Abstract: A dominant bacterium CSL1 was isolated from kidney of giant gouramiOsphronemasgoramywith exophthalmic disease, and artificial infection, morphological and physiological, and chemical experiments were carried out by intraperitoneal injection and immersion. The intraperitoneal injection of the bacterium(0.2 mL of bacterium,1×108cfu/mL) showed 66.7% mortality in the tested giant gourami, immersion of the injured fish with the bacterium(1×108cfu/mL) led to 100% mortality, and 0 mortality, and the same symptoms as the naturally infected giant gourami were found in the immersion of the fish with the bacterium(1×108cfu/mL). The bacterial morphology, physiology and biochemistry assays revealed that the isolated bacterium was preliminarily determined to beAeromonascaviae. The 16S rRNA gene was cloned, sequenced and analyzed in the bacterium by a molecular method. Blast and phylogenetic tree showed that 16S rRNA gene shared high similarity with its counterpart ofA.caviaefound in GenBank, indicating that the bacterium isolated was a strain ofA.caviae. The drug sensitivity test showed that the isolated bacterium was highly sensitive to eight kinds of antibiotics including levofloxacin, norfloxacin, enrofloxacin, ofloxacin, gentamycin, namycin, tobramycin, and pipemidic acid, intermediate sensitive to azithromycin,neomycina, and doxycycline, and resistant to eight kinds of antibiotics including novobiocin, nalidixin, ampicillin, penicillin, amoxicillin, trimethoprim, streptomycin，and sulfamethoxazole. The findings indicated that the pathogenic bacterium of exophthalmic disease in giant gourami wasA.caviae, and provided reference to preventing and curing the disease, gentamicin being a reference drug for treating the cultured fish related diseases caused byA.caviae.
2014, Vol. 29 
