Identification and Characterization of Pseudomonas sp. P9 Antagonistic to Pathogenic Vibrio spp. Isolated from Shrimp Culture Pond in Thua Thien Hue-Viet Nam

From shrimp culture ponds in Thua Thien Hue, isolates were obtained on PSA plates and screened for their activity against two pathogenic strains Vibrio sp. V7 and V10 isolated from diseased shrimps in culture ponds in Thua Thien Hue using the agar well-diffusion method. Among of the isolates, only strain P9 showed antagonistic activity against Vibrio sp. V7 and V10. Based on the cell morphology observed with a JEOL 5410 LV scanning electron microscope, biochemical reactions tested with GN card, and 16S rRNA nucleotide sequence used to search the GenBank database with the BLAST system, strain P9 was identified as Pseudomonas sp. P9. The 16S rRNA sequence of Pseudomonas sp. P9 has been deposited in the DDBJ/EMBL/GenBank database with the accession number HM854226. In addition, Pseudomonas sp. P9 also showed the ability to produce siderophore to acquire iron and extracellular enzymes to decompose organic compounds such as starch, protein and cellulose. Otherwise Pseudomonas sp. P9 was non-pathogenic to shrimp. Growth as well as production of the antagonistic component in TSBS of Pseudomonas sp. P9 showed over a wide range of pH, salinities and temperatures. Therefore, Pseudomonas sp. P9 can be considered as not only a candidate for control the shrimp disease but also a potential probiont for shrimp culture.