Carvacrol, a phenolic monoterpenoid present in oregano and thyme essential oils and approved for use in human and animal food, was evaluated in a gnotobiotic Artemia brine shrimp model for dual protection against Vibrio campbellii. In vivo, carvacrol at effective, low-toxicity concentrations enhanced Artemia survival during V.
campbellii challenge. The protective effect correlated with reduced bacterial virulence, evidenced by diminished biofilm formation and lower hemolytic and caseinase activities.
Host responses were also affected: expression of defense-related genes—hsp70, prophenoloxidase, transglutaminase, and ferritin—exhibited time-dependent and stochastic modulation rather than sustained upregulation, suggesting altered, not simply amplified, immune signaling. These observations indicate that carvacrol may confer disease resistance through both pathogen-directed and host-directed mechanisms, with favorable safety in the tested context.
The findings support the translational potential of carvacrol as a food-grade antimicrobial strategy to aid disease control and health management in aquaculture. Uncertainty remains regarding performance under realistic farming conditions and the full balance of antimicrobial effects across diverse host–pathogen–environment scenarios.
campbellii challenge improved Artemia survival and exhibited low toxicity at concentrations effective for protection.