Yewale Tatyaso, Panchwagh Shruti, Rajagopalan Srinivasan, Dhamole Pradip B, Jain Rishi
Praj Matrix R & D Center, Division of Praj Industries Ltd., 402/403/1098, Urawade, Pune, Maharashtra, 412115, India.
Department of Technology, Savitribai Phule Pune University, Ganeshkhind Road, Pune, Maharashtra, 411007, India.
3 Biotech. 2016 Jun;6(1):75. doi: 10.1007/s13205-016-0388-8. Epub 2016 Feb 16.
This study reports an industrially applicable non-sterile xylitol fermentation process to produce xylitol from a low-cost feedstock like corn cob hydrolysate as pentose source without any detoxification. Different immobilization matrices/mediums (alginate, polyvinyl alcohol, agarose gel, polyacrylamide, gelatin, and κ-carrageenan) were studied to immobilize Candida tropicalis NCIM 3123 cells for xylitol production. Amongst this calcium alginate, immobilized cells produced maximum amount of xylitol with titer of 11.1 g/L and yield of 0.34 g/g. Hence, the process for immobilization using calcium alginate beads was optimized using a statistical method with sodium alginate (20, 30 and 40 g/L), calcium chloride (10, 20 and 30 g/L) and number of freezing-thawing cycles (2, 3 and 4) as the parameters. Using optimized conditions (calcium chloride 10 g/L, sodium alginate 20 g/L and 4 number of freezing-thawing cycles) for immobilization, xylitol production increased significantly to 41.0 g/L (4 times the initial production) with corn cob hydrolysate as sole carbon source and urea as minimal nutrient source. Reuse of immobilized biomass showed sustained xylitol production even after five cycles.
本研究报道了一种可工业化应用的非无菌木糖醇发酵工艺，该工艺以玉米芯水解液这种低成本原料作为戊糖来源，无需任何解毒处理即可生产木糖醇。研究了不同的固定化基质/介质（海藻酸钠、聚乙烯醇、琼脂糖凝胶、聚丙烯酰胺、明胶和κ-卡拉胶）来固定热带假丝酵母NCIM 3123细胞以生产木糖醇。其中，海藻酸钙固定化细胞产生的木糖醇量最多，滴度为11.1 g/L，产率为0.34 g/g。因此，以海藻酸钠（20、30和40 g/L）、氯化钙（10、20和30 g/L）以及冻融循环次数（2、3和4）为参数，采用统计方法对海藻酸钙珠固定化工艺进行了优化。在优化的固定化条件（氯化钙10 g/L、海藻酸钠20 g/L和4次冻融循环）下，以玉米芯水解液作为唯一碳源、尿素作为最低营养源时，木糖醇产量显著提高至41.0 g/L（是初始产量的4倍）。固定化生物质的重复使用表明，即使经过五个循环，木糖醇产量仍能持续。
