生防细菌K2-1对大菱鲆病原菌的抑制作用及其抗菌特性分析

Antimicrobial activity of a biocontrol bacterium strain K2-1 against selected pathogens of Scophthalmus maximus and its antimicrobial property analysis

为探讨生防细菌应用于水产养殖动物细菌病防治的可行性,作者从厦门市海沧港口污泥中筛选到一株蜡状芽孢杆菌（Bacillus cereus）K2-1,利用琼脂扩散法发现其发酵上清对大菱鲆（Scophthalmus maximus）养殖常见致病菌——副溶血弧菌（Vibrio parahaemolyticus）、爱德华氏菌（Edwardsiella）、哈维氏弧菌（Vibrio harveyi）、嗜水气单胞菌（Aeromonas hydrophila）、溶藻弧菌（Vibrio alginolyticus））有较强拮抗作用。进一步分析抗菌物质的部分特性,结果显示,蜡状芽孢杆菌（Bacillus cereus）K2-1发酵产生的抗菌物质含有蛋白（肽）类成分,该抗菌物质具有一定的耐热性,其在温度40-70℃的条件下保持较好的抑菌效果,对酸碱度也有很强的耐受力,pH在3.0-9.0范围内,活性降低少于15%,对紫外线不敏感,对胰蛋白酶、胃蛋白酶、木瓜蛋白酶也不敏感,但对蛋白酶K敏感。从实验结果可以初步确定该菌具有较好的开发价值。

In order to study the possibility of using biocontrol bacterium for control and prevention of aquatic diseases caused by bacterial pathogens, a bacterium strain K2-1, identified as Bacillus cereus, was screened out from the mud of Haicang harbor, Xiamen, China. Antibacterial test was conducted using an agar diffusion method, and the result showed that the supernatant of strain K2-1 could inhibit the growth of some common pathogens related with Scophthalmus maximus diseases during farming including Vibrio parahaemolyticus, Edwardsiella, Vibrio harveyi, Aeromonas hydrophila and Vibrio alginolyticus. Further study of its antibacterial substance property was implemented, and it revealed that the bioactive substance produced by strain K2-1 was a protein（peptide）. This antibacterial protein was thermal stable, and it kept high antimicrobial activity under temperature ranging from 40 ℃to 70 ℃, and it was also of high acid and alkali tolerance, with its antibacterial activity decreasing less than 15% in the rang of p H 3.0 to 9.0. Enzymatic treatment test showed that this antibacterial protein was resistant to most protease including trypsase, pepsase and papain, but it was sensitive to protease K. All the these results showed that the strain K2-1 had high development and application values in the future.