Biosynthesis of long-chain polyunsaturated fatty acids in aquatic invertebrates: applications in aquaculture nutrition

Abstract

Aquatic invertebrates have some ability to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFA) including the so-called “omega-3” (or n-3) fatty acids. This paper briefly overviews the elongase and desaturase enzymes responsible for LC-PUFA biosynthesis in aquatic invertebrates. Moreover, the paper will focus on two potential applications that knowledge on the molecular mechanisms of LC-PUFA biosynthesis in aquatic invertebrates can have in aquaculture nutrition. First, the complement and functions of elongase and desaturase enzymes existing in the common octopus Octopus vulgaris has allowed the identification of the essential fatty acids (EFA) for this species. This methodological approach provides direct evidence of the enzymatic capacity existing in a particular species and thus is very useful to establish which fatty acids must be provided in the diet to ensure normal growth and survival. Second, the existence of complete enzymatic activities enabling the endogenous production of n-3 LC-PUFA in some aquatic invertebrates implies that their culture on low nutritional value (i.e. low n-3 LC-PUFA) materials including waste streams, can lead to the production of highly nutritious, n-3 rich meals for aquafeed. This paper will discuss the potential to explore this novel strategy in polychaetes, provided their enzymatic capacity for LC-PUFA biosynthesis, along other biological features.