The advancement of sustainable aquaculture necessitates innovative approaches to disease management, mainly through utilizing natural antimicrobial agents. These agents possess bioactive properties that can enhance animal health and welfare. Currently, the exploration of essential oils in aquaculture has focused on their roles as antioxidants, antimicrobials, antifungals, anesthetics, immunostimulants, and stress reducers, highlighting their potential as an alternative approach to developing sustainable aquaculture practices. Given their high volatility, low water solubility, and poor environmental stability, encapsulating essential oils has emerged as a promising strategy. This study introduces a novel approach utilizing nanostructured lipid carriers (NLCs) to encapsulate essential oils from Lippia origanoides Kunth (syn. Lippia sidoides ), a Brazilian aromatic plant known as pepper-rosemary. Its leaves contain an essential oil rich in substances of recognized antimicrobial properties, including thymol, carvacrol, and caryophyllene. The nanostructured lipid carriers, chosen for their biocompatibility and low toxicity, effectively might encapsulate L. sidoides essential oil. Our encapsulation technique employs a hot emulsification method using high-speed homogenization followed by ultrasonication, along with a selection of surfactants (poloxamer, quillaja saponins, and whey protein concentrate), aiming to enhance the oil’s solubility, stability, and efficacy against aquacultural pathogens such as Aeromonas veronii , Aeromonas caviae , and Aeromonas hydrophila isolated from fish. The bactericidal activity of the lipid formulations was assessed by measuring the minimum inhibitory concentration (MIC) and bactericidal concentrations (MBC) using the microdilution broth method, as recommended by the Clinical and Laboratory Standards Institute. The main results are presented in Table 1.
The developed lipid formulations were water-dispers ible, and their characteristics - mean particle size, polydispe rsity index, and zeta potential - were assessed, along with their pH and conductivity. The evaluation of the MIC and MBC of the nanostructured lipid carriers (NLCs ) formulations showed that they significantly inhibited the growth of pathogens. The choice of surfactant was found to influence antimicrobial efficacy. Remarkably, formulations incorporating quillaja saponins demonstrated increased effectiveness in specific assays, indicating their potential as a significant component in the antimicrobial delivery system.