State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
Appl Microbiol Biotechnol. 2018 Sep;102(18):7837-7847. doi: 10.1007/s00253-018-9190-3. Epub 2018 Jul 11.
A whole-cell (cadaverine-producing strain, Escherichia coli AST3) immobilization method was developed for improving catalytic activity and cadaverine tolerance during cadaverine production. Cell-immobilized beads were prepared by polyvinyl alcohol (PVA) and sodium alginate (SA) based on their advantages in biocatalyst activity recovery and mechanical strength. The following optimal immobilization conditions were established using response surface methodology: 3.62% SA, 4.71% PVA, 4.21% CaCl, calcification, 12 h, and freezing for 16 h at - 80 °C, with a cell concentration of 0.3% (g dry cell weight (DCW) per 100 mL) of immobilized beads. After a 2-h bioconversion, the immobilized beads maintained 85% of their original biocatalyst activity, which was 1.8-fold higher than that of free cells. Furthermore, the effects of cell protectants on immobilized biocatalyst activity were examined by fed-batch bioconversion experiments. The results showed that the addition of polyvinylpyrrolidone (PVP) into the immobilized matrix effectively protected biocatalyst activity, with 95% of the relative activity remaining after the 2-h bioconversion. The performance of PVA-SA-PVP-immobilized E. coli AST3 showed continuous production of cadaverine, with an average cadaverine yield of 29 ± 1 g gDCW h after 12 h, suggesting that this method is capable of industrial scale cadaverine production.
为了提高在尸胺生产过程中的催化活性和尸胺耐受性，开发了一种全细胞（产尸胺菌株，大肠杆菌 AST3）固定化方法。通过聚乙烯醇（PVA）和海藻酸钠（SA）的优势，基于它们在生物催化剂活性回收和机械强度方面的优势，制备了细胞固定化珠。使用响应面法确定了以下最佳固定化条件：3.62%SA、4.71%PVA、4.21%CaCl2、钙化、12 h 和在-80°C 下冷冻 16 h，细胞浓度为 0.3%（每 100 mL 固定化珠干细胞重量（DCW））。经过 2 h 的生物转化，固定化珠保持了 85%的原始生物催化剂活性，是游离细胞的 1.8 倍。此外，通过分批补料生物转化实验研究了细胞保护剂对固定化生物催化剂活性的影响。结果表明，将聚乙烯吡咯烷酮（PVP）添加到固定化基质中可有效保护生物催化剂的活性，在 2 h 的生物转化后，相对活性保留了 95%。PVA-SA-PVP 固定化大肠杆菌 AST3 的性能表现出连续生产尸胺的能力，在 12 h 后，平均尸胺产率为 29 ± 1 g ggDCW h，表明该方法能够进行工业规模的尸胺生产。
