title: Optimal production of poly-gamma-glutamic acid by metabolically engineered Escherichia coli.
abstract: Metabolically-engineered Escherichia coli strains were developed by cloning poly-gamma-glutamic acid (gamma-PGA) biosynthesis genes, consisting of pgsB, pgsC and pgsA, from Bacillus subtilis The metabolic and regulatory pathways of gamma-PGA biosynthesis in E. coli were analyzed by DNA microarray. The inducible trc promoter and a constitutive promoter (P(HCE)) derived from the D-amino acid aminotransferase (D-AAT) gene of Geobacillus toebii were employed. The constitutive HCE promoter was more efficient than inducible trc promoter for the expression of gamma-PGA biosynthesis genes. DNA microarray analysis showed that the expression levels of several NtrC family genes, glnA, glnK, glnG, yhdX, yhdY, yhdZ, amtB, nac, argT and cbl were up-regulated and sucA, B, C, D genes were down-regulated. When (NH(4))(2)SO(4 )was added at 40 g/l into the feeding solution, the final gamma-PGA concentration reached 3.7 g/l in the fed-batch culture of recombinant E. coli/pCOpgs.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, National Engineering Research Centre of Microbial Pesticides, Huazhong Agricultural University, Wuhan 430070, P.R. China. yz41@public.wh.hb.cn
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Longan
authors.initials: L
authors.lastname: Shang
authors.forename: Sung H
authors.initials: SH
authors.lastname: Yoon
authors.forename: Sang Y
authors.initials: SY
authors.lastname: Lee
authors.forename: Ziniu
authors.initials: Z
authors.lastname: Yu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D001709:Biotechnology / Q000379:methods*; D017931:DNA Primers / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005822:Genetic Vectors; D008957:Models, Genetic; D009584:Nitrogen / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010957:Plasmids / Q000378:metabolism; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D009584:Nitrogen