养殖长茎葡萄蕨藻黑褐病的病原学研究

Etiology of black-brown disease in cultured Caulerpa lentillifera

中文关键词: 长茎葡萄蕨藻  黑褐病  溶藻弧菌

英文关键词: Caulerpa lentillifera  Black-brown disease  Vibrio alginolyticus

中文摘要:

      本研究从大连某养殖场发生黑褐病的长茎葡萄蕨藻(Caulerpa lentillifera)分离得到1株优势菌株CL2017070801002。采用该菌株浓度为103~108 CFU/ml的菌液浸泡感染长茎葡萄蕨藻，在7 d内，每个感染实验组的藻体都出现了不同程度的黑褐色典型发病症状，人工感染实验结果表明，CL2017070801002对长茎葡萄蕨藻有致病性。扫描电镜观察发现，藻体细胞壁表面聚集大量细菌，随着侵染时间加长，细胞组织破裂死亡。研究表明，CL2017070801002为本次发现的长茎葡萄蕨藻黑褐病的病原。结合革兰氏染色、生理生化特征和16S rDNA序列进化树分析结果，将该菌株鉴定为溶藻弧菌(Vibrio alginolyticus)。药敏实验结果显示，该菌株对氯霉素、四环素、氟罗沙星、强力霉素和氟苯尼考等药物高度敏感，对庆大霉素、克拉霉素等药物中度敏感，对青霉素、头孢氨苄、头孢拉定等药物不敏感。本研究为长茎葡萄蕨藻的细菌性病害防治提供了有益参考。

英文摘要:

      Caulerpa lentillifera is a seaweed species with increasing large-scale economic value due to its nutritional and health benefits. With the expansion of farming scale, problems associated with various diseases are becoming more common and severe. However, few research focusing on this topic have been published. In this study, the strain CL2017070801002 was isolated from C. lentillifera, which was diagnosed with black-brown disease in Dalian´s breeding farm. Following infection of healthy C. lentillifera with this strain at a concentration of 103~108 CFU/ml, each experimental group developed different black-brown lesions within 7 days. Under scanning electron microscopy, a large number of bacteria were accumulated on the cell surface of the alga, and the cells ruptured and died over time. These results indicated that CL201707070801002 was the causative pathogen of black-brown disease of C. lentillifera. Using gram staining as well as physiological and biochemical characteristics based on a 16S rDNA phylogenetic tree, the strain was identified as Vibrio alginolyticus. CL2017070801002 was highly sensitive to chloramphenicol, tetracycline, fleroxacin, doxycycline, and florfenicol; moderately sensitive to gentamicin and clarithromycin; and not sensitive to penicillin and cephalosporin. These results will provide useful information for the prevention and control of bacterial diseases of C. lentillifera.