Production of PHAs by Transgenic Plants

The EL eutropha phbB and phbC genes also have been introduced into cotton (Gossypiutn hirsutum) with the liber cells as the target site of expression during early or late liber development stages (John and Keller 1996). The objective was to alter the characteristics of the cotton libers. Although poly(3HB) was present at a low level in the liber (3.4 mg/g of dry liber), it already increased the heat capacity and hence improved the insulation properties of the purified cotton. Future goals for the effort are to improve cotton characteristics such as dyeability, warmth, and wrinkle resistance. 

Genes for poly(3HB) biosynthesis have been introduced into Black Mexican sweet corn (maize, Zea mays) and expressed in cultured cells (Hahn et al. 1997). During a 2-year period in a bioreactor, the introduced phbB and phbC genes were unstable, whereas the thiolase activity was constant. Also, the transformed plant cells grew more slowly than the wild-type cells. The construction of suitable plant species for the production of PHAs in specific cellular locations and at the right time will depend on progress in 

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Metabolic engineering also was performed successfully in eukaryotes including yeast (Leaf et al. 1996) and higher plants (see section O Production of PHAs by Transgenic Plants in this chapter) for the production of PHAs. 

Further copolymerizates can be produced by fermentation with other carbon sources. A long-term objective is the incorporation of the bacterial gene for PHB/PHA production in E. coli bacteria or crop plants (transgenic plants), in order to cultivate these biopolymers in grain crops, potatoes, etc. (regenerating raw materials). 

Singh AK, Mallick N (2008) Enhanced production of SCL-LCL-PHA co-polymer by sludge-isolated Pseudomonas aeruginosa MTCC 7925. Lett Appl Microbiol 46 350-357 Snell KD, Peoples OP (2002) Polyhydroxyalkanoate polymers and their production in transgenic plants. Metab Eng 4 29 0... 

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