title: Production of p-hydroxybenzoic acid from p-coumaric acid by Burkholderia glumae BGR1.
abstract: p-Coumaric acid (pCA) is abundant in biomass with low lignin content, such as straw and stubble from rye, wheat, and barley. pCA can be isolated from biomass and used for the synthesis of aromatic hydrocarbons. Here, we report engineering of the natural pathway for conversion of pCA into p-hydroxybenzoic acid (pHBA) to increase the amount of pHBA that accumulates more than 100-fold. Burkholderia glumae strain BGR1 (BGR1) grows efficiently on pCA as a sole carbon source via a CoA-dependent non-β-oxidation pathway. This pathway removes two carbons from pCA as acetyl-CoA yielding p-hydroxybenzaldehyde and subsequently oxidizes it to pHBA. To increase the amount of accumulated pHBA in BGR1, we first deleted two genes encoding enzymes that degrade pHBA in the β-ketoadipate pathway. At 10 mM of pCA, the double deletion mutant BGR1_PB4 (Δphb3hΔbcl) accumulated pHBA with 95% conversion, while the control BGR1 accumulated only with 11.2% conversion. When a packed bed reactor containing immobilized BGR1_PB4 cells was operated at a dilution rate 0.2 h(-1) , the productivity of pHBA was achieved at 9.27 mg/L/h for 134 h. However, in a batch reactor at 20 mM pCA, growth of BGR1_PB4 was strongly inhibited, resulting in a low conversion of 19.3%. To further increase the amount of accumulated pCA, we identified the first enzyme in the pathway, p-hydroxcinnmaoyl-CoA synthetase II (phcs II), as the rate-limiting enzyme. Over expression of phcs II using a Palk promoter in a batch reaction at 20 mM of pCA yielded 99.0% conversion to pHBA, which is the highest concentration of pHBA ever reported using a biological process. Biotechnol. Bioeng. 2016;113: 1493-1503. © 2015 Wiley Periodicals, Inc.
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-7442, South Korea.
authors.forename: Da-Hye
authors.initials: DH
authors.lastname: Jung
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-7442, South Korea.
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-7442, South Korea.
authors.forename: Eunok
authors.initials: E
authors.lastname: Jung
authors.affiliation: Department of Biochemistry, Molecular Biology & Biophysics and The Biotechnology Institute, University of Minnesota, Saint Paul, Minnesota, 55108.
authors.forename: Romas J
authors.initials: RJ
authors.lastname: Kazlauskas
authors.affiliation: Department of Environmental Engineering, College of Engineering, Ajou University, Suwon 443-749, Kyeonggi-do, South Korea. kychoi@ajou.ac.kr.
authors.forename: Kwon-Young
authors.initials: KY
authors.lastname: Choi
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-7442, South Korea. byungkim@snu.ac.kr.|Institute of Bioengineering, Seoul National University, Seoul 151-742, South Korea. byungkim@snu.ac.kr.
authors.forename: Byung-Gee
authors.initials: BG
authors.lastname: Kim
mesh_terms: D019117:Burkholderia / Q000235:genetics / Q000378:metabolism*; D003373:Coumaric Acids / Q000032:analysis / Q000378:metabolism*; D008031:Lignin; D060847:Metabolic Engineering / Q000379:methods*; D009154:Mutation; D010226:Parabens / Q000032:analysis / Q000378:metabolism*; D011422:Propionates
chemical_list: D003373:Coumaric Acids; D010226:Parabens; D011422:Propionates; C036909:lignocellulose; D008031:Lignin; C495469:p-coumaric acid; C038193:4-hydroxybenzoic acid
keywords: Burkholderia glumae BGR1; p-coumaric acid; p-hydroxybenzoic acid