碩士 / 國立臺灣海洋大學 / 食品科學系 / 102 / Tilapia is one of the most important aquaculture and traded species. The major diseases in tilapia are due to bacterial infection, with major pathogens being Aeromonas hydrophila, Streptococcus iniae and Edwardsiella tarda. Although antibiotic treatment can cure bacterial infection in Tilapia, the issues of antibiotic resistance and residue are also raised up. Currently, the concept of probiotic, especially from lactic acid bacteria (LAB), which are widely used for human functional food, is applied into aquaculture for various fish and animals.The aims of this research are to isolate LAB from the intestines of healthy tilapia, to screen LAB with strong antibacterial activity against fish pathogens due to extracellular antibacterial substance production, to test the susceptibility of chosen LAB to simulated gastric juice and intestinal juice. Finally, some characteristics of the antibacterial substances produced by LAB, including themal and pH effects on activity and susceptibility to protease,α-amylase and catalase were investigated. Thirty-three strains of LAB from intestines isolated, which the cultured filterates of 5 strains of STJ 2506, STJ 2507, FTW 2511, STJ 3707 and STW 3717 were demonstrated to have larger inhibition zone against S. iniae and A. hydrohila. Except STJ 2507, the survival rates for rest of four strains in simulated gastric juice (3 hr) followed by in simulated intestinal juice (6 hr) were greater than 65%. However, only STJ 2506, STJ 3707 and STW 3717 show great activity in minimal lethal concentration (MLC) test against 13 phatogens, that is 100 mg/mL. All of the extracellular substances from these 3 strainsexhibited the highest antimicrobial activity at pH 5 and maintain above 50% antimicrobial activity after heating at 121℃ for 20 min and resistant to functions of protease and α-amylase. However, these three extracellular substances maintain 84% antimicrobial activity after treatment of catalase.
| Identifer | oai:union.ndltd.org:TW/102NTOU5253040 |
| Date | January 2014 |
| Creators | Derrick Khor, Tze-Hao, 許智豪 |
| Contributors | Tsai, Guo-Jane, 蔡國珍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 73 |
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