The mechanical properties of artificial spider silks are approaching a stage where commercial applications become realistic. However, the yields of recombinant silk proteins that can be used to produce fibers with good mechanical properties are typically very low and many purification and spinning protocols still require the use of urea, hexafluoroisopropanol, and/or methanol. Thus, improved production and spinning methods with a minimal environmental impact are needed. We have previously developed a miniature spider silk protein that is characterized by high solubility in aqueous buffers and spinnability in biomimetic set-ups. In this study, we developed a production protocol that resulted in an expression level of >20 g target protein per liter in an Escherichia coli fed-batch culture, and subsequent purification under native conditions yielded 14.5 g/l. This corresponds to a nearly six-fold increase in expression levels, and a 10-fold increase in yield after purification compared to reports for recombinant spider silk proteins. Biomimetic spinning using only aqueous buffers resulted in fibers with a toughness modulus of 74 MJ/m³, which is the highest reported for biomimetically as-spun artificial silk fibers. Thus, the process described herein represents a milestone for the economic production of biomimetic silk fibers for industrial applications.

人造蜘蛛丝的机械性能正在接近商业应用成为现实的阶段。然而，可用于生产具有良好机械性能的纤维的重组丝蛋白的产量通常非常低，许多纯化和纺丝方案仍然需要使用尿素、六氟异丙醇和/或甲醇。因此，需要对环境影响最小的改进生产和纺丝方法。我们之前开发了一种微型蜘蛛丝蛋白，其特点是在水性缓冲液中具有高溶解性，并且在仿生装置中具有可纺性。在本研究中，我们开发了一种生产方案，可在大肠杆菌中实现 >20 g 目标蛋白/升的表达水平分批补料培养，随后在自然条件下纯化，产量为 14.5 g/l。与重组蜘蛛丝蛋白的报道相比，这相当于表达水平增加了近 6 倍，纯化后产量增加了 10 倍。仅使用水性缓冲液的仿生纺丝产生的纤维具有 74 MJ/m ³的韧性模量，这是据报道的仿生初纺人造丝纤维的最高值。因此，本文所述的方法代表了用于工业应用的仿生丝纤维的经济生产的里程碑。