Comparative antibacterial activity of Cymbopogon citratus and Cymbopogon winterianus essential oils against Vibrio parahaemolyticus in shrimp aquaculture

Pathogenic microorganisms, particularly antibiotic-resistant bacteria, have emerged as major constraints to the pro- duction and commercialization of the Pacific white shrimp (Penaeus vannamei). This study aimed to evaluate the chemical composition, antibacterial activity, and potential synergistic effects of the essential oils from Cymbopogon citratus and C. winterianus collected in Brazil against Vibrio parahaemolyticus strains associated with shrimp aquaculture. The essential oils were obtained by hydrodistillation and characterized by GC–MS and GC-FID. Antibacterial activity was assessed against V. parahaemolyticus (IOC 18950) and a strain isolated from the hemolymph of farmed shrimp, with ampicillin, enrofloxacin, and oxytetracycline included as standard antibiotics for comparison. Major constituents were geranial (42.81%) and neral (33.37%) in C. citratus, and citronellal (38.86%) and geraniol (33.11%) in C. winterianus. MIC and MBC ranged from 0.156 to 0.313 mg/mL. C. citratus essential oil exhibited the strongest activity, especially against IOC 18950. No synergism was observed between essential oil combinations. Notably, C. winterianus essential oil demonstrated higher bactericidal efficacy than ampicillin. These essential oils are promising natural agents for controlling pathogenic Vibrio in aquaculture systems, highlighting their potential importance for tropical animal health and aquaculture production.