Abstract：
d-Tagatose is one of the several healthy sweeteners that can be a substitute for sucrose and fructose in our daily life. Whole cell-catalyzed phosphorylation and dephosphorylation previously reported by our group afford a thermodynamic-driven strategy to achieve tagatose production directly from starch with high product yields. Nonetheless, the poor structural stability of cells and difficulty in biocatalyst recycling restrict its practical application. Herein, an efficient and stable semiartificial cell factory (SACF) was developed by constructing an organosilica network (OSN) artificial shell on the cells bearing five thermophilic enzymes to produce tagatose. The OSN artificial shell, the thickness of which can be regulated by changing the tetraethyl silicate concentration, exhibited tunable permeability and superior mechanical strength. In contrast with cells, SACFs showed a relative activity of 99.5% and an extended half-life from 33.3 to 57.8 h. Over 50% of initial activity was retained after 20 reuses. The SACFs can catalyze seven consecutive reactions with tagatose yields of over 40.7% in field applications.
摘要：
d-Tagatose是几种健康甜味剂之一，可以在我们的日常生活中替代蔗糖和果糖。我们小组先前报道的全细胞催化的磷酸化和去磷酸化提供了热力学驱动的策略，以直接从淀粉以高产物收率实现塔格糖生产。尽管如此，电池的结构稳定性差和生物催化剂回收利用的难度限制了其实际应用。在这里，通过在带有五种嗜热酶的细胞上构建有机二氧化硅网络（OSN）人工壳以产生塔格糖，开发了一种有效且稳定的半人工细胞工厂（SACF）。OSN人造外壳，其厚度可以通过改变硅酸四乙酯浓度来调节，表现出可调的渗透率和优越的机械强度。与细胞相比，SACF显示99.5%的相对活性和从33.3到57.8小时的延长的半衰期。在20次重复使用后保留超过50%的初始活性。在现场应用中,SACF可以催化七个连续的反应,塔格糖产率超过40.7%。
