2004-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/707254摘要：生物可分解塑膠生產技術之研發為國際間工業界所注目之環保產品，能減緩現今嚴重之環境污染問題。PHAs (polyhydroxyalkanoates)為細菌於碳源過量時合成用於儲存能量之聚酯類(polyesters)，為生物相容性、微生物可分解性及熱可塑性的重要聚合物材料，目前生產PHAs的方式有利用野生株或變異株、重組菌株發酵生產特用聚酯類。根據目前研究結果顯示短鏈與中鏈PHAs的組合最有利於不同物理性質之生物可分解塑膠的應用。但截至目前為止所發表超過40條PHA synthase基因中僅有一同時具備短鏈與中鏈基質專一性的PHA synthase發表，故本計畫擬利用蛋白質工程技術改良PHA synthase基質專一性以利短鏈與中鏈混合型PHA的生產。本計畫擬分成三年執行，第一年：將短鏈PHA生產菌株Ralstonia eutropha與中鏈PHA生產菌Pseudomonas oleovorans 之PHA synthase基因以PCR方式進行選殖，並構築DNA shuffling基因庫、建立篩選平台及氣相層析儀分析方法，進行基因庫之篩選工作並建立氣相層析儀定量分析系統，將篩選得到的基因送<br> Abstract: The PHAs (polyhydroxyalkanoates) compounds, which are regarded the polyesters of biodegradable plastics have been extensively studied in polymer industries. Thet are also the candidates for alleviating the daily serious problems of environmental pollution caused by undefradable plastic wastes. PHAs, synthesized and stored as the intracellular granules by a wide number of bacteria species, can be accumulated from renewable resources under one essential nutrient such as nitrogen or phosphate limited. The physical characteristics of PHA are similar to PE and possess biodegradable, biocompatible, and thermostable characteristics. Today, biotechnological processes for the fermentative production of polyesters using wild-type bacteria, mutant strains, recombinant bacteria or yeasts have been developed. Further paper reviews suggest that PHA polymers introduced short-chain and medium-chain monomers simultaneously will improve the physical characteristics for multiple applications. However, there are over 40 PA synthase genes cloned and only one possesses broad substrate specificity. This project would be executed through two years and the aims would be focused on (1) Clone the short-chain specific PHB synthase and medium-chain specific PHA synthase from Ralstonia eutropha and Pseudomonas oleovorans, respectively. By way of DNA shuffling approach, a mutant library is constructed, screened by phenotype approach, and verified by gas chromatography for a broad substrate specificity of PHA synthase.生物可分解塑膠PHAs (polyhydroxyalkanoates)biodegradable plasticsPHA synthase gene