1株副干酪乳酸菌S-4对致病弧菌的抑制特性研究

针对弧菌病害的防治，选取了一株副干酪乳酸菌(Lactobacillus paracasei)S-4对4种致病弧菌进行体外拮抗实验，并在此基础上比较了不同发酵时长及稀释倍数的上清液对弧菌的抑制作用，同时探究了抑菌物质特性及进行共培养拮抗实验.结果显示:副干酪乳酸菌S-4对4株致病弧菌均具有显著的抑制作用.副干酪乳酸菌S-4生长过程中，0~16 h的上清液无抑菌活性，20 h后开始表现出对4株弧菌的抑制作用；36 h时的上清液对创伤弧菌、哈维氏弧菌、副溶血弧菌的抑制率大于95.42%，且该上清液3倍稀释后的抑菌活性无显著降低，为最佳收获时间；72 h时的上清液对溶藻弧菌的抑制率达到95.72%，6倍稀释后的抑菌活性无显著降低，为抑制溶藻弧菌的最佳收获时间.进一步探究菌株间的相互拮抗表明:副干酪乳酸菌S-4在共培养4~6 h就表现出明显的抑菌活性，比上清液提前12 h产生抑制效果，在培养初期就能有效抑制弧菌的生长.生化分析表明:抑菌物质对过氧化氢酶、蜗牛酶、胃蛋白酶不敏感，与多肽类物质无关，酸碱中和后抑菌活性完全消失，推测为有机酸.本研究表明:副干酪乳酸菌S-4对4株常见致病弧菌具有较强抑制作用，在水产养殖中具有潜在应用价值.

The Inhibition of Pathogenic Vibrios with Lactobacillus Paracasei S-4

A strain of lactic acid bacteria S-4, identified as Lactobacillus paracasei S-4 according to the nucleotide sequence of its 16S rDNA, was used to conduct experiments to observe its antagonistic effect on four strains of vibrio. This study compared the antibacterial effect of supernatant with different culture durations and dilution ratios on vibrio and explored the competition of L. paracasei S-4 in co-cultivation with vibrio in vitro. The results showed that the supernatant had no inhibitory activity at 16 h of fermentation but showed inhibitory activity to 4 strains of vibrio after 20 h culture. And 36 h supernatant was the best harvest time for inhibiting V. harveyi, V. vulnificus and V. parahaemolyticus, when the inhibition percentage reached more than 95.42% and there was no significant decrease of inhibitory effect after 3-fold dilution. But to V. alginolyticus, 72 h supernatant was the best harvest time and showed a 95.72% inhibition ratio, and 6-fold dilution of it exhibited no significant difference. L. paracasei S-4 in co-cultivation with vibrio started to reduce the 4 strains of vibrio at 4-6 h, its inhibitory activity appearing 12 h ahead of supernatant, indicating that L. paracasei S-4 was able to inhibit the growth of vibrio at the beginning of culture. Biochemical assay showed that the inhibitory compounds were insensitive to catalase, pepsase and snailase, and ultrafiltration and cold ethanol precipitation could not eliminate their inhibitory activity. But the inhibitory activity disappeared completely when supernatant pH was adjusted to neutral, indicating that organic acid may play an important role in bacteriostatic activity. The results of this study showed that L. paracasei can strongly inhibit 4 strains of vibrio and has potential value of application in aquaculture.