Dynamics of the Bacterial Cold-water Disease Pathogen, Flavobacterium psychrophilum, in Infected Fish Organs and Rearing Water after Warmed Water Treatment

作者：Sugahara Kazuhiro^*; Fujiwara Nagata Erina; Eguchi Mitsuru

来源：Fish Pathology, 2010, 45(2): 58-65.

DOI：10.3147/jsfp.45.58

• warmed water treatment
• Flavobacterium psychrophilum
• bacterial cold-water disease
• Plecoglossus altivelis

Bacterial cold-water disease (BCWD) causes heavy mortality of ayu Plecoglossus altivelis in Japan. To control BCWD of ayu, warmed water treatment at 28 degrees C has been used. However, the mechanism of this treatment is unknown. Hence, we investigated the growth/survival of Flavobacterium psychrophilum at 15-28 degrees C under two nutritional conditions: in modified cytophaga (MCY) broth and sterilized underground water. Within 2 days at 28 C in both the conditions, F psychrophilum totally lost its colony-forming ability. We also studied distributions of F psychrophilum in infected fish organs and in rearing water after various treatments. For bacteria detection, the colony-counting method and loop-mediated isothermal amplification (LAMP) method were used. For warmed water treatment, the rearing water was warmed from 18 degrees C to 23 degrees C or 28 degrees C for 3 days. The treatments were started 1 day after immersion infection. In the experimentally infected fish, F psychrophilum was detected neither in any fish organs nor in the rearing water after the 28 degrees C treatment for 3 days. These results indicate the effectiveness of the warmed water treatment at 28 degrees C against BCWD of ayu.

• 出版日期2010-6