title: Production of cinnamic and p-hydroxycinnamic acid from sugar mixtures with engineered Escherichia coli.
abstract: BACKGROUND
  The aromatic compounds cinnamic acid (CA) and p-hydroxycinnamic acid (pHCA) are used as flavoring agents as well as precursors of chemicals. These compounds are present in plants at low concentrations, therefore, complex purification processes are usually required to extract the product. An alternative production method for these aromatic acids is based on the use of microbial strains modified by metabolic engineering. These biotechnological processes are usually based on the use of simple sugars like glucose as a raw material. However, sustainable production processes should preferably be based on the use of waste material such as lignocellulosic hydrolysates.
  
  
  RESULTS
  In this study, E. coli strains with active (W3110) and inactive phosphoenolpyruvate:sugar phosphotransferase system (PTS) (VH33) were engineered for CA and pHCA production by transforming them with plasmids expressing genes encoding phenylalanine/tyrosine ammonia lyase (PAL/TAL) enzymes from Rhodotorula glutinis or Arabidopsis thaliana as well as genes aroGfbr and tktA, encoding a feedback inhibition resistant version of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase and transketolase, respectively. The generated strains were evaluated in cultures with glucose, xylose or arabinose, as well as a simulated lignocellulosic hydrolysate containing a mixture of these three sugars plus acetate. Production of CA was detected in strains expressing PAL/TAL from A. thaliana, whereas both CA and pHCA accumulated in strains expressing the enzyme from R. glutinis. These experiments identified arabinose and W3110 expressing PAL/TAL from A. thaliana, aroGfbr and tktA as the carbon source/strain combination resulting in the best CA specific productivity and titer. To improve pHCA production, a mutant with inactive pheA gene was generated, causing an 8-fold increase in the yield of this aromatic acid from the sugars in a simulated hydrolysate.
  
  
  CONCLUSIONS
  In this study the quantitative contribution of active or inactive PTS as well as expression of PAL/TAL from R. glutinis or A. thaliana were determined for production performance of CA and pHCA when growing on carbon sources derived from lignocellulosic hydrolysates. These data will be a useful resource in efforts towards the development of sustainable technologies for the production of aromatic acids.
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. avargas@ibt.unam.mx.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Vargas-Tah
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. luzma@ibt.unam.mx.
authors.forename: Luz María
authors.initials: LM
authors.lastname: Martínez
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. ginah@ibt.unam.mx.
authors.forename: Georgina
authors.initials: G
authors.lastname: Hernández-Chávez
authors.affiliation: Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. rocha@ibt.unam.mx.
authors.forename: Mario
authors.initials: M
authors.lastname: Rocha
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. alfredo@ibt.unam.mx.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Martínez
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. bolivar@ibt.unam.mx.
authors.forename: Francisco
authors.initials: F
authors.lastname: Bolívar
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos, 62210, México. gosset@ibt.unam.mx.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Gosset
mesh_terms: D010723:3-Deoxy-7-Phosphoheptulonate Synthase / Q000235:genetics / Q000378:metabolism; D000642:Ammonia-Lyases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology; D001089:Arabinose / Q000378:metabolism; D002934:Cinnamates / Q000737:chemistry / Q000378:metabolism*; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D008031:Lignin / Q000737:chemistry / Q000378:metabolism; D060847:Metabolic Engineering; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011422:Propionates; D012248:Rhodotorula / Q000201:enzymology; D014174:Transketolase / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000378:metabolism
chemical_list: D002934:Cinnamates; D003373:Coumaric Acids; D010940:Plant Proteins; D011422:Propionates; C036909:lignocellulose; C029010:cinnamic acid; D008031:Lignin; D014994:Xylose; D001089:Arabinose; D014174:Transketolase; D010723:3-Deoxy-7-Phosphoheptulonate Synthase; D000642:Ammonia-Lyases; C023208:L-tyrosine ammonia-lyase; C495469:p-coumaric acid; D005947:Glucose