title: Engineering Halomonas TD01 for the low-cost production of polyhydroxyalkanoates.
abstract: The halophile Halomonas TD01 and its derivatives have been successfully developed as a low-cost platform for the unsterile and continuous production of chemicals. Therefore, to increase the genetic engineering stability of this platform, the DNA restriction/methylation system of Halomonas TD01 was partially inhibited. In addition, a stable and conjugative plasmid pSEVA341 with a high-copy number was constructed to contain a LacI(q)-Ptrc system for the inducible expression of multiple pathway genes. The Halomonas TD01 platform, was further engineered with its 2-methylcitrate synthase and three PHA depolymerases deleted within the chromosome, resulting in the production of the Halomonas TD08 strain. The overexpression of the threonine synthesis pathway and threonine dehydrogenase made the recombinant Halomonas TD08 able to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV consisting of 4-6 mol% 3-hydroxyvalerate or 3 HV, from various carbohydrates as the sole carbon source. The overexpression of the cell division inhibitor MinCD during the cell growth stationary phase in Halomonas TD08 elongated its shape to become at least 1.4-fold longer than its original size, resulting in enhanced PHB accumulation from 69 wt% to 82 wt% in the elongated cells, further promoting gravity-induced cell precipitations that simplify the downstream processing of the biomass. The resulted Halomonas strains contributed to further reducing the PHA production cost.
authors.affiliation: MOE Key Lab of Bioinformatics, National Engineering Laboratory for Anti-tumor Protein Therapeutics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China; Institute of Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Tan
authors.affiliation: MOE Key Lab of Bioinformatics, National Engineering Laboratory for Anti-tumor Protein Therapeutics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.affiliation: MOE Key Lab of Bioinformatics, National Engineering Laboratory for Anti-tumor Protein Therapeutics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Jin-Chun
authors.initials: JC
authors.lastname: Chen
authors.affiliation: MOE Key Lab of Bioinformatics, National Engineering Laboratory for Anti-tumor Protein Therapeutics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China. Electronic address: chengq@mail.tsinghua.edu.cn.
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D003362:Cost-Benefit Analysis; D024861:Genetic Enhancement / Q000379:methods*; D020632:Halomonas / Q000502:physiology*; D060847:Metabolic Engineering / Q000379:methods*; D054813:Polyhydroxyalkanoates / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013912:Threonine / Q000235:genetics* / Q000378:metabolism
chemical_list: D054813:Polyhydroxyalkanoates; D011994:Recombinant Proteins; D013912:Threonine; D000429:Alcohol Oxidoreductases; C023159:L-threonine 3-dehydrogenase
keywords: Cell division inhibitor; Cell elongation; Halomonas; MinCD; PHB; Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Polyhydroxyalkanoates; Threonine synthesis pathway