Actividad antibacteriana de la hemolinfa de Penaeus vannamei tras la administración de un extracto de Oreganum vulgare

Abstract

CONDITION FOR PUBLICATION OF PROJECT. The culture of the shrimp Penaeus vannamei faces constant threats from infections by Vibrio spp., the causative agents of vibriosis, which generate high mortality and economic losses in the aquaculture sector. The indiscriminate use of antibiotics has promoted bacterial resistance and has had negative effects on the environment, making it necessary to evaluate sustainable alternatives. In this study, we determined the immunomodulatory capacity of aqueous extracts of Oreganum vulgare. As a preliminary step, the effective in vivo dose was determined. To this end, the antibacterial activity of O.vulgare extracts was determined at different concentrations in vitro (agar diffusion). The extracts were applied at different concentrations against three pathogenic vibrios, demonstrating inhibition zones depending on the dose, confirming a dose-dependent effect attributable to phenolic metabolites such as thymol and carvacrol. The extracts were also evaluated for their in vitro immunomodulatory effects (O2- y PO). This study included the standardization of an assay to evaluate the antibacterial capacity of shrimp hemolymph (plasma and hemocyte extracts) against the three pathogenic vibrio species. V. campbellii was found to be sensitive to the hemolymph, while V. parahaemolyticus was not. Field validation was subsequently performed on shrimp treated with oregano extracts and an untreated control group. Organisms exposed to oregano showed reduced phenoloxidase activation but not reduced superoxide anion generation. These shrimp also exhibited higher plasma protein concentrations and increased survival. Overall, the results confirmed the efficacy of oregano in immunomodulating P. vannamei. Further studies using bacterial strains with greater sensitivity to shrimp hemolymph are needed to complete the standardization of the antibacterial test.