title: Isoprene production by Escherichia coli through the exogenous mevalonate pathway with reduced formation of fermentation byproducts.
abstract: BACKGROUND
  Isoprene, a volatile C5 hydrocarbon, is an important platform chemical used in the manufacturing of synthetic rubber for tires and various other applications, such as elastomers and adhesives.
  
  
  RESULTS
  In this study, Escherichia coli MG1655 harboring Populus trichocarpa isoprene synthase (PtispS) and the exogenous mevalonate (MVA) pathway produced 80 mg/L isoprene. Codon optimization and optimal expression of the ispS gene via adjustment of the RBS strength and inducer concentration increased isoprene production to 199 and 337 mg/L, respectively. To augment expression of MVA pathway genes, the MVA pathway was cloned on a high-copy plasmid (pBR322 origin) with a strong promoter (Ptrc), which resulted in an additional increase in isoprene production up to 956 mg/L. To reduce the formation of byproducts derived from acetyl-CoA (an initial substrate of the MVA pathway), nine relevant genes were deleted to generate the E. coli AceCo strain (E. coli MG1655 ΔackA-pta, poxB, ldhA, dld, adhE, pps, and atoDA). The AceCo strain harboring the ispS gene and MVA pathway showed enhanced isoprene production of 1832 mg/L in flask culture with reduced accumulation of byproducts.
  
  
  CONCLUSIONS
  We achieved a 23-fold increase in isoprene production by codon optimization of PtispS, augmentation of the MVA pathway, and deletion of genes involved in byproduct formation.
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.|Research Center for Industrial Chemical Biotechnology, KRICT, Ulsan, 44468, South Korea.
authors.forename: Jung-Hun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.
authors.forename: Chonglong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.|Life Science Research Institute, Daewoong Pharmaceutical Corporation, Yongin, South Korea.
authors.forename: Hui-Jung
authors.initials: HJ
authors.lastname: Jang
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.
authors.forename: Myeong-Seok
authors.initials: MS
authors.lastname: Cha
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.
authors.forename: Ju-Eon
authors.initials: JE
authors.lastname: Park
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.
authors.forename: Seon-Yeong
authors.initials: SY
authors.lastname: Jo
authors.affiliation: Industrial Biotechnology Research Center, KRIBB, Daejeon, 305-806, South Korea. choi4162@kribb.re.kr.
authors.forename: Eui-Sung
authors.initials: ES
authors.lastname: Choi
authors.affiliation: Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea. swkim@gnu.ac.kr.
authors.forename: Seon-Won
authors.initials: SW
authors.lastname: Kim
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D002070:Butadienes / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D045782:Hemiterpenes / Q000378:metabolism*; D008798:Mevalonic Acid / Q000378:metabolism*; D010420:Pentanes / Q000378:metabolism*; D032107:Populus / Q000201:enzymology / Q000235:genetics
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D019883:Alkyl and Aryl Transferases; C093854:isoprene synthase; D008798:Mevalonic Acid
keywords: Bioisoprene; Carbon utilization; Escherichia coli; Isoprene synthase; Mevalonate pathway