碩士 / 國立屏東科技大學 / 熱帶農業研究所 / 89 / Growth of a bacterial pathogen, Lactococcus garvieae, was examined in TSB medium containing different concentrations of copper sulfate (CuSO4) at 0, 0.1, 0.2, 0.3, 0.4 mg/l; potassium permangnate (KMnO4) at 0, 0.3, 0.6, 1.0 mg/l; and benzalkonium chloride (B.K.C.) at 0, 0.3, 0.6, 1.0 mg/l. L. garvieae grew well in all of the modified media. The giant freshwater prawn, Macrobrachium rosenbergii,of the size of 9-13 g, was challenged with L. garvieae at 4×106 cfu/prawn. The pathogen was previously incubated for 24 h in TSB medium containing different concentrations of CuSO4, KMnO4 and B.K.C. After the challenge, the prawn was placed in water for monitoring pathogenicity of L. garvieae for 168 h. The results showed that the cumulative mortality was significantly higher (p<0.05) when the prawn was challenged with L. garvieae, which had been incubated in the medium containing CuSO4 at 0.4 mg/l, KMnO4 at 1 mg/l and B.K.C. at 0 mg/l, than at any other concentrations of the same chemical.
The prawn of the size 9-13 g was challenged with L. garvieae (4×106, 2×105 and 3×106 cfu/prawn), which had been previously incubated for 24 h in TSB, and then the prawn was placed in water containing different concentrations of CuSO4, KMnO4 and B.K.C. The results showed that in the tests involving CuSO4, when challenged with L. garviea at a dose of 4 x 106 cfu/prawn, the mortality of the prawn was significantly higher when it was cultured in water containing CuSO4 at 0.4 mg/l than that at 0.2 mg/l and 0.3 mg/l. The mortality was, in turn, higher at 0.2 mg/l and 0.3 mg/l than that at 0 and 0.1 mg/l. When the prawn was challenged with L. garvieae at a reduced dosage at 2 x 105 cfu/prawn, the cumulative mortality increased with the increase of the concentrations of CuSO4 at 0.2 mg/l to 0.4 mg/l. There was no mortality observed when the prawn was exposed to CuSO4 at 0.1 mg/l over a period of 168 h. In the tests with KMnO4, when the prawn was challenged with L. garvieae at a dosage of 4 x 106 cfu/prawn, the survival rate was significantly lower (p<0.05) at 0.6 mg/l and 1.0 mg/l than that at 0 mg/l. The survival rate at 0.3 mg/l was significantly lower than that at 0 mg/l. When the dosage of L. garvieae was reduced to 3 x 106 cfu/prawn, the mortality rate at 0.3 mg/l was lower than that at 1.0 mg/l. In the tests with B.K.C., when the prawn was challenged with L. garvieae at a dosage of 4 x 106 cfu/prawn for 168 h, the survival rate at 0 mg/l was significantly higher (p<0.05) than that at any other concentrations. The results indicated that the survival of the prawn was enhanced when it was exposed to CuSO4 and KmnO4 at low concentrations.
The total hemocyte count (THC), different hemocyte count (DHC), phenoloxidase activity (PO) and respiration burst in NBT reduction were examined after the molting prawn of the size 20-28 g was reared in a condition containing different concentrations of CuSO4, KMnO4 and B.K.C. No significant difference in hemocyte count was observed among the treatments. In the tests involving CuSO4, PO significantly decreased (p<0.05) with the increase of the exposure time. The respiratory burst significantly increased when the prawn was exposed to CuSO4 at 0.1 mg/l for 48 h. In the tests involving KMnO4, PO significantly decreased (p<0.05) with the increase of the concentration of KMnO4 after the exposure time of 96 h. The respiratory burst, however, increased with the increase of the exposure time in KMnO4. In the tests involving B.K.C., PO decreased, whereas the respiratory burst increased, with the increase of the exposure time in B.K.C. The results showed that the pathogenicity of increased when the prawn was exposed to a condition containing CuSO4 and KMnO4, but decreased when it was exposed to a condition containing B.K.C. The immune system was modulated when the prawn was exposed to the concentrations of CuSO4 and KMnO4. When the prawn was exposed to CuSO4 at 0.1 mg/l and KMnO4 at 0.3 mg/l, its resistance against L. garvieae increased. Conversely the susceptibility to L. garvieae increased when the prawn was exposed to CuSO4 at 0.2 mg/l and KMnO4 at 0.6 mg/l. Under the same conditions, the prawn generated higher level of superoxide anion, which was suspected to cause cytotoxicity in the prawn.
| Identifer | oai:union.ndltd.org:TW/089NPUST643015 |
| Date | January 2001 |
| Creators | Cheng-Hsien Wang, 王靜嫻 |
| Contributors | Winton Cheng, 鄭文騰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 91 |
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