Essential oils promote antibacterial and antiviral defense across species

Essential oils are naturally volatile substances produced by plants, presenting potential antibiotics and immunoprophylactics, being used as alternative additives in aquaculture. However, how to use different essential oils to promote the disease resistance abilities of aquatic teleosts, and what are the potential regulating mechanisms, are still scarce. In this study, we found that the combined essential oils -a mixture of cinnamaldehyde, thymol, carvacrol, and monolaurin, in a suitable ratio (10%:5%:10%:75%), were added in the basal diet at a 0.1% concentration, could effectively promote disease resistance of zebrafish (Danio rerio), grass carp (Ctenopharyngodon idella), and Chinese soft-shell turtles (Trionyx sinensis). Mechanistically, the combined essential oils promoted the transcriptional expression of anti-inflammatory factors, such as phagosome and antigen processing and presentation genes across species. Meanwhile, the combined essential oils promoted the AKT and ERK pathways to enhance the anti-inflammatory capacities of the teleosts and Chinese soft-shell turtles. These jointly contribute to the improved disease resistance to pathogen infections across species. These data reveal the potential of combined essential oils in promoting the disease resistance of aquatic species, and shed some light on developing green technologies in disease treatment in aquaculture.