Identification of a marine antagonistic strain JG1 and establishment of a polymerase chain reaction detection technique based on the gyrB gene

摘要

A marine antagonistic bacterium, JG1, was isolated from rearing water of healthy turbot (Scophthalmus maximus) in Qingdao, China. Strain JG1 was Gram-negative, straight rod and motile by polar flagella. The colony, when cultured for 24 h under room temperature, produced a yellow pigment. On the basis of morphological, physiological and biochemical characteristics, along with 16S rDNA sequence analysis, JG1 was identified as Pseudoalteromonas flavipulchra. JG1 had good inhibitory effects on several bacterial pathogens of aquaculture in the genus Vibrio (V. anguillarum, V. alginolyticus, V. campbellii, V. harveyi, V. mimicus, V. parahaemolyticus and V. tubiashii) and Aeromonas (A. hydrophila and A. salmonicida). No mortality occurred 14 days after zebra fish and 7 days after mantis shrimp were intraperitoneally injected with JG1 at 106 CFU per animal, and 7 days after scallop and clam were immersed in JG1 at 107 CFU mL−1. A good antagonistic effect on several bacterial pathogens and nontoxicity to the above-mentioned animals make JG1 a potential probiotic in aquaculture. In addition, a fast detection technique based on polymerase chain reaction amplification of the gyrB gene was established to allow us to determine the fate of JG1 when it is applied in aquaculture in the future.