PHENOTYPIC AND MOLECULAR CHARACTERIZATION AND THE LAMP DETECTION OF PATHOGENIC VIBRIO NATRIEGENS ISOLATED FROM DISEASED PENAEUS JAPONICUS
日本对虾(Penaeus japonicus)病原需钠弧菌(Vibrio natriegens)表型与分子特征及LAMP检测方法的建立

A mass mortality of zoea of Penaeus japonicus broke out in a hatchery in Lianyungang, Jiangsu Province. The dominant bacterial colonies were isolated and confirmed the pathogenicity by challenge experiments, the LD50 of the isolates to P. japonicus was 1.8×106 CFU/ml. The morphological, physiological, biochemical characteristics were examined, and the 16S rRNA gene, gyrB gene and rpoA gene sequences were amplified and compared with sequences stored in the databases, from which molecular phylogenetic trees were constructed. The isolates showed that properties and biochemical characteristics similar to Vibrio natriegens. The sequenced 16S rRNA gene of strain JL120508 (GenBank accession No.JX993271) was 1461bp, the gyrB gene of strain JL120508 (GenBank accession No.JX993272) was 1179bp, and the rpoA gene of strain JL120508 (GenBank accession No.JX993273) was 1038bp in length. The 16S rRNA, gyrB gene and rpoA gene sequences displayed high similarity to the genes of V. natriegens from GenBank database. The phylogenetic trees based on 16S rRNA, gyrB and rpoA sequences, JL120508 clustered with the V. natriegens strains, and was supported by high bootstrap value, strongly supporting the assignment of isolate JL120508 to V. natriegens. In addition, specific primers were designed based on the gyrB gene sequences, and the loop-mediated isothermal amplification (LAMP) detecting V. natriegens was established. The LAMP is suggested to be useful in the specific and rapid diagnose and epidemiological investigation of the disease caused by V. natriegens.