Antibacterial Activity of Nanoemulsions Prepared with Essential and Seed Oils Against Isolated Bacteria from Rainbow Trout (Oncorhynchus mykiss)

This study investigated the inhibitory effect of nanoemulsions (NEs) derived from various essential oils (EOs) and seed oils (SOs) against pathogenic bacteria isolated from rainbow trout (Oncorhynchus mykiss). The EOs of eucalyptus, mandarin, and basil were extracted by hydrodistillation, while the SOs of avocado and pumpkin were extracted by supercritical fluids. GC–MS analysis determined the chemical composition, revealing that limonene (70.88%), eucalyptol (57.85%), and camphor (24.61%) were the main components of the EOs. The SOs were rich in palmitic acid (avocado) and linoleic acids (pumpkin) and contained phytosterols such as β-sitosterol and stigmasterol. Avocado seed oil had the highest total phenolic content and antioxidant activity. Eight stable NEs, prepared from individual and mixed oils, were tested against Salmonella enterica subsp. salamae, Escherichia coli, Klebsiella variicola, Bacillus oceanisediminis, and Bacillus thuringiensis. Most NEs were effective against E. coli and B. oceanisediminis, with an additive effect for SOs mixtures and a minimum inhibitory concentration of 0.53 μL/mL (E. coli), 0.53 μL/mL (B. oceanisediminis), and 2.13 μL/mL (B. thuringiensis). The bacteriostatic and bactericidal activity was 1.62 and 6 h with E. coli and NE Mix AP. These findings suggest that nanoemulsions containing SOs are promising candidates for controlling bacterial contamination in fishery products.