碩士 / 國立海洋大學 / 水產養殖學系 / 87 / The investigation was conducted to study the properties and pathogenesis of Aeromons hydrophila which was isolated from disease fresh water prawn(Macrobrachium rosenbergii).
Three strains,860312,860327and870121 used in study were isolated from Ping-Tong,southern Taiwan.These strains were identified to be Aeromons hydrophila-like according to a series of biochemical tests using API 20E kits、BIOLOG GN system,and biochemical plate and tube tests.The reaction were compared with one reference strain of A hydrophila ATCC 13444.
In antibiotics sensitivity assay, all the strains were sensitive to chloramphenicol、ciprofloxacin、kanomycin、nalidixic acid、oxytetracycline and tetracycline while resistant to ampicillin、cephalothin、penicillin G,and vancomycin.
The extracellular products（ECP） of these three strains possessed high proteolytic activity using hide powder-azure digestibility assay. The proteolytic activities of ECP from strains 860312, 860327 and 870112 were 3082,2452 and 3034 HPA units / mg protein,respectially.
All the ECPs of these three strains exhibited hydrolysis against casein、 gelatein and esculin.The proteolytic activity of ECP from strain 860312 was demonstrated to be heat-stable.Since its activity was only partially inactivated in 20%. after heating at 100℃ for 30 min., The optimal pH of the ECP proteases was 4.The proteolytic activity of ECP was completely inhibited by N-ethylmaleimide suggesting that it was a cysteine protease.
The bacteria and its ECP were lethal to Macrobrachium rosenbergii with LD50 vaules of 4.12×103 CFU/ g body weight and 1.438 *g / g body weight,respectively.
The molecular mass of the protease was 94 kDa as estimated by SDS-PAGE.The ECP of strain 860312 was partially purified through various purification steps including HIC-FPLC, HP-FPLC and MonoQ-HPLC chromatography. The partially purified protease was lethal to the prawn with the LD50 value of 1.813 *g / g body weight . The optimal pH of the protease was 4 and was heat stable. The partially purified protease was completely inhibited by cysteine protease inhibiitors─( L-cysteine and N-ethylmaleimide) and partially inhibited by E-64(trans-epoxysuccinyl-L-leucylamido-(4-guanidino) butane, Boehringer, Mannheim, Germany), another cysteine protease inhibitors.
| Identifer | oai:union.ndltd.org:TW/087NTOU0086014 |
| Date | January 1999 |
| Creators | 魏榮璋 |
| Contributors | Ping-Chung,Lin, 劉 秉 忠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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