Kim Tae-Kwon, Jung Young-Mi, Vo Minh Tri, Shioya Suteaki, Lee Yong-Hyun
Department of Genetic Engineering, College of Natural Sciences, Kyungpook National University, Daegu 702-701, S. Korea.
Biotechnol Prog. 2006 Nov-Dec;22(6):1541-6. doi: 10.1021/bp0601746.
Two PHA synthase phaC1 and phaC2 genes cloned from the new strain Pseudomonas putida KCTC1639 were metabolically engineered for the overproduction of medium-chain-length polyhydroxyalkanoate (mcl-PHA). The overexpressed phaC1 and phaC2 genes in P. putida KCTC1639 were compared in terms of the biosynthesis of mcl-PHA, fatty acid assimilation, distribution of 3-hydroxylacyl monomer units, granular morphology, and thermophysical properties of the accumulated mcl-PHA. The biosynthesis of mcl-PHA was enhanced only by the overexpressed phaC1 gene up to 2.86-fold, in contrast, the phaC2 gene did not activate the biosynthesis of mcl-PHA. The overexpressed phaC1 gene tended to form enlarged, high molecular weight, and lower crystalline mcl-PHA granules, whereas the amplified phaC2 gene induced the fragmentation of mcl-PHA into a few small-sized granules. The transformant P. putida KCTC1639 overexpressing the phaC1 gene encoding PHA synthase I was cultivated by pH-stat fed-batch cultivation, and the concentration and content of mcl-PHA increased up to 8.91 g L-1 and 70.5%, respectively.
从新菌株恶臭假单胞菌KCTC1639中克隆出的两个聚羟基脂肪酸酯（PHA）合酶phaC1和phaC2基因，经过代谢工程改造以过量生产中链长度聚羟基脂肪酸酯（mcl-PHA）。对恶臭假单胞菌KCTC1639中过表达的phaC1和phaC2基因在mcl-PHA的生物合成、脂肪酸同化、3-羟基酰基单体单元分布、颗粒形态以及积累的mcl-PHA的热物理性质方面进行了比较。mcl-PHA的生物合成仅通过过表达的phaC1基因增强了2.86倍，相比之下，phaC2基因并未激活mcl-PHA的生物合成。过表达的phaC1基因倾向于形成更大、高分子量且结晶度较低的mcl-PHA颗粒，而扩增的phaC2基因则导致mcl-PHA破碎成一些小尺寸颗粒。通过pH-stat补料分批培养法培养过表达编码PHA合酶I的phaC1基因的恶臭假单胞菌KCTC1639转化体，mcl-PHA的浓度和含量分别增加到8.91 g L-1和70.5%。
