| 摘要: | 隨著人口增長，塑膠聚合物生產與使用量快速增加，一次性塑膠產品的普及使得塑膠汙染不斷加劇，塑膠污染被全世界公認為長期性的共同問題，聚乳酸 (poly lactic acid, PLA)是一種在全球廣泛使用的可生物降解塑膠材料，被使用後通常作為廢棄物處理，但卻仍有一半以上比例的塑膠廢棄物流佈於自然環境中，已然成為對自然生態系統、人類健康的永久性跨境威脅。PLA由於其單體乳酸可以透過L-乳酸脫氫酶 (L-lactate dehydrogenase, L-LDH)一步轉化為中心代謝物丙酮酸 (胺基酸前體)，因此可將之視為一種低成本的蛋白質合成來源。故本研究建立了一個一鍋法 (one-pot)多酶串聯反應，將L-LA (PLA單體)、CO2和NH4+透過丙酮酸中間體，轉化為四種氨基酸－天門冬胺酸 (Aspartic acid, Asp)、天門冬醯胺 (Asparagine, Asn)、麩胺酸 (Glutamic acid, Glu)及麩醯胺酸 (Glutamine, Gln)，並將其應用至至無細胞蛋白質合成系統 (Cell-free protein synthesis system)。本研究以酵素催化之過程中固定了一個碳以及三個銨，其中，碳的固定成功減少二氧化碳溫室氣體，氨氮可來自於畜牧廢水，此外本研究為內部氧化還原輔因子 (cofactor)再生循環系統，不須額外添加大量且昂貴的輔因子菸鹼醯胺腺嘌呤二核苷酸 (nicotinamide adenine dinucleotide, NAD+ and NADH)，既符合經濟效益且兼顧有效地減少碳排放及氨氮廢水，在解決塑膠廢棄問題的同時，更能夠在可持續發展的框架下推動綠色經濟的進一步增長。;The escalating production and use of plastic polymers due to population growth have exacerbated global plastic pollution, recognized as a persistent and widespread issue. Poly lactic acid (PLA), a commonly used biodegradable plastic, contributes significantly to this problem, with over half of its waste polluting natural environments. To address this, a study focused on PLA′s unique properties, specifically its conversion potential into essential amino acids via NAD+-dependent L-lactate dehydrogenase (L-LDH). Establishing a one-pot multi-enzyme cascade reaction, the study efficiently transformed PLA monomers, CO2, and NH4+ into four amino acids: aspartic acid, asparagine, glutamic acid, and glutamine. Utilizing a cell-free protein synthesis system, this approach offers a sustainable solution to plastic waste management. By incorporating multiple enzyme cascades and an internal redox cofactor regeneration cycle system, the study effectively reduced carbon emissions and ammonium nitrogen wastewater, sourced from livestock farming. This economically viable strategy not only addresses plastic waste but also fosters green economic growth within a sustainable development framework. |
