The Methylene Blue dye Reduction Test(MBRT) is a novel method to evaluate yeast vitality. The effects of ion and nitrogen source on Saccharomyccs ccrevisiae vitality were studied by MBRT method in this paper, and the method was applied in the cultivation of yeast in the inferior material--cassava dregs. The role of ions and inorganic nitrogen source were analyzed and the results were showed as follows: the effect of K+ was notable and the optimum concentration was 0.015mol/L; Mg2+ was also important, while the concentration above 0.004mol/L can inhibit the growth of yeasts. Low concentration of Na+ and Ca2+ can slightly promote the yeast growth and vitality, the optimal concentration were 0.0025mol/L and 0.001mol/L, respectively. Urea was the better nitrogen source than ammonium sulfate and the optimal concentration was 2g/L. Yeasts were cultivated in saccharification liquid of cassava dregs with 2g/L urea and 0.015mol/L K+, and the number of yeasts increased 5 folds compared with that of the control culture, the value of yeast vitality was 105s (control culture was 256s).%亚甲基蓝还原实验法(MBRT)是一种新的评价酵母活力的方法,该文首次使用该方法考察了几种主要离子及无机氮源对酒精酵母生长的影响,并指导了劣质原料木薯渣糖化清液中高活力酵母的培养.从几种主要离子及无机氮源对酵母活力的影响结果初步分析得出如下结论,酵母生长过程中K+的作用最为明显,最适浓度为0.015mol/L;Mg2+是必须的,但当浓度超过0.004mol/L时,就会抑制酵母生长;低浓度的Na+与Ca2+对酵母生长有促进作用,最适浓度分别为0.0025mol/L、0.001mol/L.与硫酸铵相比,尿素是较好的无机氮源,最适浓度为2g/L.利用木薯渣糖化清液培养酵母时,添加2g/L的尿素及0.015moi/L钾离子后,可使培养出的酵母数增加6倍,酵母活力值为105s(空白为256s).
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