Abstract:Vibrios were common microbe in marine aquaculture. Most of them such as Vibrio anguillarum, V. harveyi and V. parahaemolyticus etc. were opportunistic pathogen to aquaculture animals. In the latest years, shrimp culture worldwide was subjected to heavy economic loss which was caused by V. parahaemolyticus infection. In order to find a high effective and safety method to control the serious shrimp vibrio disease, instead of using antibiotics, screening and using probiotics is a promising way. In this study, a strain was isolated from a shrimp pond and designated as 2013082515 (Strain 15). The antibacterial effect and minimum antibacterial concentrations of Strain 15 were analyzed using V. anguillarum, V. harveyi and V. parahaemolyticus as indicator bacteria. At the same time, the antibacterial effect of Strain 15 against other seven marine vibrios including V. vulnificus, V. alginolyticus, V. diabolicus, V. campbellii, V. natriegens, V. brasiliensis and V. rotiferianus was analyzed. Biological safety evaluation test on Strain 15 used as probiotic was conducted by injection and immersion challenge. The results showed that Strain 15 had obvious antibacterial effect against three indicator bacteria. Furthermore, the strongest antibacterial effect presented on V. anguillarum with an inhibition zone around (34.90±0.36) mm, the second largest inhibition zone presented on V. harveyi around (25.74±0.17) mm; The minimal inhibitory concentration of Strain 15 on V. anguillarum, V. harveyi and V. parahaemolyticus was 2.50×104 CFU/ml, 2.50×105 CFU/ml, and 2.50×105 CFU/ml respectively, and the antibacterial effect of Strain 15 against other 7 vibrios were obtained in different degree. Data also showed that Strain 15 at high concentrations (injection challenge 1.84×107 CFU/ml, immersion challenge 4.17×107 CFU/ml) had potential toxicity to shrimp. In order the identify Strain 15, both gas chromatographic analysis of bacterial whole cell fatty acids and 16S rDNA sequencing were employed. The results showed that Strain 15 was a Pseudoalteromonas sp. Results from this study could provide technical support for developing biological agents used for preventing vibriosis in aquatic animals.
