MOE Key Lab of Protein Sciences, Department of Biological Sciences and Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Biomacromolecules. 2011 Sep 12;12(9):3166-73. doi: 10.1021/bm200660k. Epub 2011 Aug 24.
Polyhydroxyalkanoates (PHA) synthesis genes phbC and orfZ cloned from Ralstonia eutropha H16 were transformed into beta-oxidation weakened Pseudomonas putida KTOY08ΔGC, a mutant of P. putida KT2442. The recombinant P. putida strain termed KTHH06 was able to produce a short-chain-length PHA block copolymer consisting of poly(3-hydroxybutyrate) (P3HB) as one block and poly(4-hydroxybutyrate) (P4HB) as another block. One-dimensional and two-dimensional nuclear magnetic resonance (NMR) clearly indicated the polymer was a diblock copolymer consisting of 20 mol % P3HB as one block and 80 mol % P4HB as another one. Differential scanning calorimetric (DSC) showed that P3HB block melting temperatures (T(m)) in the block copolymer P3HB-b-P4HB was shift to low temperature compared with homopolymer P3HB and a blend of P3HB and P4HB. The block copolymer with a number average molecular weight of 50000 Da and a polydispersity of 3.1 demonstrated a better yield and tensile strength compared with that of its related random copolymer and blend of homopolymers of P3HB and P4HB.
聚羟基烷酸酯（PHA）合成基因 phbC 和 orfZ 从恶臭假单胞菌 H16 中克隆，并转化到β-氧化减弱的恶臭假单胞菌 KTOY08ΔGC，这是恶臭假单胞菌 KT2442 的突变体。重组恶臭假单胞菌菌株称为 KTHH06，能够生产一种由聚（3-羟基丁酸酯）（P3HB）作为一个嵌段和聚（4-羟基丁酸酯）（P4HB）作为另一个嵌段组成的短链长 PHA 嵌段共聚物。一维和二维核磁共振（NMR）清楚地表明，该聚合物是一种由 20mol%的 P3HB 作为一个嵌段和 80mol%的 P4HB 作为另一个嵌段组成的嵌段共聚物。差示扫描量热法（DSC）表明，与均聚物 P3HB 和 P3HB 与 P4HB 的混合物相比，嵌段共聚物 P3HB-b-P4HB 中 P3HB 嵌段的熔融温度（T(m)）向低温移动。数均分子量为 50000Da，多分散性为 3.1 的嵌段共聚物的产率和拉伸强度均优于其相关的无规共聚物和 P3HB 与 P4HB 的均聚物混合物。
