The main objectives of the present investigation were to control bacterial contamination in explants cultured in vitro. Lower contamination rates were obtained in leaf and shoot tip explants when surface sterilized by a two-step method. In the first step, the explants were sterilized with 0.5 % sodium hypochlorite for 15 min outside the laminar flow. In the second step, before resterilization in the laminar flow, the midrib of leaf explants and three leaves covering the shoot tip explants were removed and then sterilized with the same concentration of sodium hypochlorite used in the first step, for five minutes. The explants were washed 3-4 times with sterile distilled water after each sterilization step. Pre-treatment of explants (leaf, ovary, and shoot tip) with hot water (40.2-45.2℃) did not help in controlling contamination in in vitro cultures. Addition of Benlate®, an antifungal agent, in the culture medium was not useful in controlling contamination in leaf and ovary explants. Lower contamination rates were obtained in ovary and shoot tip explants pretreated with liquid MS medium containing either 500 mg/l cefotaxime for 3 days. Pretreatment of explants with antibiotics did not inhibit either callus formation in leaf explants or growth of shoot tip explants.本研究以彩虹鳥蕉(Heliconia psittacorum cv. Rhizomatosa)為材料，尋求降低培植體高污染率的方法。結果顯示經0.5％次氯酸鈉溶液外部消毒15分鐘之根莖新芽培植體，在無菌操作臺上切除2-3片外覆鱗片葉後，再以相同濃度次氯酸鈉溶液消毒5分鐘，能顯著降低細菌污染。葉片培植體則以相同的方法外部消毒後，縱切並除去部分主葉脈，再二次消毒5分鐘，也能降低細菌污染。培植體在外部消毒前先以40.2-45.2℃熱水處理1小時，對降低細菌污染的效果不顯著。子房和葉片培植體接種於免賴得殺菌劑1000mg/l之培養基，對細菌污染率也無明顯降低作用。但子房和莖頂培植體先在以添加500mg/l cefotaxime液體培養基中預處理3天，再繼代培養於固體培養基，則能有效降低細菌污染且對培植體無毒害作用
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