关键词: 大黄鱼, 变形假单胞菌, 16S rDNA, gyrB, large yellow croaker（Pseudosciaena crocea）, Pseudomonas plecoglossicida, 16S rDNA, gyrB

Abstract: The cultured large yellow croakers（Pseudosciaena crocea）of Luoyuan bay got white nodules disease at the end of spring and the beginning of summer in 2013. The pathogen was isolated from the fishes’ spleen, liver and kidney with significant pathological signs, then its morphological, physiological and biochemical characteristics, taxonomic status, and drug sensitivity were analyzed. The 16S rDNA sequences of the pathogen was more than 99% homology with Pseudomonas plecoglossicida in P.putida group, the analysis of housekeeping gene gyrB confirmed its phylogenetic affiliation and showed identities more than 99% homology, which was also demonstrated by biochemical tests. The test result of the sensitivity to antibiotics showed that doxycycline, norfloxacin and enrofloxacin had the most inhibitive effects on the strains, while ofloxacins, levofloxacin and tetracycline had intermediate sensitive.