瘤胃微生物中厭氧性真菌之黴菌毒素分解酵素基因選殖及應用(2/3)

2007-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/692576摘要：黴菌毒素為黴菌產生之次級代謝物，對人體及畜禽均會產生嚴重的危害。穀物在採收前後均有可能受黴菌毒素污染，故其防範極為不易。而目前全球氣候暖化的結果，穀物受黴菌毒素污染的情形更為普遍。此外，大部份的黴菌毒素性質安定，加工後依然會殘留在食品或飼料中。畜禽食用受黴菌毒素污染的飼料將影響其生長繁殖性能，導致經濟上嚴重的損失。目前多以矽酸鋁或有機聚合物吸附飼料中的黴菌毒素，吸附法雖然可以減少黴菌毒素被動物吸收而降低其危害，但同時亦減少營養成分的吸收而導致飼料效率的降低。此外，吸附劑僅對黃麴毒素(aflatoxin)等極性的黴菌毒素具有較佳之吸附效果，但對deoxynivalenol (DON)及zearalenone (ZON)等二種黴菌毒素之效果極為有限。因此，尋求其他方法以解決穀物中黴菌毒素污染所致之危害，實有其必要性。目前已有許多研究證實瘤胃微生物具有分解黴菌毒素的能力，因此，本計畫擬自瘤胃微生物中篩選具有分解黴菌毒素DON 及ZON 能力的厭氧性真菌，經由建構其cDNA library 後，選殖黴菌毒素分解酵素基因，並將黴菌毒素分解酵素基因建構於酵母菌表達系統中，以進行黴菌毒素分解酵素的大量產製，同時亦評估該重組黴菌毒素分解酵素之活性及應用性。<br> Abstract: Mycotoxins are toxin secondary metabolites produced by fungi. Most of them are heat-stable and can not be destroyed by food and feed processing. The fact that contamination in grains can happen pre- and post-harvest makes it extremely difficult to control the spread of mycotoxins. Moreover, the change of global climate, such as “green-house effect”, has created an environment more favorable to the growth of some fungi. As a consequence, the economical loss associated with impaired animal health and performance due to consumption of mycotoxins has become a serious issue in the industry. Traditionally, elimination or reduction of contaminated mycotoxins in feed can be achieved by physical methods. The physical approaches are basically the addition of adsorbents, such aluminosilicate or organic polymers, into the feed to prevent mycotoxins absorbed by animals. Nevertheless, the binding capability of these adsorbents is not specific to mycotoxins, which may decrease the availability of soluble nutrients in digesta and reduce feed efficiency. In addition, physical absorption is only effective on mycotoxin molecules with polarity, such as aflatoxins, but not effective on deoxynivalenol (DON) or zearalenone (ZON). Ruminal microorganisms have been demonstrated to possess the ability to degrade mycotoxins. Therefore, this research aims at screening the ruminal anaerobic fungi possess the ability to degrade DON and ZON. The genes of the mycotoxin-degraded enzyme will be cloned and expressed in high efficiency expression system. The application of the recombinant enzymes will also be estimated.黴菌毒素瘤胃微生物厭氧性真菌mycotoxinruminal microorganismanaerobic fungi瘤胃微生物中厭氧性真菌之黴菌毒素分解酵素基因選殖及應用(2/3)