RUI: Molecular Analysis of PHB/V Biosynthesis

聚b -羟基烷酸酯（PHA）是在许多细菌中发现的聚合物，近年来由于其具有可生物降解的热塑性特性而引起了相当大的兴趣。PHA聚合物的物理性质是由其单体单位中的碳数决定的。例如，聚-羟基丁酸酯（PHB= C4单体单位）更灵活。因此，在PHB/V共聚物的开发方面有大量正在进行的研究。富营养化碱性细菌是最早显示能够产生PHB或PHB/V的细菌之一，这取决于原料。我们的研究小组已将富营养菌中合成聚合物的基因克隆到大肠杆菌中，并利用它们在细胞内产生大量PHB沉积。在使用标准大肠杆菌菌株的初始实验中，即使改变原料以刺激PHB/V合成，我们也无法检测共聚物合成。然而，最近我们能够利用大肠杆菌突变体获得共聚物合成。初步结果表明，大肠杆菌的共聚物合成与富营养化芽孢杆菌相似。本研究的目的是利用新开发的大肠杆菌系统进一步发展我们对PHB/V合成和PHB/V遗传学的认识。这项研究将通过对主要产生PHB和PHB/V的细菌进行全面调查，克隆选定的PHB/V遗传途径，分析能够产生PHV的大肠杆菌中的这些途径，以及利用遗传技术操纵共聚物的合成和结构来完成。

Poly-B-hydroxyalkanoates (PHA's), polymers found in many bacteria, have attracted considerable interest in recent years because they exhibit biodegradable thermoplastic properties. The physical properties of PHA polymers are dictated by the number of carbons in their monomeric unit. For instance, poly-beta-hydroxybutyrate (PHB= C4 monomeric unit) is much more flexible. For this reason, there is considerable ongoing research in the development of the PHB/V copolymer. The bacterium Alcaligenes eutrophus is one of the first bacteria shown to be capable of producing either PHB or PHB/V, depending on the feedstock. The genes for polymer synthesis in A. euthrophus have been cloned into Escherichia coli by our research group where we have employed them to produce large intracellular deposits of PHB. In initial experiments using standard E. coli strains we have not been able to detect copolymer synthesis, even when the feedstock is altered to stimulate PHB/V synthesis. However, recently we were able to obtain copolymer synthesis employing an E. coli mutant. Preliminary results indicate that copolymer synthesis in E. coli is similar to that found in A. eutrophus. The purpose of this research is to further develop our knowledge of PHB/V synthesis and PHB/V genetics using the newly develop E. coli system. This research will be done by conducting a comprehensive survey of bacteria that produce primarily PHB and PHB/V, cloning of selected PHB/V genetic pathways, analysis of these pathways in E. coli capable of PHV production, and manipulation of copolymer synthesis and structure using genetic techniques.