Oprimization of production system for bioplastics by enzyme evolutionary engineering

通过各种代谢工程策略的发展，包括基于外部底物操作的自然产生pha的细菌发酵技术（第一代），随后通过重组基因技术（第二代）得到加强，生物合成聚羟基烷酸酯（PHAs）生物聚酯的生物技术研究已经取得了广泛的进展。最近，“酶进化”正在成为PHA生产的第三代方法。以一系列齐格勒-纳塔催化剂为代表的著名化学催化剂“催化剂进化”的发展，实现了具有理想性能的大分子化学合成的突破。因此，人们可以很容易地接受这样一个概念，即与PHA合成相关的生物催化剂（酶）的分子进化将为我们创造高性能的新型PHA材料提供机会。本课程组于2001年首次报道了PHA生物合成的体外酶进化试验。以下的文献资料，以及我们自己致力于这种新方法的实验结果，都是在短时间内逐渐积累起来的。本研究项目侧重于“酶进化”在PHA生物合成中的应用的概念和目前的案例研究。

Biotechnological studies for biosynthesis of polyhydroxyalkanoates (PHAs) biopolyester have been extensively progressed through the development of various metabolic engineering strategies involving fermentation technology of naturally occurring PHA-producing bacteria based on external substrate manipulation (1st generation), subsequently reinforced with recombinant gene technology (2nd generation). Most recently, "enzyme evolution" is becoming the 3rd generation approach for PHA production. Break-through in chemical synthesis of macromolecules with desirable properties was achieved by development of prominent chemical catalysts, "catalyst evolution", as represented by a series of Zigler-Natta catalysts. Thus, one can easily accept the concept that molecular evolution of the biocatalysts (enzymes) relevant to PHA synthesis will provide us a chance to create novel PHA materials with high-performance. The first trial of the in vitro enzyme evolution in PHA biosynthesis was reported by our group in 2001. The following literature data as well as our own experimental results devoted to this new approach have been gradually accumulated for a short time.This research project focused specifically on the concept and current case studies of the application of "enzyme evolution" to PHA biosynthesis.