da Cunha Mário A A, Converti Attilio, Santos Júlio C, Ferreira Sylvia T S, da Silva Silvio S
Department of Science and Engineering, COQUI, Federal Technological University of Paraná, Via do Conhecimento Km 1, CEP 85503-390, Pato Branco, Paraná, Brazil.
Appl Biochem Biotechnol. 2009 Jun;157(3):527-37. doi: 10.1007/s12010-008-8301-5. Epub 2008 Jul 17.
Viable cells of Candida guilliermondii were immobilized by inclusion into polyvinyl alcohol (PVA) hydrogel using the freezing-thawing method. Entrapment experiments were planned according to a 2(3) full factorial design, using the PVA concentration (80, 100, and 120 g L(-1)), the freezing temperature (-10, -15, and -20 degrees C), and the number of freezing-thawing cycles (one, three, and five) as the independent variables, integrated with three additional tests to estimate the errors. The effectiveness of the immobilization procedure was checked in Erlenmeyer flasks as the pellet capability to catalyze the xylose-to-xylitol bioconversion of a medium based on sugarcane bagasse hemicellulosic hydrolysate. To this purpose, the yield of xylitol on consumed xylose, xylitol volumetric productivity, and cell retention yield were selected as the response variables. Cell pellets were then used to perform the same bioconversion in a stirred tank reactor operated at 400 rpm, 30 degrees C, and 1.04 vvm air flowrate. At the end of fermentation, a maximum xylitol concentration of 28.7 g L(-1), a xylitol yield on consumed xylose of 0.49 g g(-1) and a xylitol volumetric productivity of 0.24 g L(-1) h(-1) were obtained.
采用冻融法将季也蒙毕赤酵母的活细胞包埋于聚乙烯醇（PVA）水凝胶中进行固定化。包埋实验根据2(3)全因子设计进行规划，将PVA浓度（80、100和120 g L(-1)）、冷冻温度（-10、-15和-20℃）以及冻融循环次数（一次、三次和五次）作为自变量，并结合另外三个测试来估计误差。在锥形瓶中检查固定化程序的有效性，即基于甘蔗渣半纤维素水解产物的培养基中，颗粒催化木糖向木糖醇生物转化的能力。为此，选择木糖醇对消耗木糖的产率、木糖醇体积生产力和细胞保留率作为响应变量。然后将细胞颗粒用于在搅拌罐反应器中进行相同的生物转化，该反应器在400 rpm、30℃和1.04 vvm空气流量下运行。发酵结束时，获得的木糖醇最大浓度为28.7 g L(-1)，木糖醇对消耗木糖的产率为0.49 g g(-1)，木糖醇体积生产力为0.24 g L(-1) h(-1)。
