固定化增殖细胞发酵半纤维素糖类的研究

采用海藻酸钠包埋及进一步增殖培养，将休哈塔假丝酵母（ＣａｎｄｉｄａｓｈｅｈａｔａｅＲ）的细胞密集固定在凝胶珠表层，大大减小了传递阻力，为该菌的“半好气”发酵创造了有利条件。试验结果表明，ＣａＣｌ２浓度以２％为宜，凝胶中掺入适量的Ａｌ２Ｏ３（１．２％）能明显增加凝胶珠的机械强度及使用寿命。固定化增殖细胞能够利用己糖和戊糖及８０ｇ／ｌ的混合糖（己糖与戊糖各占一半）。经１２ｈ发酵，糖的利用率达９０．５％（相同条件下的游离细胞发酵需４８ｈ）。混合糖发酵的适宜条件为：温度３４～３６℃；初始糖浓度８０ｇ／Ｌ；通气量３．３ｍｌ／ｍｌ发酵体积·ｈ。固定化休哈塔假丝酵母能成功地发酵玉米秆水解液、杨木水解液及亚硫酸盐制浆废液，酒精得率达理论值的９０％以上，具有广阔的实际应用前景。

Fermentation of Hemicellulosic Sugars by Immobilized Candida Shehatae

By entrapping into calcium alginate gel and further incubation, Candida Shehatue R cells were densely immobilized in the periphery of the gel beads ,thus reduced the internal diffusion limitation and created favourable environment for semiaerotric fermentation of Candida Shehatae.The research results showed that 2% calcium chloride was suitable for immobilization and that mixing 1. 2% aluminium oxide into alginate gel could improve the mechanical strength and permanence of the beads obviously.The immobilized growth cells could utilize both hexoses and pentoses ,the utilization efficiency of 80g/L sugar mixture (glucose to xylose, 1: 1) was 90. 5% after 12h fermentation (48h fermentation for free cells). The optimal fermentation conditions of sugar mixture were as follows: temperature, 34～36℃, initial sugar concentration, 80g/L ,and air supply rate, 3. 3ml/ml·h. It was found that this immobilized biocatulyst can also effectively ferment spent sulphite liquor,corn stover hydroysate,and aspen wood hydrolysate. Ethanol yields were 90% or higher of the theoretical, which presented broad prospects for industrial applications.