摘要详情
1384 / 2024-09-26 11:37:57
Characterization of a new pathogenic isolate of Acinetobacter ursingii from the white shrimp Litopenaeus vannamei
Litopenaeus vannamei, Oryzias melastigma, Acinetobacter ursingii 31C2, pathogenicity, drug sensitivity, antimicrobial peptide
摘要待审
Body surface ulcers and visceral organ lesions are prevalent symptoms of several common diseases in Litopenaeus vannamei aquaculture, such as acute hepatopancreatic necrosis disease (AHPND), shell ulceration, and red leg disease, which are usually associated with bacterial infections and can lead to significant economic losses. However, the diversity and complexity of the pathogens pose challenges in the diagnosis and treatment of shrimp diseases. In November 2021, a shrimp farm located in Zhang Pu County, Fujian Province, China, reported an increased mortality rate among white shrimp. Concurrently, cutaneous ulcers and visceral organ lesions were observed in the affected individuals. In order to elucidate the etiology of cutaneous ulcers and visceral organ lesions in L. vannamei, pathogenic bacteria isolation and characterization was performed in this study. A total of 291 bacterial strains were successfully isolated and purified from different tissues of the diseased shrimp, including the heart, gills, stomach, intestines, hepatopancreas, eyes, and muscles, using BHI medium. Blood agar plate results showed that 55 strains of the bacteria exhibited β-hemolysis. These 55 hemolytic bacteria were found to be homologous to 24 species of bacteria by 16S rDNA sequencing, of which Acinetobacter ursingii 31C2 was found for the first time in L. vannamei. Infection of A. ursingii 31C2 in L. vannamei resulted in reddening of the caudal fin, partial necrosis and lysis of the hepatopancreas, and easy rupture of the intestines. After infection, Oryzias melastigma moved slowly, had swollen gills, and increased mortality. The results showed that A. ursingii 31C2 was pathogenic to both L. vanname and O. melastigma, and the 96-hour median lethal doses (LD50) was 2.83×104 CFU/g shrimp body weight and 2.58×106 CFU/fish, respectively. The drug sensitivity test results showed that A. ursingii 31C2 was susceptible to rifampicin, imipenem, levofloxacin, and gentamicin, but resistant to tetracycline, azithromycin, benzylpenicillin, piperacillin, and compound sulfamethoxazole. Two novel antimicrobial peptides identified in our laboratory showed strong antibacterial activity against A. ursingii 31C2, with minimum inhibitory concentrations (MIC) of 24 µg/mL (12.9 µM) and 6 µg/mL (2.76 µM), respectively. Taken together, this study provides important reference for the diagnosis and treatment of diseases caused by A. ursingii in L. vannamei. The role of antimicrobial peptides as a potential aquaculture antibacterial agent in the resistance of L. vannamei to infection will be further evaluated.
重要日期
-
会议日期
01月14日
2025
至01月17日
2025
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09月27日 2024
初稿截稿日期
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12月14日 2024
注册截止日期
主办单位
State Key Laboratory of Marine Environmental Science, Xiamen University
联系方式
- JKejing GU
- xm******@xmu.edu.cn
- +86*********
