Sterol profile of Neobenedenia melleni, a marine ectoparasite fish.

Neobenedenia melleni, a marine fish ectoparasite, is responsible for considerable losses in the mariculture industry. In maintaining the parasite's homeostasis, sterols are structural and functional lipids that perform vital functions. Thus, understanding the mechanisms of biosynthesis and the uptake of sterols can reveal potential pharmacological targets. The objective of this work was thereby to characterize the N. melleni sterols. The most abundant sterol found was cholesterol in either its free (47.48 ± 15.93 %) or esterified form. However, its precursors, squalene (3.53 ± 0.92 %) and desmosterol (0.25 ± 0.03 %), were also found, suggesting the uptake of these intermediates from hosts or an unusual active pathway of sterol biosynthesis, which can be further explored as pharmacological targets.

Bioremediation with freshwater bivalves: A sustainable approach to reducing the environmental impact of inland trout farms.

Integrated multi trophic aquaculture (IMTA) is well developed in seawater, while the only suitable organisms for bioremediation in freshwater are bivalves. The aim of this research has been to investigate a novel system, based on freshwater bivalves integrated with rainbow trout, for the bioremediation of inland aquaculture systems. The Unionid species selected for the experiments was Sinanodonta woodiana. Five mesocosm experiments were conducted to evaluate the efficiency of mussels in filtering the total bacteria and Aeromonas hydrophila, as well as their clearance efficiency on trout farm wastewater. The temperatures, dissolved oxygen, nitrates, and phosphates were monitored and were all within the physiological tolerance range of the species in all the experiments. The feasibility of bioremediation with S. woodiana in trout farming has thus been demonstrated, and among the tested rearing densities (3.75; 7.5; 15; 30 and 60 kg m-3) that of 7.5 kg m-3 was found to be optimal. The net reduction of the total bacterial concentration was as much as 72%, while that of A. hydrophila reached a level of 95-98%. No relevant effects of the mussels on particulate suspended material or sedimented material was observed, regardless of the temperature. The efficiency of freshwater bivalves in reducing the bacterial load, in particular toward A. hydrophila, indicates a bioremediation system with the possibility of interesting applications on inland fish farms, and as a biotechnological tool against the diffusion of antibiotic resistance in aquaculture.