细菌QJ2对对虾病原性哈维氏弧菌的拮抗作用

The antagonistic activities of bacterial strain QJ2 against shrimp pathogenic Vibrio harveyi

对气味黄杆菌（Ｆｌａｖｏｂａｃｔｅｒｉａ ｏｒｄｏｒａｔｕｍ） ＱＪ２及其去细胞上清液（ＣＦＳ）对对虾病原性哈维氏弧菌（Ｖｉｂｒｉｏｈａｒｖｅｙｉ）Ｚ３Ｇ２ Ｅ０２２的拮抗作用进行了研究。ＱＪ２的ＣＦＳ对病原菌表现显著的拮抗性能，在６ｈ内使数量为１０５－１０６ｃｆｕ·ｍＬ的病原菌（Ｚ３、Ｅ０２２均降为０。经热、酸碱、蛋白酶处理的ＣＦＳ，抑菌活性均有不同程度下降，结果为；经６０℃处理以６０ｍｉｎ的ＣＦＳ，经６ｈ使Ｚ３Ｇ２细菌数降为０，经１５ｍｉｎ使Ｅ０２２数量降为最低，为初始菌数的６３．０％：经１００℃处理１０ｍｉｎ，ＣＦＳ使Ｚ３Ｇ２和Ｅ０２２数量分别在１ｈ和１５ｍｉｎ降为最低，各为初始菌数的２３．７％和７２．１％；经ｐＨ４时作用３０ｍｉｎ，ＣＦＳ使Ｚ３Ｇ２和Ｅ０２２数量分别在１５ｍｉｎ和１ｈ降为最低，各为初始菌数的８８．３％和１５．９％，而经ｐＨ１２处理３０ｍｉｎ后，ＣＦＳ没有使病原菌数下降，但使病原菌以比对照组细菌低的速率缓慢上升；经蛋白酶Ｋ于３７℃作用６０ｍｉｎ后，ＣＦＳ在１５ｍｉｎ时使Ｚ３Ｇ２和Ｈ０２２数量降为最低，各为初始菌数的１５．０％和６６．１％。在人工水体中，ＱＪ２活菌对病原菌也具有显著的拮抗?

The antagonistic activities of living bacteria of strain QJ2, Flavobacterium ordoratum and its cell-free supernatant (CFS), were studied against two shrimp pathogenic strains of Vibrio harveyi, Z3G2 and E022. The CFS of QJ2 exhibited evident antagonistic activties against the pathogens, reducing the numbers of both pathogens from 105- 106 cfu·Ml-1 to zero in 6h. The inhibitory activities of CFS decreased after treatment by heat, acid and alkali,and proteinase. The number of Z3G2 was decreased to zero in 6h by the inhibition of CFS treated at 60℃ for 60 min, and E022 maximally to 63.0% of the initial number in 15min; while Z3G2 and E022 reduced maximally to 23.7% of the initial number in 1h and 72.1% in 15 mm, respectively, by the CFS treated at 100℃ for 10 nun. The numbers of Z3G2 and E022 were decreased maximally to 88.3% of the initial number in 15 mm and 15.9% in lb. respectively, by the inhibition of CFS treated by pH 4 for 30 mm; both bacteria increased gradually with a growth rate lower than that of the controls, by the CFS treated by pH 12 for 30 ruin. By the inhibition of CFS exposed to proteinase K at 37℃ for 1h, both Z3G2 and E022 decreased maximally to 15.0% and 66.1% of the initial number in 15 min, respectively. In the artificial seawater system, the living bacteria of QJ2 showed evident antagonistic activities to pathogens in 24h, reducing the number of Z3G2 and E022 by 1.6 Log1o and 2.4 Log10orders of magnitude, respectively. Results showed that QJ2 produced bacteriocin to antagonize the pathogenic Vibrio harveyi.