碩士 / 國立嘉義大學 / 生物農業科技學系碩士班 / 100 / Because the world marine fishing production has stalled, aquaculture is increasingly important for producing animal protein for human beings’ consumption. Owing to the advance of biotechnology, the aquaculture production has increased every year. Tilapia farming is especially popular in aquaculture because it has many good features such as the environment adaptable, omnivorous, fast-growing, high feed conversion ratio. Intensive tilapia farming is economic, yet it allows fish diseases to spread easily. Although tilapia is known to resist strongly to diseases, infection of Streptococcus in tilapia has already been reported in recent years which have resulted in many significant fish farming impacts. In this study, one novel bacterial pathogen, Citrobacter freundii, is isolated and characterized to cause the death of tilapia. Originally, eight single bacterial colonies are isolated from the diseased tilapia liver. Five different bacterial clones are later confirmed by the technology of random amplified polymorphic DNA (RAPD). The five isolated clones are then used to challenge tilapia. One of the five isolates, TpG, is successfully identified as a tilapia pathogen according to Koch's postulates. Alignment of TpG’s 16S rRNA sequence data results that it is Citrobacter freundii. This is the first report that Citrobacter freundii can cause the death of tilapia. The isolated Citrobacter freundii is further characterized to grow well in the LB medium containing 1% to 3% of NaCl with the temperatures ranging from 12 ° C to 37 ° C. It can also survive in the LB medium with the pH ranging from 5 to 9. The antibiotic minimal inhibition concentrations (MIC) of Citrobacter freundii is also assayed and listed as followed: Chloramphenicol (5 ug) 、 Neomycin (5 ug) 、 Tetracycline (5 ug) 、 Kanamycin (0.1 ug). These observations may provide valuable information regarding controlling the infection of Citrobacter freundii in tilapia.
| Identifer | oai:union.ndltd.org:TW/100NCYU5408007 |
| Creators | Tun-Sheng Huang, 黃惇聖 |
| Contributors | Wen-Hsing Chang, 張文興 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 88 |
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