Attempt To Gain New Type PHA Materials By Î'-oxidation-disrupted Method And Exploit A PHA Plate In Which Monomer Controllable

Pseudomonas putida KT2442 produces medium-chain-length polyhydroalkanoates consisting of 3-hydroxyhexanoate (3-HHx),3-hydroxyoctanoate (3-HO), 3-hydroxydecanoate (3-HD), and 3-hydroxydodecanoate (3-HDD) from a wide range of carbon sources. In this study, when gene (PP2047 and PP2048) encoding 3-hydroxyacyl-CoA dehydrogenase and gene encoding acyl-CoA dehydrogenase which were might isozyme in step 1 and step 3 ofβoxidation respectively, were completely deleted in Pseudomonas putida KTQQ20, the PHA accumulated was shown to contain only two different monomer structures dominated by a monomer of the same chain length as that of the fatty acids fed and another monomer two carbon atoms shorter, even homopolymer.When C10, C12 and C14 fed as sole carbon source, the accumulated PHA was contained 100%HD,84.26%HDD, and 78.7%HTD respectively. It is grein breakthrought to get such mcl-PHA, expecially homopolymer PHD which was the new type PHA in the world.In the same time, better Thermal and mechanical properties always follows with new construction, the Tm of the P(15.74%HD-HDD) was up to 77.62℃, which was the highest reported of mcl-PHA, and that of homo-PHD also reaches 72.2℃. The Tg and tensile strength of all increases slightly compare to other mcl-PHA. Especially the tensile strength of homo-PHD was up to 12Mp. Thermal and mechanical properties assays indicated that these new type PHA had higher crystallinity and tensile strength than that of typical mcl-PHA.