Isolation and characterization of a sponge-associated actinomycete that produces manzamines

Two Indonesian sponges, Acanthostrongylophora sp. Sponge 35 and Sponge 52, containing manzamine A were collected off the coast of Manado, Indonesia. Manzamines are a family of marine alkaloids that exhibit a complex molecular architecture and possess bioactivities including antitumour, antimicrobial, antiparasitic and insecticidal activities. Manzamines have been found in 17 different species of sponges with wide geographical distribution which has led to speculation that they may be produced by a microbial symbiont rather than by the sponges themselves. The sponges' microbial communities were investigated using 16S rRNA gene analysis and a rational culture-based microbiology approach in which specific bacterial groups were targeted. The molecular analysis of these microbial communities revealed that they were complex and diverse. Microbiological analyses were conducted on Acanthostrongylophora sp. with a particular emphasis on the isolation of actinomycetes because of the high number of actinomycete sequences in this sponge 16S rRNA gene clone library and their excellent track record as bioactive compound producers. One of the isolated actinomycetes, Micromonospora sp. strain M42, produces manzamine A and 8-hydroxy-manzamine, compounds initially detected in the sponge. A detailed analysis of Micromonospora sp. strain M42 showed that it grew on a wide range of salt concentrations with an optimal growth at 0-1% NaCl. Cultures of Micromonospora sp. strain M42 consistently produced manzamine A with a maximum yield of 1 mg/l. The genome size of Micromonospora sp. strain M42 was estimated at 6.7 Mb by pulsed field gel electrophoresis. The biosynthetic gene pathway encoding manzamine A was investigated using both biochemistry and molecular methods yet it remains elusive. Micromonospora sp. strain M42 underwent UV mutagenesis leading to isolation of mutants with yield of manzamine A improved by 3.5 fold. One of the mutants produces manzamine B, the putative biosynthetic precursor of manzamine A. A fosmid library of Micromonospora sp. strain M42 was constructed and low-pass genome sequencing gave insights into the strain's genome and revealed a high number of genes devoted to the production of secondary metabolites including polyketides and non-ribosomal peptides. The isolation of Micromonospora sp. strain M42 greatly improves the chances of manzamines becoming a drug class for treatment of malaria

Characterization of a Culturable Alphaproteobacterial Symbiont Common to Many Marine Sponges and Evidence for Vertical Transmission via Sponge Larvae

A closely related group of alphaproteobacteria were found to be present in seven genera of marine sponges from several locations and were shown to be transferred between sponge generations through the larvae in one of these sponges. Isolates of the alphaproteobacterium were cultured from the sponges Axinella corrugata, Mycale laxissima, Monanchora unguifera, and Niphates digitalis from Key Largo, Florida; Didiscus oxeata and Monanchora unguifera from Discovery Bay, Jamaica; an Acanthostronglyophora sp. from Manado, Indonesia; and Microciona prolifera from the Cheasapeake Bay in Maryland. Isolates were very similar to each other on the basis of 16S rRNA gene sequence (>99% identity) and are closely related to Pseudovibrio denitrificans. The bacterium was never isolated from surrounding water samples and was cultured from larvae of M. laxissima, indicating that it is a vertically transmitted symbiont in this sponge. Denaturing gradient gel electrophoresis, 16S rRNA gene clone library analysis, and fluorescent in situ hybridization with probes specific to the alphaproteobacterium confirmed the presence of this bacterium in the M. laxissima larvae. The alphaproteobacterium was densely associated with the larvae rather than being evenly distributed throughout the mesohyl. This is the first report of the successful culture of a bacterial symbiont of a sponge that is transferred through the gametes

Microhabitats within Venomous Cone Snails Contain Diverse Actinobacteria▿ †

Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery

An analysis of the sponge Acanthostrongylophora igens’ microbiome yields an actinomycete that produces the natural product manzamine A

Sponges have generated significant interest as a source of bioactive and elaborate secondary metabolites that hold promise for the development of novel therapeutics for the control of an array of human diseases. However, research and development of marine natural products can often be hampered by the difficulty associated with obtaining a stable and sustainable production source. Herein we report the first successful characterization and utilization of the microbiome of a marine invertebrate to identify a sustainable production source for an important natural product scaffold. Through molecular-microbial community analysis, optimization of fermentation conditions and MALDI-MS imaging, we provide the first report of a sponge-associated bacterium (Micromonospora sp.) that produces the manzamine class of antimalarials from the Indo-Pacific sponge Acanthostrongylophora ingens (Thiele, 1899) (Class Demospongiae, Order Haplosclerida, Family Petrosiidae). These findings suggest that a general strategy of analysis of the macroorganism's microbiome could significantly transform the field of natural products drug discovery by gaining access to not only novel drug leads, but the potential for sustainable production sources and biosynthetic genes at the same time.ISSN:2296-774

ÉCRITURES EN LIGNE: PRATIQUES ET COMMUNAUTÉS. Sous la dir de Brigitte Chapelain. (485 p.)

"La communication écrite est encore jeune" écrivait R.Escarpit1 en 1973 ajoutant que celle-ci vieillissait moins vite que d'autres moyens de communication. Nous ne pouvons aujourd'hui que constater la pertinence de cette réflexion . En effet les formes de communication médiatisée par les technologies du numérique et des réseaux proposent une palette d'outils complémentaires d'écriture et de lecture, d'annotation, et d'édition personnelles et collectives qui ont développé le traitement de texte, l'écriture hypertextuelle, les mails , les chats , et des sites web comme les wikis. Ces dernières années Internet et son double pouvoir "numérique et connectique"2s'est révélé, comme ce fut le cas du livre, être un dispositif scripturaire, "qui condense et organise, qui schématise et appauvrit parfois"3, revalorisant le rôle informationnel et cognitif de l'écriture dont le développement relève de nombreux domaines culturels, éducatifs et professionnels. Le phénomène blog est sans doute l'exemple4 le plus récent de ces outils d'écriture. Les blogs sont notamment utilisés dans des applications littéraires, pédagogiques et entrepreneuriales donnant à l'écriture en ligne des nouveaux outils moins contraignants et plus maniables. Un colloque organisé à l'université de Rennes 2, en Septembre 2002, a engagé une réflexion pluridisciplinaire sur les dispositifs d'écriture en ligne et les pratiques communautaires émergentes. La littérature, l'éducation et l'organisation qui ne sont que rarement réunies ont retenu particulièrement notre attention. Le carrefour disciplinaire que constituent les sciences de l'information et de la communication permet de mettre à l'épreuve cette problématique commune que représente l'écriture en ligne en s'appuyant sur ces trois champs. Nous avons choisi d'en traiter deux dimensions essentielles :la dimension processuelle et la dimension organisationnelle. C'est ainsi qu'ont émergé les deux thèmes retenus du colloque: les pratiques et les communautés de l'écriture en ligne. La dimension processuelle porte sur les processus de production de ces écritures: les textes produits, les modes éditoriaux qui leur sont associés, les rôles de l'auteur et du lecteur, les genres d'écrits. La dimension organisationnelle s'inscrit dans les structures de travail et de création, la gestion des personnes et des savoirs,et les modes de développement et de circulation des productions d'écriture. Les travaux du colloque ont tenté de répondre à deux grandes interrogations portant sur ces dimensions. En quoi les pratiques d'écriture en ligne proposent-elles des procédures de travail et de création et des modèles de communication qui témoignent d'une réelle spécificité processuelle? Quelles formes organisationnelles et managériales caractérisent ces pratiques d'écriture? Comment les définir? Peut-on parler de communautés