State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, No.30 South Puzhu Road, Pukou District, Nanjing, 211816, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
Bioprocess Biosyst Eng. 2021 Feb;44(2):247-257. doi: 10.1007/s00449-020-02438-x. Epub 2020 Sep 17.
Cell growth and product formation are two critical processes in polysaccharide welan biosynthesis, but the conflict between them is often encountered. In this study, a temperature-dependent strategy was designed for two-stage welan production through overexpressing heat shock proteins in Sphingomonas sp. The first stage was cell growth phase with higher TCA cycle activity at 42 °C; the second stage was welan formation phase with higher precursor synthesis pathway activity at 37 °C. The highest welan concentration 37.5 g/L was achieved after two-stage process. Ultimately, this strategy accumulated welan yield of 79.2 g/100 g glucose and productivity of 0.62 g/L/h at 60 h, which were the best reported results so far. The duration of fermentation was shortened. Besides, rheological behavior of welan gum solutions remained stable at wide range of temperature, pH, and NaCl. These results indicated that this approach efficiently improved welan synthesis.
细胞生长和产物形成是多糖威兰生物合成中的两个关键过程，但它们之间经常存在冲突。在这项研究中，通过在鞘氨醇单胞菌中过表达热休克蛋白，设计了一种用于两阶段威兰生产的温度依赖性策略。第一阶段是细胞生长阶段，在 42°C 时具有更高的三羧酸循环活性；第二阶段是威兰形成阶段，在 37°C 时具有更高的前体合成途径活性。经过两阶段过程，可获得最高浓度的威兰 37.5 g/L。最终，该策略在 60 小时内积累了 79.2 g/100 g 葡萄糖的威兰产率和 0.62 g/L/h 的生产力，这是迄今为止的最佳报道结果。发酵时间缩短。此外，威兰胶溶液在很宽的温度、pH 值和 NaCl 范围内的流变行为保持稳定。这些结果表明，该方法有效地提高了威兰的合成。
