In recent years, the skin and muscle hemorrhagic ulcer occurred in grouper hatchery, suggesting that the bacteria extracellular protease was involved. In this study I surveyed the extracellular protease activity of marine bacteria and investigated the characteristics of the pathogen isolated from diseased grouper. The sampling sites of background survey were located along the coast of Taitung. The cultured media were MB2216 and PPESII. The extracellular protease activity was measured using milk seawater medium (MS) and dye-modified proteins of azocasein and azoalbumin. The extracellular protease activities of the marine bacteria were 1~5 U/mg. The average protease activities of the bacteria from MB2216 media were higher than those from PPESII media. The extracellular protease activity assay using azocasein and azoalbumin had similar tendency but the result by the clear zone measurement on the MS medium was of high variations. The FI-02 isolated from the diseased grouper skin was identified as Aeromonas hydrophila by the biochemicial characteristics and 16S rDNA sequence analysis. FI-02 was able to grow on the LB broth with 0~4% NaCl. The FI-02 was resistant to ampillicin, cefazolin, erythomycin, sulfisoxazole, whereas it was sensitive to streptomycin, doxycline, norfloxacin, cefotazime, oxolinic acid, and tetracycline. When FI-02 growing in the four media, the extracellular protease activities were higher than 4 U/mg. The highest protease activity was 6.08 U/mg when the bacteria grew on the LB medium. After heating on 27, 37, 42 and 56¢J for 20 mins, the protease activities remained the same. In the investigation of the fish immunity, owing to the complex compositions of the fish serum, no conclusion can be drawn on the specificity of the antibody against the bacterium.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0114104-214302 |
| Date | 14 January 2004 |
| Creators | Wang, Hsiao-ting |
| Contributors | Jong-kang Liu, Chi-hsin Hsu, Chan-shing Lin |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0114104-214302 |
| Rights | not_available, Copyright information available at source archive |
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