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Polyhydroxyalkanoate synthesized within the bacterial cells , a class of biodegradable polymers, has a wide range of applications in many fields . Poly ( hydroxy fatty acid ) is generally considered to be divided into three types : short-chain poly - hydroxy fatty acid esters, long chain poly - hydroxy fatty acid ester and short chain and long chain polyhydroxyalkanoate copolymer . Wherein the long chain poly hydroxy fatty acid esters are also copolymers, form of the copolymer there is a limit to its processing . Genetic engineering technology to transform a Pseudomonas putida long chain polyhydroxyalkanoate synthesis pathway, to achieve the purpose of changing the monomer composition . Pseudomonas putida KT2442 can be fatty acid as a carbon source synthesis containing 3 - hydroxyhexanoic acid , 3 - hydroxy - octanoic acid , 3 - hydroxydecanoic acid and 3 - hydroxy - dodecanoic acid , hydroxy fatty acid esters of long chain polyethylene copolymer , when the encoding catalytic in long-chain 3 - hydroxy acyl-coenzyme A to generate 3 - keto acyl-coenzyme A 3 - hydroxy- acyl-coenzyme A dehydrogenase gene is completely knocked out , a genetically engineered bacteria - Pseudomonas putida KT2047A to bitterness . capric acid, lauric acid , respectively, as the carbon source culture Pseudomonas putida KT2047A , resulting in long-chain polyhydroxyalkanoate contains only two monomers , lauric acid as the carbon source , we get the long-chain polyhydroxyalkanoate 3 - hydroxydecanoic acid ratio is 44% , a ratio of 56 % in the 3 - hydroxy - dodecanoic acid . Furthermore, we obtained in the long chain of the chemical properties of the poly- hydroxy fatty acid esters tested , wherein the proportion of P ( 44% 3HD - co- 3HDD ) ( 3 - hydroxy- capric acid is 44% , 3 - hydroxy - dodecanoic acid a ratio of 56%) and the melting temperature of the copolymer , the melting enthalpy , and Young's modulus were 75 ° C and 51 Jg -1 < / SUP > and 2.0 MPa .
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