Biosyntehsis and Properties of Copolyesters with 4-Hydroxyalkanoic Acid Unit

本课题研究了含4-羟基烷酸单元（4HA）共聚酯的生物合成及其性能。以野生型真菌性Ralstonia eutropha H16（现为wotersia eutropha H16或Cupriviadus necator H16）为原料，研究了由3-羟基丁酸（3HB）和4-羟基丁酸（4HB）组成的共聚酯作为P（4HA）的有效生物合成。在含4HB或γ-丁内酯（γ-BL）或ε-己内酯（ε-CL）为4HB供能碳源的培养基中，在富氮条件下，丙酸或丁酸培养，可有效合成高4HB组分的P（3HB-co-4HB）。此外，通过由y -BL和植物油组成的混合碳源进行一步烧瓶分批培养，P（3HB-co-4HB）的产量很高。然后，用同一菌株合成3HB、3-羟戊酸（3HV）、4-羟戊酸（4HV）和3HB、4HB、3-巯基丙酸（3MP）组成的三聚聚酯。以乙酰丙酸（LA）为可再生碳源有效地制备了P(3HB-co-3HV-co-4HV)s，特别是在l -缬氨酸存在的情况下，野生型富营养酵母以LA为原料合成了4HV分数高于以往报道的三聚酯。此外，以γ-BL和3,3′-硫代二丙酸为原料，利用野生型真菌合成了具有高3MP组分的新型P(3HB-co-4HB-co-3MP)s。这些具有4HA单元的三聚聚酯的生物降解性低于P（3HB-co-4HB）共聚酯。采用模拟体液法（SBF）评价了含4HB单元的共聚酯的生物活性，发现含4HB的共聚酯膜表面成功形成了磷灰石。

The biosynthesis and properties of copolyesters containing 4-hydroxyalkanoic acid unit (4HA) was studied in this research project. The effective biosynthesis of the copolyesters consisting of 3-hydroxybutyric acid(3HB) and 4-hydroxybutyric acid (4HB) units as P(4HA) was investigated at first by using a wild-type Ralstonia eutropha H16 (now, Wautersia eutropha H16 or Cupriviadus necator H16). When R. eutropha was cultivated in medium containing 4HB or γ-butyrolactone (γ-BL) or ε-caprolactone (ε-CL) as 4HB unit-supplying carbon sources and propionic acid or butyric acid in the nitrogen-rich condition, P(3HB-co-4HB) with high 4HB fractions were effectively biosynthesized. Further, one-step flask batch cultivation by the mixed carbon sources consisting of y -BL and plant oils resulted in high productivity of P(3HB-co-4HB). Next, the terpolyesters consisting of 3HB, 3-hydroxyvaleric acid(3HV) and 4-hydroxyvaleric acid(4HV) and consisting of 3HB, 4HB and 3-ruercaptopropionic acid(3MP) were biosynthesized by same strain. P(3HB-co-3HV-co-4HV)s were produced effectively from levulinic acid (LA) as renewable carbon source, and especially, terpolyesters with higher 4HV fraction than that previously reported were biosynthesized by wild-type R. eutropha from LA in the presence of L-valine. Furthermore, novel P(3HB-co-4HB-co-3MP)s with high 3MP fractions were biosynthesized from γ-BL and 3, 3'-thiodipropionic acid by a wild-type R. eutropha. The biodegradabilities of these terpolyesters with 4HA units were lower than those of P(3HB-co-4HB) copolyesters. The bioactivity of the copolyesters with 4HB unit was assessed by using simulated body fluid (SBF) and the apatite was found to be successfully formed on the surface of 4HB-containing copolyester film.