Journal of Dalian Ocean University  2023, Vol. 38 Issue (6): 987-993 DOI: 10.16535/j.cnki.dlhyxb.2023-092 |
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| Isolation,identification and drug sensitivity of Pseudomonas veronii from diseased half smooth tongue-sole (Cynoglossus semilaevis Günther) |
| LIN Baozhu，ZHAO Lu，WANG Haoyi，HAN Zhuoran，SUN Jingfeng*
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Tianjin Key Laboratory of Aqua-ecology and Aquaculture，College of Fisheries，Tianjin Agricultural University，Tianjin 300384，China
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Abstract In order to investigate the pathogenesis of diseased half smooth tongue-sole (Cynoglossus semilaevis Günther), a bacterial strain was isolated from the liver of the diseased half smooth tongue-sole with body weight of 20 to 40 g, designed as CLPV-114, and identified by morphological observation, physiological, and biochemical features and the sequence analysis of 16S rRNA. The drug sensitivity, artificial infection, histopathological examination and determination of growth curve were examined in the strain CLPV-114. The median lethal dose was determined and histopathological observations were conducted in the artificial infection test. The results showed that the strain CLPV-114 was gram-negative bacterium, and closely related to Pseudomonas veronii (AF064460) and Pseudomonas veronii (AY144583), so identified as Pseudomonas veronii. The drug sensitivity test showed that CLPV-114 was highly sensitive to 18 kinds of drugs including amoxicillin, ampicillin, cefoperazone, moderately sensitive to 11 antibiotics such as nitrofurantoin, azithromycin, tetracycline, and resistant to antibiotics such as cefixime, sulfafurazole and sulfamethoxydiazine. Infection test showed that the clinical symptoms were similar to those of naturally diseased fish, with the LD50 of 1.3×107 CFU/mL in CLPV-114 against half smooth tongue-sole. Histopathological observations found that CLPV-114 strain caused obvious histological damage, such as hepatocellular tissue necrosis, vascular congestion of the central filament vessel of gill, haemorrhage and deposition of hemosiderin in the spleen, and the shedding of the intestinal villi. The finding indicates that the strain CLPV-114 isolated from the liver of diseased tongue sole is Pseudomonas veronii, which has strong pathogenicity to tongue sole and can cause significant pathological changes in different tissues, and provides an effective scientific reference for control of Pseudomonas veronii disease in half smooth tongue-sole.
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Published: 18 January 2024
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