Relationship between in vitro Motility of Pseudomonas plecoglossicida and Clinical Conditions in Affected Ayu

Pseudomonas plecoglossicidaの運動性と病魚の腹水症状との関係

Park Se Chang

Nakai Toshihiro

Yuasa Akihiko

魚病研究

Fish Pathology

徳島県下で養殖アユから分離されたP. plecoglossicidaの殆どは、病魚における腹水症状の有無に関係なく非運動性株であった。運動性株を筋肉内接種後、死亡したアユからは運動性株しか分離されなかったが、非運動性株を接種したアユからは運動性、非運動性両タイプの株が分離された。これらの死亡魚の大半は腹水症状を呈した。また、長時間液体培養すると非運動性株が運動性株に変化した。以上のことから、病魚における腹水症状と分離株の運動性との間に一定の関係は無いと結論された。

This study was conducted to verify the previous contrasting results on the motility of Pseudomonas plecoglossicida and clinical conditions (bloody ascites) in affected ayu Plecoglossus altivelis. In the present field surveys at Tokushima Prefecture in 1999 and 2001, all P. plecoglossicida isolates from dead ayu, except one isolate from a fish with ascites, were non-motile irrespective of the presence of bloody ascites. When ayu were injected intramuscularly with non-motile strains, either motile or non-motile isolates were obtained from the kidney of dead fish, while only motile ones were isolated after injection of motile strains. Bloody ascites manifested in most of the affected fish after injection of either type of the bacterium. In in vitro broth culture conditions, the non-motile strains altered into motile ones during two-week incubation. These results indicate that there are no relationship between in vitro motility of P. plecoglossicida and the presence of bloody ascites in affected ayu, and that the phenotypic alteration in the motility of P. plecoglossicida occurs under both in vitro and in vivo conditions.

Pseudomonas plecoglossicida

bacterial motility

bacterial hemorrhagic ascites

Plecoglossus altivelis

ayu

Fishing industry. Fisheries [ 660 ]

eng

日本魚病学会

Copyright (c) 2002 The Japanese Society of Fish Pathology

[ISSN] 0388-788X

[NCID] AN00063165