tailieunhanh - Advances in Applied Biotechnology Part 4

Tham khảo tài liệu 'advances in applied biotechnology part 4', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Making Green Polymers Even Greener Towards Sustainable Production of Polyhydroxyalkanoates from Agroindustrial By-Products 49 same time. Metabolic Engineering is characterized by a cyclic process involving evaluation of metabolic performance of cells establishment of appropriate target s for genetic engineering and implementation of genetic modification s Nielsen 2001 . The use of analytical tools and metabolic models to study the performance of cells and to identify the appropriate target for genetic modification allows distinguishing Metabolic Engineering from classical genetic engineering and characterize it as a system approach Nielsen Jewett 2008 . PHAs synthesis is an interesting target for Metabolic Engineering manipulation as both polymer assembly and accumulation take place in vivo offering the chance to optimize different metabolic and cellular processes at the same time Jung et al. 2010 Tyo et al. 2010 . The simplest Metabolic Engineering strategy for PHA synthesis manipulation would be to choose the appropriate carbon source s supplied to the bacterial host to control and direct carbon flux through relevant precursors and polymer biosynthesis enzymes. This strategy has traditionally been exploited to modulate polymer composition by varying the feed ratio of different substrate precursors Lutke-Eversloh et al. 2001 Marangoni et al. 2002 . Additionally knowledge of the metabolic network operation under PHA-producing conditions would enable the rational streamlining of catabolic pathways to harness the greatest possible amount of carbon source for polymer synthesis. Knowing the distribution of fluxes is an important way to improve PHA production process towards efficient and sustainable polymer accumulation. Intracellular fluxes are quantitative descriptors which can be used to choose appropriate targets for modification of the metabolic network activity increasing the formation of a desired product . PHAs . In silico genome scale analysis of metabolic