Impact of co-culture on the metabolism of marine microorganisms

Natural products from plants have been listed for hundreds of years as a source of biologically active molecules. In recent years, the marine environment has demonstrated its ability to provide new structural entities. More than 70% of our planet’s surface is covered by oceans, and with the technical advances in diving and remotely operated vehicles, it is becoming easier to collect samples. Although the risk of rediscovery is significant, the discovery of silent gene clusters and innovative analytical techniques has renewed interest in natural product research. Different strategies have been proposed to activate these silent genes, including co-culture, or mixed fermentation, a cultivation-based approach. This review highlights the potential of co-culture of marine microorganisms to induce the production of new metabolites as well as to increase the yields of respective target metabolites with pharmacological potential, and moreover to indirectly improve the biological activity of a crude extract

Anguilla sp. Diseases Diagnoses and Treatments: the Ideal Methods at the Cross Roads of Conservation and Aquaculture Purposes

International audienceAnguilla anguilla, A. japonica and A. rostrata are the most fished and consumed eel species. However, these species are Critically Endangered, Endangered and Endangered respectively. A combination of factors is thought to be responsible for their decline including fisheries, climate change, habitat destruction, barriers to migration, pollution and pathogens. Among them, viruses, bacteria and parasites are causing weakening of wild eels and serious economic losses for fishermen and eel farmers. Early detection of pathogens is essential to provide appropriate responses both for conservation reasons and to limit economic losses. Classic diagnosis approaches are time consuming and invasive and usual treatments e.g. antipathogenic substances are becoming obsolete because of pathogen resistance and environmental impact problems. The need for early and noninvasive diagnostic methods as well as effective and environmentally friendly treatments has increased. Vaccine development and diet supplementation have known a growing interest since their use could allow prevention of diseases. In this review, we summarize the main pathogens-viruses, bacteria and parasites-of the three northern temperate eel species, the methods used to detect these pathogens, and the different treatments used. We discussed and highlighted the need for non-invasive, rapid and efficient detection methods, as well as effective and environmentally friendly treatments for both conservation and aquaculture purposes

Use of Medicinal Plants in Aquaculture

Plants have been reported to produce various effects such as antistress, growth promotion, appetite stimulation, immunostimulation, aphrodisiac and to have antipathogen properties in fish and shrimp aquaculture due to their varied active principles such as alkaloids, terpenoids, tannins, saponins and flavonoids. To date, most scientific studies on the use of medicinal plants in aquaculture have focused on identification of biological activity rather than natural product determination. The plant species that have displayed the highest potential for use in aquaculture are garlic (Allium sativum), pomegranate (Punica granatum), bermuda grass (Cynodon dactylon), Indian ginseng (Whitania somnifera) and ginger (Zingiber officinale). Algae are considered to be a rich source of original bioactive molecules which display multiple bioactivities. In aquaculture, several recent studies have showed the potential of algae for the treatment of pathogens or to improve fish fitness

Biological and Ecological Roles of External Fish Mucus: A Review

International audienceFish mucus layers are the main surface of exchange between fish and the environment, and they possess important biological and ecological functions. Fish mucus research is increasing rapidly, along with the development of high-throughput techniques, which allow the simultaneous study of numerous genes and molecules, enabling a deeper understanding of the fish mucus composition and its functions. Fish mucus plays a major role against fish infections, and research has mostly focused on the study of fish mucus bioactive molecules (e.g., antimicrobial peptides and immune-related molecules) and associated microbiota due to their potential in aquaculture and human medicine. However, external fish mucus surfaces also play important roles in social relationships between conspecifics (fish shoaling, spawning synchronisation, suitable habitat finding, or alarm signals) and in interspecific interactions such as prey-predator relationships, parasite-host interactions, and symbiosis. This article reviews the biological and ecological roles of external (gills and skin) fish mucus, discussing its importance in fish protection against pathogens and in intra and interspecific interactions. We also discuss the advances that "omics" sciences are bringing into the fish mucus research and their importance in studying the fish mucus composition and functions

Metabolomics and Marine Biotechnology: Coupling Metabolite Profiling and Organism Biology for the Discovery of New Compounds

International audienceThe high diversity of marine natural products represents promising opportunities for drug discovery, an important area in marine biotechnology. Within this context, high-throughput techniques such as metabolomics are extremely useful in unveiling unexplored chemical diversity at much faster rates than classical bioassay-guided approaches. Metabolomics approaches enable studying large sets of metabolites, even if they are produced at low concentrations. Although, metabolite identification remains the main metabolomics bottleneck, bioinformatic tools such as molecular networks can lead to the annotation of unknown metabolites and discovery of new compounds. A metabolomic approach in drug discovery has two major advantages: it enables analyses of multiple samples, allowing fast dereplication of already known compounds and provides a unique opportunity to relate metabolite profiles to organisms’ biology. Understanding the ecological and biological factors behind a certain metabolite production can be extremely useful in enhancing compound yields, optimizing compound extraction or in selecting bioactive compounds. Metazoan-associated microbiota are often responsible for metabolite synthesis, however, classical approaches only allow studying metabolites produced from cultivatable microbiota, which often differ from the compounds produced within the host. Therefore, coupling holobiome metabolomics with microbiome analysis can bring new insights to the role of microbiota in compound production. The ultimate potential of metabolomics is its coupling with other “omics” (i.e., transcriptomics and metagenomics). Although, such approaches are still challenging, especially in non-model species where genomes have not been annotated, this innovative approach is extremely valuable in elucidating gene clusters associated with biosynthetic pathways and will certainly become increasingly important in marine drug discovery

The link between external microbiota and monogenean ectoparasites in Sparids (Teleostei)

peer reviewe

Antifouling Activity of Meroterpenes Isolated from the Ascidian Aplidium aff. densum

International audienc

Antibacterial Activities and Life Cycle Stages of <i>Asparagopsis armata</i>: Implications of the Metabolome and Microbiome

The red alga Asparagopsis armata is a species with a haplodiplophasic life cycle alternating between morphologically distinct stages. The species is known for its various biological activities linked to the production of halogenated compounds, which are described as having several roles for the algae such as the control of epiphytic bacterial communities. Several studies have reported differences in targeted halogenated compounds (using gas chromatography–mass spectrometry analysis (GC-MS)) and antibacterial activities between the tetrasporophyte and the gametophyte stages. To enlarge this picture, we analysed the metabolome (using liquid chromatography–mass spectrometry (LC-MS)), the antibacterial activity and the bacterial communities associated with several stages of the life cycle of A. armata: gametophytes, tetrasporophytes and female gametophytes with developed cystocarps. Our results revealed that the relative abundance of several halogenated molecules including dibromoacetic acid and some more halogenated molecules fluctuated depending on the different stages of the algae. The antibacterial activity of the tetrasporophyte extract was significantly higher than that of the extracts of the other two stages. Several highly halogenated compounds, which discriminate algal stages, were identified as candidate molecules responsible for the observed variation in antibacterial activity. The tetrasporophyte also harboured a significantly higher specific bacterial diversity, which is associated with a different bacterial community composition than the other two stages. This study provides elements that could help in understanding the processes that take place throughout the life cycle of A. armata with different potential energy investments between the development of reproductive elements, the production of halogenated molecules and the dynamics of bacterial communities

Development of a multiblock metabolomics approach to explore metabolite variations of two algae of the genus Asparagopsis linked to interspecies and temporal factors

International audienceMetabolomics, the science that describes a full range of small molecules in a sample at a time point, is a powerful tool to evaluate patterns in metabolite variations affected by environmental factors. We developed a multiblock metabolomics approach using LC-HRMS, HS-SPME-GC–MS and 1H NMR to study the interspecies and temporal metabolites variations of two red algae species from the genus Asparagopsis well-known for their broad range of biological activities. Samples were collected over two years at 5 sites. For each sample, a biphasic extraction was performed to allow distinct analyses of apolar phases by LC-HRMS and of polar phases by 1H NMR. The remaining lyophilized algal powder was analysed using a HS-SPME-GC–MS method. Temporal variation of antibacterial activities of extracts of the two algae was also studied and its potential covariation with algal metabolome was evaluated. On the one hand, the multiblock analysis allowed the interspecies and temporal discrimination of the two species, and putative identification of potential chemotaxonomic markers including highly halogenated molecules. Organosulfur compounds enriched in A. armata samples could be detected with both 1H NMR (taurine and isethionic acid) and LC-HRMS (sulfolipids). On the other hand, the variation in several metabolites intensities could be related to temporal effects, probably linked to environmental factors. It is the case of floridoside, a major carbohydrate, and citrulline (1H NMR) that both can have antioxidant properties, but also of various sulfolipids (LC-HRMS). The antibacterial activity of extracts of both species was constant throughout the year and did not covary with metabolome. This work is also the first to report the study of the metabolome of the two different species of the genus Asparagopsis by 1H NMR and HS-SPME-GC–MS

Effects of local Polynesian plants and algae on growth and expressionof two immune-related genes in orbicular batfish (Platax orbicularis)

International audienceThe emerging orbicular batfish (Platax orbicularis) aquaculture is the most important fish aquacultureindustry in French Polynesia. However, bacterial infections are causing severe mortality episodes.Therefore, there is an urgent need to find an effective management solution. Besides the supplyingdifficulty and high costs of veterinary drugs in French Polynesia, batfish aquaculture takes place close tothe coral reef, where use of synthetic persistent drugs should be restricted. Medicinal plants andbioactive algae are emerging as a cheaper and more sustainable alternative to chemical drugs. We havestudied the effect of local Polynesian plants and the local opportunistic algae Asparagopsis taxiformis onbatfish when orally administered. Weight gain and expression of two immune-related genes (lysozyme ge Lys G and transforming growth factor beta - TGF-b1) were studied to analyze immunostimulant activityof plants on P. orbicularis. Results showed that several plants increased Lys G and TGF-b1 expressionon orbicular batfish after 2 and 3 weeks of oral administration. A. taxiformis was the plant displaying themost promising results, promoting a weight gain of 24% after 3 weeks of oral administration andsignificantly increasing the relative amount of both Lys G and TGF-b1 transcripts in kidney and spleen ofP. orbicularis