Biotechnology Department, University of São Paulo/Lorena, Campinho Road s/n., P.O. Box: 12600-970, Lorena, São Paulo, Brazil.
Appl Biochem Biotechnol. 2013 Apr;169(7):2101-10. doi: 10.1007/s12010-013-0127-0. Epub 2013 Feb 9.
The present paper studies the biotechnological production of xylitol using sugarcane bagasse hydrolysate in a repeated batch fermentation system with immobilized cells of Candida guilliermondii FTI20037. Immobilized cell system is considered as an attractive alternative to reuse the well-grown and adapted yeast cells in a new fresh fermentation media, without the need of the inoculum stage. In this work, seven repeated batches were performed in a fluidized bed bioreactor using immobilized cells in calcium alginate beads. According to the obtained results it was observed that the immobilized cells of C. guilliermondii can be reused for six successive batches maintaining an average xylitol yield (Y(p/s)) of 0.7 g/L and a volumetric productivity (Q(p)) of 0.42 g/Lh at the end of 432 h of fermentation. On the other hand, in the seventh batch (504 h), a decrease of 44 % in the final concentration of xylitol was observed. This reduction can be explained by the possible diffusion and accumulation of insoluble substances, found in the hemicellulosic hydrolysate, in the interior of the immobilization support resulting in substrate mass transfer limitations.
本论文研究了利用甘蔗渣水解物在固定化 Candida guilliermondii FTI20037 细胞的重复分批发酵系统中生物合成木糖醇。固定化细胞系统被认为是一种有吸引力的选择,可以在新的新鲜发酵培养基中重新使用生长良好和适应的酵母细胞,而无需接种阶段。在这项工作中,在流化床生物反应器中使用海藻酸钙珠中的固定化细胞进行了七次重复分批实验。根据获得的结果,观察到固定化 C. guilliermondii 细胞可以重复使用六次,在 432 小时的发酵结束时保持平均木糖醇产率(Y(p/s))为 0.7 g/L 和体积生产率(Q(p))为 0.42 g/Lh。另一方面,在第七批(504 小时)中,观察到木糖醇的最终浓度下降了 44%。这种减少可以通过可能的扩散和不溶性物质在固定化载体内部的积累来解释,这些物质在半纤维素水解物中发现,导致基质传质限制。