关键词: 虹鳟, 腐败希瓦氏菌, 16S rDNA, 药敏试验, 人工回归感染试验

Abstract: To clarify the pathogenic characteristics of bacterial diseases in a rainbow trout farm in Gansu Province and provide scientific basis for their prevention and control，a dominant strain SP001 was isolated from the viscera of the diseased rainbow trout. Comprehensive studies were conducted by morphological observation，Gram staining，biochemical identification，16S rDNA sequencing and phylogenetic analysis，virulence gene detection，growth characteristics determination，antibiotic sensitivity test，artificial regression infection assay and histopathological analysis. The results showed that the strain SP001 was a Gram‑negative rod‑shape bacterium，and its 16S rDNA sequence was 99.86% similar to that of Shewanella putrefaciens strain Sh1. Phylogenetic analysis further confirmed its taxonomic status. It carried dksA and fur virulence genes. The growth characteristics showed stable proliferation at both the optimal rainbow trout water temperature（18℃）and the higher temperature of 28 ℃ .It was sensitive to quinolones and some aminoglycoside antibiotics，and resistant to most β‑lactams. The cumulative mortality rate of artificial infection test for 7 days was 80%.The diseased fish showed characteristic lesions such as hemorrhage of fin base，necrosis of gill tissue，hepatosplenomegaly，which was consistent with the natural symptoms. In summary，the pathogen of rainbow trout disease in the farm is Shewanella putrefaciens，and the findings from this study provide an important theoretical basis for the diagnosis and prevention of the disease.

Key words: Rainbow trout, Shewanella putrefaciens, 16S rDNA, Antibiotic sensitivity test, Artificial regression infection assay