a polyphasic study. The organism showed a combination of chemotaxonomic and morphological characteristics consistent with its classification in the genus Gordonia and formed a distinct phyletic line in the Gordonia 16S rRNA gene tree. It was closely related to Gordonia terrae DSM 43249(T) (99.9 % 16S rRNA gene sequence similarity) and Gordonia lacunae DSM 45085(T) (99.3 % 16S rRNA gene sequence similarity) but was distinguished from these strains by a moderate level of DNA-DNA relatedness (63.0 and 54.7 %) and discriminatory phenotypic properties. Based on the data obtained, the isolate B204(T) (=CBMAI 1069(T) = DSM 46679(T)) should therefore be classified as the type strain of a novel species of the genus Gordonia, for which the name Gordonia didemni sp. nov. is proposed.
Assuntos
Actinobacteria/isolamento & purificação , Água do Mar/microbiologia , Urocordados/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Animais , Brasil , DNA Bacteriano/genética , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
We investigated the bacterial accumulation and digestion capability of Polyandrocarpa zorritensis, a non-indigenous colonial ascidian originally described in Peru and later found in the Mediterranean. Microbiological analyses were carried out on homogenates from "unstarved" and "starved" ascidians and seawater from the same sampling site (Adriatic Sea, Italy). Culturable heterotrophic bacteria (22 °C), total culturable bacteria (37 °C) and vibrios abundances were determined on Marine Agar 2216, Plate Count Agar and TCBS Agar, respectively. Microbial pollution indicators were measured by the most probable number method. All the examined microbiological groups were accumulated by ascidians but differently digested. An interesting outcome is the capability of P. zorritensis to digest allochthonous microorganisms such as coliforms as well as culturable bacteria at 37 °C, counteracting the effects of microbial pollution. Thus, the potential exploitation of these filter feeders to restore polluted seawater should be taken into consideration in the management of this alien species.
Assuntos
Água do Mar/microbiologia , Urocordados/microbiologia , Microbiologia da Água , Animais , Meio Ambiente , Espécies Introduzidas , Itália , PeruRESUMO
The cytotoxic activity at 50 µg/ml of extracts obtained from eleven fungal strains associated to Eudistoma vannamei, an endemic ascidian from Northeast Brazil, against two cell lines, i.e., the HCT-8 (colon cancer) and the MDA-MB-435 (melanoma) cell lines, was investigated. The most promising extract (EV10) was obtained from a fungus identified as Aspergillus sp. by molecular analysis and was selected for bioassay-guided isolation of its active principals. Large-scale fermentation of EV10 in potato-dextrose broth followed by chromatographic purification of the active extract from the liquid medium allowed the isolation of the isocoumarins mellein, cis-4-hydroxymellein, and trans-4-hydroxymellein, besides penicillic acid. All isolated compounds were tested for their cytotoxicity against the tumor cell lines MDA-MB-435 and HCT-8 and revealed penicillic acid as the only cytotoxic compound (cell growth inhibitions >95%).
Assuntos
Fungos/química , Urocordados/microbiologia , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Fungos/isolamento & purificação , Humanos , Isocumarinas/química , Isocumarinas/isolamento & purificação , Isocumarinas/toxicidade , Ocratoxinas/química , Ocratoxinas/isolamento & purificação , Ocratoxinas/toxicidade , Ácido Penicílico/química , Ácido Penicílico/isolamento & purificação , Ácido Penicílico/toxicidadeRESUMO
Little is known about the microbial diversity associated with marine macroorganisms, despite the vital role microorganisms may play in marine ecosystems. The aim of the present study was to investigate the diversity of bacteria and fungi isolated from eight marine invertebrate and one algae samples. Data derived from ARDRA and sequencing analyses allowed the identification of marine-derived microorganisms isolated from those samples. Microbial strains identified up to the genus level revealed 144 distinct ribotypes out of 256 fungal strains and 158 distinct ribotypes out of 181 bacterial strains. Filamentous fungi were distributed among 24 different genera belonging to Ascomycota, Zygomycota and Basidiomycota, some of which had never been reported in the literature as marine invertebrate-inhabiting fungi (Pestalotiopsis, Xylaria, Botrysphaeria and Cunnninghamella). Bacterial isolates were affiliated to 41 different genera, being Bacillus, Ruegeria, Micrococcus, Pseudovibrio and Staphylococcus the most abundant ones. Results revealed an unexpected high microbial diversity associated to the macroorganisms which have been collected and suggested the selection of certain microbial taxonomic groups according to the host. The combined data gathered from this investigation contribute to broaden the knowledge of microbial diversity associated to marine macroorganisms, including as a promising source for the discovery of new natural products.