Integrated Production System of Biodegradable Plastics -Development and Application of Self-disruptive Cells-

构建了两种w -功能细胞类型，PHA生成和自破坏。一种是巨型芽孢杆菌，在Xyl启动子系统的调控下，通过pX载体将解乳芽孢杆菌的裂解基因整合到其染色体上。另一种是大肠杆菌，其负载有双功能质粒，即产PHA基因，产PHA基因和裂解基因。前一种细胞通过生长相关的方式产生PHA，然后在木糖存在的情况下由葡萄糖耗尽诱导细胞裂解。后者在PHA积累到90%的程度后被破坏。在规定的条件下，对两种重组细胞进行了数十次PHA生成和自破坏能力的检测。验证了双细胞功能的有效性，并在罐式发酵罐上进行了产量实验，模拟了工业生产条件。在实验的基础上，通过与传统系统的比较，对PHA生产成本进行了评估，验证了该工艺的有效性。生物可降解塑料的商业化肯定是减少塑料对环境污染的一个项目。然而，关于“生物可降解”塑料的有效性也有一些讨论。因为它们的最终使用者可能会在某种程度上有意识地将它们丢弃在环境中，因此需要考虑回收碳资源等碳资源利用的综合策略，并考虑“环境可降解”的概念。本研究旨在从技术方面降低生物降解塑料的生产成本，这可能对生物降解塑料的下一步开发有效。

Two cell types of W-function, PHA production and self-disrupting, were constructed. One was B. megaterium, to the chromosome of which lysis genes of B. amiloliquefaciens phase had been integrated under the regulation of Xyl promoter system by way of pX vector. The other was E. coli to which a dual functional plasmid, PHA producing gene from R. eutropha and lysis genes from lambda phage, was burden. The former cell produced PHA by a growth associated manner, then the cell lysis was induced by the exhaustion of glucose in the presence of xylose. The latter was disrupted after accumulating PHA to the extent of 90 %.These two kinds of recombinant cells were examined in tens of PHA production and self-disruption ability under the intended conditions. The effectiveness of the intended dual cell functions was confirmed, then the productivity experiments were performed using jar fermentors, stimulating the conditions of industrial production.Based on the experimental results, a cost evaluation for the PHA production by comparing the proposed integrated system with a conventional one, demonstrated the effectiveness of the proposed process.Commercialization of biodegradable plastics is surely one item for decreasing the plastic contamination of the environment. However, there are some discussions about the effectiveness of "biodegradable" plastics. Because the final user of them might show somehow a tendency to discard them in the environment consciously, and a comprehensive strategy for the carbon resources utilization such as recycling carbon resources should be reconsidered by taking the concept of "environmentally degradable" into consideration. The present research aimed to contribute a cost reduction in the production of biodegradable plastics from a technical aspect, which might be effective for the next development of them.