Biotechnology for a Sustainable Aquaculture: Selection of Safe Marine Bacteria Producers of LC-PUFAs and Antimicrobials

The contribution of aquaculture to global food production in the fishing industry is expanding. The sustainability of the sector urge aquaculture industry to develop processes aimed at improving quantity and quality of fish, containing costs, reducing environmental threats by minimizing wastes and valorizing by-products. Several studies were carried out on the valorisation of fishing industry by-products/wastes and many of the products obtained are available in commerce. However, only very few reports are available on the selection/application of probiotics in aquaculture as well as on the use of antimicrobial compounds from microbial origin for the control of bacterial pathogens. In this context, the aim of the research activity is to select novel safe marine bacteria able to produce LC-PUFAs and/or antimicrobial compounds active against aquaculture fish pathogenic bacteria with the perspective of their application in aquaculture. The first part of the work has been dedicated to the selection of LC-PUFAs bacterial producers. For this purpose, 209 marine bacterial isolates from the Mediterranean Sea was screened in order to select new LC-PUFAs, EPA and DHA bacterial producers. After colourimetric screening, ITS typing, GC-FID analysis and molecular identification of marine isolates, different Marinobacter sp., Thalassospira sp and Halomonas sp. isolates could produce DHA. 41 isolates was screened for the production of antimicrobial compounds exhibiting activity against farmed fish pathogens. After screening and preliminary characterization, were selected 8 marine bacterial isolates able to produce stable compounds. In conclusion 10 strains able to produce both antimicrobial compounds active against different aquaculture fish pathogenic bacteria and LC-PUFAs were selected. These results are interesting and promising since these isolates belong to bacterial species that have never been reported to be involved in human or animal pathology and exhibited traits that give them high potential for the application in aquaculture in order to optimize fish production.