嗜水气单胞菌不同分离株生化特性及胞外蛋白酶的检测

Detection of biochemical characters and extracellular proteases in the different isolates of Aeromonas hydrophila

嗜水气单胞菌可引起多种宿主患病,该菌致病性与其产生的多种毒力因子特别是胞外蛋白酶有关。本研究检测了26株嗜水气单胞菌不同分离株的生化指标,采用脱脂乳平板法检测了胞外蛋白酶的产生情况,并利用PCR技术检测了2种胞外蛋白酶基因ahp-A(编码丝氨酸胞外蛋白酶)和eprCAI(编码温敏胞外蛋白酶)。结果表明,大部分菌株生化指标表现为蔗糖(+)、阿拉伯糖(+)、葡萄糖(+)、甘露醇(+)、鸟氨酸脱羧酶(-)、肌醇(-)、七叶苷(+);脱脂乳平板法检测发现,91.7%(22/24)的致病菌株均能产生胞外蛋白酶,而2株无毒株则不能产生,对2个胞外蛋白酶基因的检测也得到相似的结果。本研究将为嗜水气单胞菌的流行病学调查和致病机制的深入研究奠定基础。

Aeromonas hydrophila is a pathogen that causes disease in a wide range of hosts due to its multifactorial virulence, especially extracellular proteases. Biochemical characters were detected in 27 A. hydrophila isolates. The activity of extracellular proteases was analyzed by patching bacteria on LA plates supplemented with 1% skim milk. The two genes, ahp-A encoding serine extracellular protease and eprCAl encoding temperature-labile extracellular protease, were detected by PCR in the isolates. The results showed that most of isolates could dissolve sucrose, arabinose glucose, mannitol and esculin, but ornaline and inositol could not be utilized in the bacterial strains. The analysis of exoenzyme activities revealed that 91.7% of virulent strains had a high level of exoenzyme activities, while the two avlrulent strains could not produce the detectable exoproteases. The detection for the two exoprotease genes showed a similar result. The present work will apply a good foundation for a better understanding of epldemlologlcal investigation and virulence mechanisms of A. hydrophila.