Potential of Chinese chive oil as a natural antimicrobial for controlling Flavobacterium columnare infection in Nile tilapia Oreochromis niloticus

Chinese chive Allium tuberosum oil was studied for its diallyl sulfide content and its antimicrobial activity against Flavobacterium columnare in fish both in vitro and. The oil was found to have a very low concentration of diallyl monosulfide relative to the other diallyl sulfides (diallyl disulfide, diallyl trisulfide, and diallyl tetrasulfide) identified. In the in vitro study, the Chinese chive oil had a bacteriocidal effect on all tested strains of F. columnare, with varied minimal inhibitory concentrations. The median lethal dose (LD(50)) of FC4 for Nile tilapia Oreochromis niloticus was determined to be 3.72 x 10(3) CFU/fish. In the in vivo trial, no mortality was observed in fish fed fish diets supplemented with 800 mg/kg Chinese chive oil and 100 mg/kg of oxytetracycline hydrochloride 5 days prior to infection with F. columnare strain 4 at a LD(50). These results indicate that Chinese chive oil has the potential to replace antibiotics for controlling fish disease caused by F. columnare.