具黴菌毒素分解能力之芽孢桿菌的鑑定與特性分析

Abstract

穀物在生長、收成、運輸或儲存期間，常發生黴菌在穀物上生長的情形，其所產生的黴菌毒素（mycotoxin）可能會進一步汙染穀物，導致糧食與經濟作物的損失。人類若誤食受黴菌毒素汙染之食物，也將導致慢性或急性疾病。因此在農業與食品加工上，需藉由防止黴菌汙染或去除黴菌毒素以避免上述損害發生。本實驗針對由發黴玉米中所篩出的菌株，LN，進行基本生理生化特性與黴菌毒素分解能力的分析，並探討此菌株製成益生菌之可能性。經鑑定試驗結果顯示， LN 屬於Bacillus amyloliquefaciens；在黴菌毒素移除試驗中，LN 與在 LB 培養液中的玉米烯酮（zearalenone）作用24小時後便可將其完全移除，且菌株主要移除此黴菌毒素的方式為降解作用。以模擬宿主腸胃道環境的酸及膽鹽耐受性試驗顯示，孢子化的 LN 可在 pH 2 與 3 的 環境中存活，並可於含有 0.3% oxgall 的LB培養液中生長；細胞吸附試驗顯示 LN 對人類大腸癌細胞 Caco-2 具有吸附能力；酵素試驗則顯示 LN 具有產生聚木糖酶（xylanase）、羧甲基纖維素酶（CMCase）、澱粉酶（amylase）與蛋白酶（protease）等特性。綜合以上結果，B. amyloliquefaciens LN 除了具有降解玉米烯酮與產生聚木糖酶、羧甲基纖維素酶、澱粉酶與蛋白酶等能力外，並展現多項益生菌的特性，故具有做為食物或飼料用微生物製劑的潛力。

During the periods of crops growing, harvest, transportation, and storage, mycotoxin contamination takes place all the time, leading to a great loss in food and economy. It also poses a threat to the health of animals and human beings if contaminated grains are accidentally processed as feed or food. Therefore, the preventive measure for fungi-growing and mycotoxin production, or therapeutic method for mycotoxin-removing should be executed. In this research, Bacillius amyloliquefaciens LN, a bacterial strain isolated from moldy corns and named after the author of this thesis, was characterized and investigated for its mycotoxin removing ability and its potentiality as food or feed additives. As the results, LN belongs to Bacillus amyloliquefaciens based on molecular and biochemical identification, and it can discriminate the content of zearalenone (ZEN) in LB broth after 24 hr culturing, and the removal mechanism is mainly by degradation instead of adsorption; In the assay for its probiotic feature determination, LN spore can survive in pH 2 and pH 3 solutions and can grow in LB broth containing 0.3% oxgall, two of the solutions in this assay simulate the conditions of stomach and guts separately, and thus the results suggest that LN can live in the digestive system. In Caco-2 cell adhesion assay, the adhesion rate of LN with Caco-2 cell is low. In the assay of enzyme activity determination, LN has xylanase, CMCase, amylase and protease activies. According to the multiple probiotic traits found in LN and its mycotoixn removing ability, it is promising for LN processed as feed or food additives.