Biodegradation of Bacterial Polyentens in Anerobic Conditions and is mechanisms (2002)

分离出几种降解细菌聚酯（PHB）并进行反硝化的细菌。我们试图分离细胞外PHB解聚合酶并克隆其基因，但失败了。当小鱼（金鱼）在PHB存在下饲养时，观察到水中氮化合物的大量减少。这些结果表明，具有phb降解和反硝化能力的细菌在环境中起着重要的作用。另一方面，我们从富营养菌H16中克隆了胞内PHB解聚合酶（phaZl）的基因并鉴定了其产物（PhaZ1）。PhaZ1的氨基酸序列是新的。PhaZ1的分子量为47 Kda。PhaZ1仅存在于PHB包裹体中，可降解人工无定形PHB颗粒，但不能降解结晶PHB颗粒。我们进一步克隆了几个细胞内3-羟基丁酸低聚物水解酶。其中一种胞内3hb -低聚物水解酶（PhaZ2）同时具有3hb -低聚物水解酶和PHB解聚合酶的活性，PhaZ2同时定位于细胞质和PHB内含物中，PhaZ1和PhaZ2的数量随着细胞中PHB含量的增加而增加。缺失phaz1和PhaZ2的零突变体显示PHB在细胞中的沉积增加。这些结果表明，phazz1和PhazZ2共同参与了PHB的细胞内降解

Several bacteria which degrade bacterial polyester (PHB) and also perform denitrification were isolated. We attempted the isolation of extracellular PHB depolymerases and cloning of their genes, but failed. When small fish (gold fish) were kept in the presence of PHB, a considerable reduction of nigrogen compounds in water was observed. These results indicate that the important role of the bacteria with ability of both PHB-degradation and denitrification in environment. On the other hand, we coned the gene of an intracellular PHB depolymerase (phaZl) from Ralstonia eutropha H16 and charaterization its product (PhaZ1). The amino acid sequence of PhaZ1 was novel. The molecular mass of PhaZ1 was 47 Kda. PhaZ1, which localized solely in PHB inclusions, degraded artificial amorphous PHB granules, but not crystalline PHB granules. We further cloned several intracellular 3-hydroxybutyrate-oligomer hydrolases. One of them, an intracellular 3HB-oligomer hydrolase (PhaZ2) from R. eutropha, showed both 3HB-oligomer hydrolase and PHB depolymerase activities, PhaZ2 localizedd both in cytosol and PHB inclusions, The amounts of PhaZ1 and PhaZ2 increased with the content of PHB in cells. The null mutant lacking both PhaZ1and PhaZ2 revealed the increase PHB deposition in cells. These results indicate that PhaZ1 and PhazZ2 cooperate in intracellular degradation of PHB