Organisms arc provided which express enzymes such as glycerol dehydratase, diol dehydratase, acyl-CoA transferase, acyl-CoA synthetase β-ketothiolase, a;xtoaeetyl-CoA reductase, PHA synthase, glycerol-3-phosphate dehydrogenase and glycerol-3-pbospharase, which are useful for the production of PHAs. In some cases one or more of these genes are native to the host organism and the remainder are provided from transgenes. These organisms produce poJy(3-hydroxyalkanoare) homopolymers or co-polymers incorporating 3-hydroxypropionate or 3-hydroxyvalerate monomers wherein the 3-hydroxynropionate and 3-hydroxyvalreate units are derived from the enzyme catalysed conversion of diols. Suitable diols that can be used include 1,2-propanediol, 1,3-propanediol and glycerol. Biochemical pathways for obtaining the glycerol from normal cellular metabolites are also described. The PHA polymers are readily recovered and industrially useful as polymers or as starting materials for a range of chemical intermediates including 1,3-propanediol, 3-hydroxypropionaldehyde, -acrylics, malonic acid, esters and amines.
所提供的
生物体可表达诸如
甘油脱
水酶、二元醇脱
水酶、酰基-CoA转移酶、酰基-CoA合成酶β-酮
硫醇酶、a;xtoaeetyl-CoA还原酶、PHA合成酶、
甘油-3-
磷酸脱氢酶和
甘油-3-
磷酸酶等酶,这些酶对生产PHA非常有用。在某些情况下,这些
基因中有一个或多个是宿主
生物的原生
基因,其余
基因则由转
基因提供。这些
生物体可生产含有
3-羟基丙酸单体或
3-羟基戊酸单体的 3-羟基烷酸均聚物或共聚物,其中
3-羟基丙酸和
3-羟基戊酸单位来自二元醇在酶催化下的转化。适用的二元醇包括
1,2-丙二醇、
1,3-丙二醇和
甘油。此外,还介绍了从正常细胞代谢物中获取
甘油的生化途径。PHA 聚合物易于回收,在工业上可用作聚合物或一系列
化学中间体(包括
1,3-丙二醇、3-羟基
丙醛、
丙烯酸、
丙二酸、酯和胺)的起始原料。