碩士 / 慈濟大學 / 生命科學研究所 / 97 / Combating microbial pathogens in aquaculture industry has been heavily relied on application of antibiotics, and as a result, this approach has fostered the rise of resistant bacteria. We attempted to use environmental and commensal bacteria as an ecological control agent against fish pathogens. Nine hundred and eighty five isolates were obtained from seawater and cobia intestine, 21 of them shown inhibitory activity against Photobacterium damselae piscicida, Listonella anguillarum or Vibrio vulnificus. Eleven isolates were proved to be non-pathogenic in zebrafish safety test. Two isolates demonstrating cell-associated and two demonstrating secreted pathogen inhibition activities were selected and compared, and isolate L19 was selected for further study due to its high potency.
L19 was identified as Pantoea ananatis by 16S rDNA analysis. Inhibition against V. vulnificus and P. damselae piscicida can be achieved by co-culture with L19 culture supernatant or live bacteria. L19 supernatant treatment damaged pathogen cell surface, as revealed by transmission electron microscopy. The inhibitory substance in culture supernatant is protease insensitive and acid resistant, and can pass the 10-kD molecular sieve. Addition of L19 can induce aggregation of P. damselae piscicida, which may provide additional protection. L19 reduced mortality in zebrafish receiving immersion challenge of V. vulnificus, and can persist in low nutrient environment for at least 15 days. These characteristics make L19 eligible for further field test in aquaculture as a pathogen-inhibiting probiotic.
| Identifer | oai:union.ndltd.org:TW/097TCU05105010 |
| Creators | Yi-Ting Hu, 胡逸廷 |
| Contributors | Chun-Yao Chen, 陳俊堯 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 95 |
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