温度对大黄鱼源变形假单胞菌胞外产物酶活力的影响

Effect of Temperature on the Enzyme Activity of Extracellular Products of Peseudomonas plecoglassicida Isolated from Larimichthys crocea

为了研究大黄鱼源变形假单胞菌胞外产物的致病性,在内脏白点病的高发温度（18℃）培养大黄鱼的病原菌——变形假单胞菌,利用玻璃纸覆盖平板技术制备其胞外产物,测定不同温度（低温不致病温度12℃、高发致病温度18℃和高温不致病温度28℃）下其胞外产物的酶活力.结果显示：变形假单胞菌胞外产物的淀粉酶、丝氨酸蛋白酶类、天冬氨酸蛋白酶类、类胃蛋白酶、类糜蛋白酶、卵磷脂酶、酸性磷酸酯酶和碱性磷酸酯酶的活性受温度影响比较大,28℃条件下酶活力显著（P〈0.05）高于12℃或者18℃时的酶活力;半胱氨酸蛋白酶类、氨肽酶的活性和溶血活性受温度影响没有显著性变化（P〉0.05）.实验结果表明,虽然变形假单胞菌胞外产物是其致病因素之一,但大黄鱼内脏白点病在特定温度（16~20℃）下高发并非是由于胞外产物在该温度下的活性较高.该结果增进了对大黄鱼内脏白点病发病机理的认识.

In order to study the pathogenicity of ECP from Peseudomonas plecoglassicida, the P.plecoglassicida were cultured at high pathogenic temperature and its ECP was prepared by the cellophane plate technique. The enzyme activities of ECP were measured at different temperatures（ hypothermy nonpathogenic temperature 12 ℃,high pathogenic temperature 18 ℃ and hyperthermy nonpathogenic temperature 28 ℃）.The results showed that the activities of amylase,serine proteinase,aspartate proteinase, pepsinase-like,chymotrpsin-like,lecithinase,acid phosphatase and alkaline phosphatase of ECP of P. plecoglassicida were affected by temperature notably,and at 28 ℃ their activities were significantly higher than at 12 ℃ or 18 ℃（ P〈0. 05） while the enzymatic activities of cysteine proteinase,aminopeptidase and hemolysis activity were not significantly changed（ P〉0. 05）. The results of this paper revealed that P. croceavisceral white spot dis-ease had high incidence at specific temperature interval（ 16 ~ 20 ℃） not because ECP possess higher activity at this temperature interval although the ECP is one of the pathogenic foctors. The research results of this paper could improve the understanding of pathogenesis of P. crocea visceral white spot disease.