嗜鹽菌連續醱酵生產高分子PHA及其生產成本之經濟性評估

Polyhydroxyalkanoate Production and Economic Evaluation in the Continuous Fermentation of H. mediterranei

劉建明(Jiam-Ming Liu)

指導教授 ： 陳志成

大同大學/工程學院/生物工程學系所/碩士(2005年)

摘要

極端嗜鹽菌Haloferax mediterranei，能於菌體內累積儲藏性的聚脂 – polyhydroxyalkanoate (PHA)。研究中發現，在重複饋料培養下，以擠壓米糠玉米澱粉和酵母萃取物分別做為碳、氮源饋料，雖可得相當高菌體(110 g/l)與PHA(60 g/gcell)產量，但其成本高且培養過程不穩定，不易控制。所以利用連續式醱酵策略進行培養生產高分子，在稀釋速率為0.03 h-1的連續醱酵中，饋料液以大豆水解液取代酵母萃取物做為氮源培養下，不僅可降低生產成本，且菌體濃度和高分子含量分別可維持連續生產83 g/l和50 %。以此數據進行工廠生產流程設計和經濟評估分析，發現在目前市場所預估之初期生產規模為2800噸/年產量下，PHA之生產成本估計為4.8 US$/kg，而如果以全球量產規模在50000噸/年，則生產成本可預期降至3.74 US$/kg。若與目前昂貴的醫療用生物分解性高分子，如PLA (poly lactic acid)來比較，則PHA在生醫材料市場競爭性具有相當大的潛力。

關鍵字

連續式醱酵 ； 經濟評估 ； 嗜鹽菌 ； 生物可分解性高分子

並列摘要

Haloferax mediterranei, an extreme halophilic archaeon, can accumulate polyhydroxyalkanoate (PHA) as intracellular reserve granules. In the present works, fed-batch fermentation was performed with feeding medium contained extruded rice bran/corn starch and yeast extract (YE) as carbon and nitrogen sources, respectively. Although high cell concentration (110g/l) and PHA content (60% g/gcell) could be obtained, it was difficulty to control and maintain the stable cultivation. In order to reduce the production cost, feeding medium includes soybean hydrolyte (SH) as nitrogen source in place of YE and also a continuous fermentation process at dilution rate of 0.03 was carried out for the production of PHA. The continuous process revealed that cell concentration and PHA content could be maintained at 83 g/l and 50 %, respectively. Based on this result, an industrial scale production processes was designed and subsequently analyzed to estimate the production cost of PHA. According to the local market requirement of 2800 tons per year of PHA, the estimated cost of PHA is about 4.8 US$/kg. Furthermore, base on the global market estimation of 50000 tons per year, the PHA production cost could be lower to 3.74 US$/kg. Compared with the high price of recent medical biodegradable polymers (e.g. Poly lactic acid, PLA), PHA has great potential for the medical biomaterial market.

並列關鍵字

continuous fermentation ； economic evaluation ； Haloferax mediterranei ； polyhydroxyalkanoate

參考文獻

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