克鲁维酵母种间原生质体融合的研究

乳酸克鲁维酵母(Kluyueromyces lactis Y12—1)和脆壁克鲁维酵母(K.fragilis8554)是乳糖酶生产菌株。应用原生质体融合技术进行了两菌株种问融合的研究。通过试验．原生质体形成及再生的最佳条件为：对数期的细胞，2％的蜗牛酶．30℃酶解30分钟．原生质体形成率90％以上，再生率20%左右。原生质体融合由聚乙二醇(PEG)诱导。K.lactisY12-l不能旋酵菊糖；K.fragilis 8554不能同化D－松三糖和麦芽糖；利用二菌株自身的营养缺陷性质获得融合子。融合子既能发酵菊糖又能同化D－松三糖和麦芽糖；融合子的DNA含量约为二亲株之和；融合子的菌落形态与亲株相比有一定差别．在以乳糖为碳源的培养基中，融合子的乳糖酶产量提高14一l6％；连续15次传代，融合子稳定。

Study on Protoplast Fusion Between Kluyveromyces lactis and Kluyveromyces fragilis

Result of interspecific protoplasts fusion between Kluyveromyces lactis Y12-1 and K. fragilis 8554 induced by PEG were reported. The optimum conditions for efficient formation and regeneration of protoplast were observed. Fusion was carried out by treating suspension of protoplast derived from the cells of Y12-1 and 8554 with the fuso-gen containing 35% PEG. Y12-1 can't ferment inulin, while 8554 can't assimilate maltose and melezitose. Taking advantage of the auxotroph of the two parental strains, several fusants were obtained. Two genetically stable recombinants F87 and F101 were confirmed by the increased amount of chromosomal DNA per cell. A fusant's DNA con tent equals the additive amount of DNA of its parents. The lactase yield of fusant F87 is 113. 6% and 114. 3% while the fusant F101 is 116.1% and 116.8% of that of diploid Y12-1 and 8554 respectively.