关键词: 水貂, 肺炎克雷伯菌, 分离鉴定, 胞外分泌蛋白, 核酸酶

Abstract: In order to identify the pathogens causing mink pneumonia,a suspected strain of Klebsiella pneumoniae was isolated from clinical death cases.The nuclease activity of extracellular protein of Klebsiella pneumoniae was detected by agarose gel electrophoresis, and the effects of temperature, pH value and metal ions on the activity of nuclease were investigated. The results showed that Klebsiella pneumoniae was identified by microscopic examination and PCR.The exocrine protein of Klebsiella pneumoniae showed the activity of nuclease for degradation of λDNA.The optimal temperature range was 30—37 ℃ ,and the optimum pH value was 7.0.The activity of nuclease was weak under high temperature and alkaline conditions.Univalent metal ions (Na⁺and K⁺) and some divalent metal ions (Ca²⁺,Ba²⁺,Ni²⁺,Zn²⁺and Cu²⁺) had no significant effect on the nuclease activity of extracellular secretory protein of Klebsiella pneumoniae.The 5.00—10.00 mmol/L Co²⁺and Fe³⁺and 10. 00 mmol/L Mg²⁺and Mn²⁺could promote the activity of extracellular nuclease cleavaging λDNA.In this study,a Klebsiella pneumoniae strain was isolated from clinical mink pneumonia,and its exocrine protein had nuclease activity.

Key words: Mink, Klebsiella pneumoniae, Isolation and identification, Extracellular secretory protein, Nuclease