One-Pot Microbial Production, Mechanical Properties, and Enzymatic Degradation of Isotactic P[(R)-2-hydroxybutyrate] and Its Copolymer with (R)-Lactate
One-Pot Microbial Production, Mechanical Properties, and Enzymatic Degradation of Isotactic P[(R)-2-hydroxybutyrate] and Its Copolymer with (R)-Lactate
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DOI：
10.1021/bm400278j
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发表时间：
2013-06-01
影响因子：
6.2
通讯作者：
Taguchi, Seiichi
中科院分区：
文献类型：
--
作者：
Matsumoto, Ken'ichiro;Terai, Satsuki;Taguchi, Seiichi
P[（R）-2-羟基丁酸酯] [P（（R）-2HB）]是一种类似于聚乳酸（PLA）的脂肪族聚酯。然而，很少有人知道它的性质，因为高成本的商业可获得的手性2 HB作为起始物质的化学聚合物合成。在这项研究中，P[（R）-2HB]和P[（R）-2 HB-co-（R）-乳酸酯] [P（（R）-2 HB-co-（R）-LA）]与一个新的单体组合，成功地在重组大肠杆菌LS 5218中从较便宜的外消旋2 HB使用R-特异性聚酯合酶合成。表达来自假单胞菌属物种61-3的工程化聚羟基链烷酸酯合酶和来自埃氏巨球菌的丙酰-CoA转移酶的细胞在摇瓶中在含有2 HB和葡萄糖的LB培养基上生长，并积累高达17重量%的P[（R）-2HB]，光学纯度> 99.1%。此外，在罐式发酵罐中培养的相同细胞产生P（86摩尔% 2 HB-co-LA）共聚物。值得注意的是，P（2 HB）（27000）和P（2 HB-co-LA）（39000）的分子量（M-w）比先前通过化学缩聚合成的P（2 HB）高2倍和3倍。P（2 HB）通过溶剂流延法制备成透明薄膜，其断裂伸长率为173%，与刚性PLA相比具有柔性。关于机械性能，P（2 HB-co-LA）比P（2 HB）更坚韧但拉伸性更差。这些结果表明，P（2 HB）具有有用的性能，2 HB基聚合物中的LA单元可以作为材料性能的可控调节剂。此外，P[（R）-2HB]通过Novozym 42044（脂肪酶）而不是Savinase 16 L（蛋白酶）的处理被有效地降解，表明聚合物的降解行为与P[（R）-LA]的降解行为相似。
P[(R)-2-hydroxybutyrate] [P((R)-2HB)] is an aliphatic polyester analogous to poly(lactic acid) (PLA). However, little has been known for its properties because of a high cost of commercially available chiral 2HB as a starting substance for chemical polymer synthesis. In this study, P[(R)-2HB] and P[(R)-2HB-co-(R)-lactate] [P((R)-2HB-co-(R)-LA)] with a new monomer combination were successfully synthesized in recombinant Escherichia coli LS5218 from less-expensive racemic 2HB using an R-specific polyester synthase. The cells expressing an engineered polyhydroxyalkanoate synthase from Pseudomonas sp. 61-3 and propionyl-CoA transferase from Megasphaera elsdenii were grown on LB medium containing 2HB and glucose in a shake flask and accumulated up to 17 wt% of P[(R)-2HB] with optical purity of >99.1%. In addition, the same cells cultured in a jar-fermentor produced P(86 mol% 2HB-co-LA) copolymer. Notably, the molecular weights (M-w) of P(2HB) (27000) and P(2HB-co-LA) (39000) were 2- and 3-fold higher than that of P(2HB) previously synthesized by chemical polycondensation. P(2HB) was processed into a transparent film by solvent-casting and it had flexible properties with elongation at break of 173%, which was contrast to the rigid PLA. Regarding mechanical properties, P(2HB-co-LA) was tougher but less stretchy than P(2HB). These results demonstrated that P(2HB) has useful properties and LA units in 2HB-based polymers can act as a controllable modulator of the material properties. In addition, P[(R)-2HB] was efficiently degraded by treatment of Novozym 42044 (lipase) but not Savinase 16L (protease), indicating that the degrading behavior of the polymer was similar to that of P[(R)-LA].