聚羥基烷酯（PHA）是由微生物發酵生產出來的塑膠，有別於現在的石化合成塑膠。PHA具有許多之優點，同時符合「清潔生產」與「環保材料」的要求，因此在國內外引起學術界與工業界廣泛研究。本研究在於建立快速分析方法，以幫助鑑定發酵所生產PHA的種類和結構，再將這些PHA結構資料回饋給合作子計畫主持人，做為修改發酵程序之用。結果發現分析方法中，以核磁共振儀分析方法(1H-NMR及13C-NMR)最為方便及快速，從碳譜中可以立即判斷是否為聚羥基丁酯(PHB)單聚合體或是聚羥基丁酯戊酯(PHBV)共聚合體。而從氫譜中共振吸收峰的面積比值可以推求共聚合體中戊酯單元的比例。經由分析後，得知輔大光合菌2號所生產的PHA為PHBV共聚合體，HV單元的含量為11.6 mol%；光合菌3號所生產的為純PHB。而大同大學所生產的PHA則是PHBV共聚合體，其HV單元的莫耳組成為10.4 mol%。另外從DSC圖中知道，共聚合體的玻璃轉移溫度及熔點都較PHB單聚合體為低，而降低的比例隨著HV單元的增加而增加，熔點的降低有助於增加材料的加工性和韌性。而從相同發酵液，經過不同後續萃取分離方法後，樣品的物性有些許的變化，可見不僅是發酵程序會影響PHA結構、性質，其分離方式亦會影響樣品物性。 Poly(hydroxyalkanoate), PHA, produced from the fermentation of microbial organisms, has many advantages and meets all the requirements of the "environmentally friendly materials" and "green process". Therefore, it has drawn great interest and studies from the academics and industries. Nowadays, three hundred kinds of bacterial have been found that can product PHA and 90 different compositions are identified in the structure unit of PHA. Therefore, it is important to establish a standard procedure to characterize the structures and compositions of PHA. In addition, this would also help understand the metabolism path of bacterial and the relationship between the structures of PHA with the carbon source. Among those analytical methods, nuclear magnetic resonance (NMR) is a very convenient and fast method, not only in the determination of PHA structures, but also its compositions. From the characteristic resonance peaks of various carbons in 13C-NMR spectrum, the structures of PHA are determined immediately. From the area ratio of the proton absorption peak, the molar percentage of HV unit in PHBV copolymer can be determined. After NMR analysis, it is known that the PHA produced from photosynthetic bacteria-3 by Fu-Jen Catholic University is a pure PHB homopolymer. And the PHA from Haloferax mediterranei bacterial by Tatung University is a PHBV copolymer with 10.4 mol% of HV unit. From DSC results, the PHA produced from photosynthetic bacteria-2 is a PHBV copolymer containing 11.6 mol% of HV unit. It is also known from DSC results that the glass transition temperature (Tg) and melting point (Tm) of PHBV decrease as the content of HV unit increases. The decrease of Tm improves the flexibility and toughness of PHA material.
