Enhancing Production of Medium-Chain-Length Polyhydroxyalkanoates from Pseudomonas sp. SG4502 by tac Enhancer Insertion

第一作者：	Song, Linxin
英文第一作者：	Song, Linxin
联系作者：	Han, Xuerong
英文联系作者：	Han, Xuerong
发表年度：	2023
卷：	15
摘要：	Pseudomonas sp. SG4502 screened from biodiesel fuel by-products can synthesize medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using glycerol as a substrate. It contains a typical PHA class II synthase gene cluster. This study revealed two genetic engineering methods for improving the mcl-PHA accumulation capacity of Pseudomonas sp. SG4502. One way was to knock out the PHA-depolymerase phaZ gene, the other way was to insert a tac enhancer into the upstream of the phaC1/phaC2 genes. Yields of mcl-PHAs produced from 1% sodium octanoate by +(tac-phaC2) and ?phaZ strains were enhanced by 53.8% and 23.1%, respectively, compared with those produced by the wild-type strain. The increase in mcl-PHA yield from +(tac-phaC2) and ?phaZ was due to the transcriptional level of the phaC2 and phaZ genes, as determined by RT-qPCR (the carbon source was sodium octanoate). 1H-NMR results showed that the synthesized products contained 3-hydroxyoctanoic acid (3HO), 3-hydroxydecanoic acid (3HD) and 3-hydroxydodecanoic acid (3HDD) units, which is consistent with those synthesized by the wild-type strain. The size-exclusion chromatography by GPC of mcl-PHAs from the (?phaZ), +(tac-phaC1) and +(tac-phaC2) strains were 2.67, 2.52 and 2.60, respectively, all of which were lower than that of the wild-type strain (4.56). DSC analysis showed that the melting temperature of mcl-PHAs produced by recombinant strains ranged from 60 degrees C to 65 degrees C, which was lower than that of the wild-type strain. Finally, TG analysis showed that the decomposition temperature of mcl-PHAs synthesized by the (?phaZ), +(tac-phaC1) and +(tac-phaC2) strains was 8.4 degrees C, 14.7 degrees C and 10.1 degrees C higher than that of the wild-type strain, respectively.
刊物名称：	POLYMERS
参与作者：	Song, LX (Song, Linxin) [1] , [2] ; Wang, M (Wang, Ming) [3] ; Yu, DB (Yu, Dengbin) [1] , [2] ; Li, Y (Li, Yu) [1] , [4] ; Yu, HW (Yu, Hongwen) [5] ; Han, XR (Han, Xuerong) [1] , [3]