Biosyntehsis and Properties of Copolyesters with 4-Hydroxyalkanoic Acid Unit

本课题研究了含4-羟基链烷酸单元（4 HA）共聚酯的合成及性能。首先利用野生型Ralstonia eutropha H16（现为Wautersia eutropha H16或Cupriviadus necator H16）研究了由3-羟基丁酸（3 HB）和4-羟基丁酸（4 HB）单元组成的共聚酯P（4 HA）的有效生物合成。当R.以4 HB、γ-丁内酯（γ-BL）或ε-己内酯（ε-CL）为4 HB单元供应碳源，在富氮条件下，以丙酸或丁酸为4 HB单元供应碳源，培养真养生物，可有效合成高4 HB组分的P（3 HB-co-4 HB）。此外，由γ-BL和植物油组成的混合碳源的一步摇瓶分批培养导致P（3 HB-co-4 HB）的高生产率。然后，由同一菌株生物合成由3 HB、3-羟基戊酸（3 HV）和4-羟基戊酸（4 HV）组成的三元聚酯和由3 HB、4 HB和3-巯基丙酸（3 MP）组成的三元聚酯。以乙酰丙酸（LA）为可再生碳源，利用野生型R.在L-缬氨酸的存在下从LA中分离真养生物。此外，利用野生型R.真养型。这些含4 HA单元的共聚酯的生物降解性低于P（3 HB-co-4 HB）共聚酯。用模拟体液（SBF）评价了含4 HB单元的共聚酯的生物活性，发现在含4 HB的疏水膜表面成功地形成了磷灰石。

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.