Mediterranean Sea bacteria as a potential source of long-chain polyunsaturated fatty acids

Long-chain polyunsaturated fatty acids (LC-PUFAs), including EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are important nutritional ingredients in fish feed. So far, fish oil has been used as a main source of LC-PUFAs; however, the limited global supply of fish oil is not able to meet the demand of the growing aquaculture sector. Hence, sustainability of aquaculture industry could be supported by searching alternative sources of these compounds. Marine microorganisms represent a sustainable and stable supply source of LC-PUFAs. A collection of 209 bacterial isolates obtained from sediment samples recovered in the Mediterranean Sea was screened in order to select new LC-PUFAs producers. Among 95 putative producers selected based on colourimetric screening, 31 quickly growing were selected for further studies. The detection of LC-PUFAs was confirmed from 15 isolates belonging to the genera Marinobacter, Halomonas and Thalassospira by GC-FID analysis. Among them, the isolate Marinobacter sp. G16.20 was found to be a potentially high LC-PUFA producer exhibiting relatively high levels of DHA in particular (maximum productivity of 1.85 ± 0.371 mg/g, representing 45.89% of the total fatty acids detected and identified). Microorganisms belonging to the genera reported in this study showed biotechnological traits interesting for their potential future application in aquaculture.