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

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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.