title: Improved phloroglucinol production by metabolically engineered Escherichia coli.
abstract: Phloroglucinol is a valuable chemical which has been successfully produced by metabolically engineered Escherichia coli. However, the low productivity remains a bottleneck for large-scale application and cost-effective production. In the present work, we cloned the key biosynthetic gene, phlD (a type III polyketide synthase), into a bacterial expression vector to produce phloroglucinol in E. coli and developed different strategies to re-engineer the recombinant strain for robust synthesis of phloroglucinol. Overexpression of E. coli marA (multiple antibiotic resistance) gene enhanced phloroglucinol resistance and elevated phloroglucinol production to 0.27 g/g dry cell weight. Augmentation of the intracellular malonyl coenzyme A (malonyl-CoA) level through coordinated expression of four acetyl-CoA carboxylase (ACCase) subunits increased phloroglucinol production to around 0.27 g/g dry cell weight. Furthermore, the coexpression of ACCase and marA caused another marked improvement in phloroglucinol production 0.45 g/g dry cell weight, that is, 3.3-fold to the original strain. Under fed-batch conditions, this finally engineered strain accumulated phloroglucinol up to 3.8 g/L in the culture 12 h after induction, corresponding to a volumetric productivity of 0.32 g/L/h. This result was the highest phloroglucinol production to date and showed promising to make the bioprocess economically feasible.
authors.affiliation: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 266101, Qingdao, China.
authors.forename: Yujin
authors.initials: Y
authors.lastname: Cao
authors.forename: Xinglin
authors.initials: X
authors.lastname: Jiang
authors.forename: Rubing
authors.initials: R
authors.lastname: Zhang
authors.forename: Mo
authors.initials: M
authors.lastname: Xian
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering; D010696:Phloroglucinol / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D010696:Phloroglucinol; D000103:Acetyl-CoA Carboxylase