Institute of Chemistry, University of Campinas, Campinas, SP 13083-970, Brazil.
AMB Express. 2013 May 30;3(1):31. doi: 10.1186/2191-0855-3-31.
Saccharomyces cerevisiae cells were immobilized in calcium alginate and chitosan-covered calcium alginate beads and studied in the fermentation of glucose and sucrose for ethanol production. The batch fermentations were carried out in an orbital shaker and assessed by monitoring the concentration of substrate and product with HPLC. Cell immobilization in calcium alginate beads and chitosan-covered calcium alginate beads allowed reuse of the beads in eight sequential fermentation cycles of 10 h each. The final concentration of ethanol using free cells was 40 g L-1 and the yields using glucose and sucrose as carbon sources were 78% and 74.3%, respectively. For immobilized cells in calcium alginate beads, the final ethanol concentration from glucose was 32.9 ± 1.7 g L-1 with a 64.5 ± 3.4% yield, while the final ethanol concentration from sucrose was 33.5 ± 4.6 g L-1 with a 64.5 ± 8.6% yield. For immobilized cells in chitosan-covered calcium alginate beads, the ethanol concentration from glucose was 30.7 ± 1.4 g L-1 with a 61.1 ± 2.8% yield, while the final ethanol concentration from sucrose was 31.8 ± 6.9 g L-1 with a 62.1 ± 12.8% yield. The immobilized cells allowed eight 10 h sequential reuse cycles to be carried out with stable final ethanol concentrations. In addition, there was no need to use antibiotics and no contamination was observed. After the eighth cycle, there was a significant rupture of the beads making them inappropriate for reuse.
酿酒酵母细胞被固定在海藻酸钙和壳聚糖覆盖的海藻酸钙珠中，并在葡萄糖和蔗糖的发酵中用于生产乙醇。分批发酵在摇床上进行，并通过 HPLC 监测底物和产物的浓度进行评估。细胞固定在海藻酸钙珠和壳聚糖覆盖的海藻酸钙珠中，允许在 8 个 10 小时的连续发酵循环中重复使用珠。使用游离细胞的最终乙醇浓度为 40 g L-1，使用葡萄糖和蔗糖作为碳源的产率分别为 78%和 74.3%。对于固定在海藻酸钙珠中的固定细胞，从葡萄糖中获得的最终乙醇浓度为 32.9±1.7 g L-1，产率为 64.5±3.4%，而从蔗糖中获得的最终乙醇浓度为 33.5±4.6 g L-1，产率为 64.5±8.6%。对于固定在壳聚糖覆盖的海藻酸钙珠中的固定细胞，从葡萄糖中获得的乙醇浓度为 30.7±1.4 g L-1，产率为 61.1±2.8%，而从蔗糖中获得的最终乙醇浓度为 31.8±6.9 g L-1，产率为 62.1±12.8%。固定化细胞允许进行 8 个 10 小时的连续重复使用循环，最终乙醇浓度稳定。此外，无需使用抗生素，也未观察到污染。经过第八个周期后，珠粒出现明显破裂，不适合重复使用。
