[Isolation and identification of the pathogenic strain of Vibrio harveyi from Miichthys miiuy]

An outbreak of disease on the cultured Miichthys miiuy occurred in Zhoushan of Zhejiang province. The symptom displayed as skin ulceration and the inside apparatus turned white.

We isolated a dominant bacterial strain from the diseased Miichthys and assigned it as strain 090212. The artificial infection test proved that the isolate 090212 was the pathogenic bacterium that caused the disease. We applied physiological and biochemical characterization and API system in the bacterial classification. In order to confirm the result, we amplified a 1458bp sequence of 090212' s 16S rDNA and compared with other Vibrio in GenBank.

The results turned out that 090212 was Gram negative and short rod with single polar flagellum. Homology analysis and phylogenetic study showed that strain 090212 had the highest similarity to Vibrio harveyi, with 99% identity. The sensitivity test of strain 090212 to 28 kinds of antibiotics revealed that the pathogen was sensitive to drugs such as Florfenicol and Tetracycline.

This paper revealed for the first time that the causative pathogen, Vibrio harveyi, lead to the mass mortality of Miichthys, which will be helpful in the disease control and health management during Miichthys cultivation.