坛紫菜叶状体的细菌性红烂病研究

Study on a bacterial red-rotting disease of Porphyra haitanensis (Bangiales, Rhodophyta)

本实验对发生在福建省平墰岛自然海区的野生坛紫菜(Porphyra haitanensis)叶状体上的红烂病进行了研究。患病叶状体上存在大小不等、肉眼可见的圆形或亚圆形病斑,镜检发现病斑内存在大量铁锈红色的死细胞和少量已解离的发绿或发白死细胞。将患病叶状体与健康坛紫菜叶状体共培养3d后,后者也出现了相同的红烂病,表明该病是由传染性病原侵入引起的。从患病叶状体中分离到一种病原菌,能感染健康叶状体使其出现相同的病症。该病原菌具有分泌毒素和微弱的消化琼胶能力,经高压灭菌或煮沸后的病原菌液,其杀死紫菜细胞的能力比未处理的病原菌液增加了数倍,这说明该菌可能通过释放内毒素来杀死叶状体细胞。鉴于此病是由于病原菌侵入叶状体并释放内毒素杀死紫菜细胞,且死亡细胞呈铁锈红色,故将其命名为"坛紫菜细菌性红烂病"。

A serious red-rotting disease was found on the gametophytic blades of wild Porphyra haitanensis collected from the coast of Pingtan Island in Fujian Province. In the foci of the diseased blades, most of the dead cells were reddish brown in color, some of which were isolated and became green or white in color. When the diseased blades were co-cultured with the healthy blades grown in the lab, the latter were infected and appeared the same symptoms after 3 days of culture. This result indicated that the disease was not caused by physiological and/or ecological factors. While the bacterium isolated from the diseased blades was inoculated on the healthy blades, the same symptoms appeared on the healthy blades after culture for 3 days. This result showed that the obtained bacterium was pathogen of the disease. The pathogen has weak ability to degrade agar of the solid medium and can secrete toxin to kill Porphyra cells. When the Porphyra blade was cultured in the sterilized or boiled culture of the pathogen, it was found that much more cells of the blades were killed than those cultured in the untreated culture of the pathogen, indicating that much more endotoxin was released after the cell walls of the bacteria were broken during sterilizing or boiling. This bacterial disease was named bacterial red-rotting disease of Porphyra blade for that the pathogen secretes endotoxin to kill the blade cells and the dead cells were reddish brown in color. [Journal of Fishery Science s of China, 2008, 15 （2） ： 313-322]