title: Biosynthesis and characterization of poly(3-hydroxydodecanoate) by β-oxidation inhibited mutant of Pseudomonas entomophila L48.
abstract: A medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) producer Pseudomonas entomophila L48 was investigated for microbial production of 3-hydroxydodecanote homopolymer. Pseudomonas entomophila L48 was found to produce MCL PHA consisting of 3-hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3HO), 3-hydroxydecanoate (3HD), and 3-hydroxydodecanoate (3HDD) from related carbon sources fatty acids. In this study, some of the genes encoding key enzymes in β-oxidation cycle of P. entomophila such as 3-hydroxyacyl-CoA dehydrogenase, 3-ketoacyl-CoA thiolase, and acetyl-CoA acetyltransferase were deleted to study the relationship between β-oxidation and PHA synthesis in P. entomophila. Among the mutants constructed, P. entomophila LAC26 accumulated over 90 wt % PHA consisting of 99 mol % 3HDD. A fed-batch fermentation process carried out in a 6 L automatic fermentor produced 7.3 g L(-1) PHA consisting of over 97 mol % 3HDD fraction. Properties of MCL PHA were significantly improved along with increasing 3HDD contents. P(2.1 mol % 3HD-co-97.9 mol % 3HDD) produced by P. entomophila LAC25 had the widest temperature range between T(g) and T(m), which were -49.3 and 82.4 °C, respectively, in all MCL PHA reported so far. The new type of PHA also represented high crystallinity caused by side-chain crystallization compared with short side chain PHA. For the first time, P(3HDD) homopolymers were obtained.
authors.affiliation: MOE Key Lab of Protein Sciences, Department of Biological Sciences and Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Ah-Leum
authors.initials: AL
authors.lastname: Chung
authors.forename: Hong-Liang
authors.initials: HL
authors.lastname: Jin
authors.forename: Long-Jian
authors.initials: LJ
authors.lastname: Huang
authors.forename: Hai-Mu
authors.initials: HM
authors.lastname: Ye
authors.forename: Jin-Chun
authors.initials: JC
authors.lastname: Chen
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000172:deficiency / Q000235:genetics; D000101:Acetyl-CoA C-Acetyltransferase / Q000172:deficiency / Q000235:genetics; D000102:Acetyl-CoA C-Acyltransferase / Q000172:deficiency / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors; D002849:Chromatography, Gas; D003460:Crystallization; D005227:Fatty Acids / Q000378:metabolism; D005285:Fermentation; D017353:Gene Deletion; D007218:Industrial Microbiology / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D030781:Organisms, Genetically Modified / Q000235:genetics* / Q000254:growth & development; D010084:Oxidation-Reduction; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D011549:Pseudomonas / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; D054813:Polyhydroxyalkanoates; D015094:3-Hydroxyacyl CoA Dehydrogenases; D000102:Acetyl-CoA C-Acyltransferase; D000101:Acetyl-CoA C-Acetyltransferase