title: Dynamic control of ERG20 expression combined with minimized endogenous downstream metabolism contributes to the improvement of geraniol production in Saccharomyces cerevisiae.
abstract: BACKGROUND
  Microbial production of monoterpenes provides a promising substitute for traditional chemical-based methods, but their production is lagging compared with sesquiterpenes. Geraniol, a valuable monoterpene alcohol, is widely used in cosmetic, perfume, pharmaceutical and it is also a potential gasoline alternative. Previously, we constructed a geraniol production strain by engineering the mevalonate pathway together with the expression of a high-activity geraniol synthase.
  
  
  RESULTS
  In this study, we further improved the geraniol production through reducing the endogenous metabolism of geraniol and controlling the precursor geranyl diphosphate flux distribution. The deletion of OYE2 (encoding an NADPH oxidoreductase) or ATF1 (encoding an alcohol acetyltransferase) both involving endogenous conversion of geraniol to other terpenoids, improved geraniol production by 1.7-fold or 1.6-fold in batch fermentation, respectively. In addition, we found that direct down-regulation of ERG20 expression, the branch point regulating geranyl diphosphate flux, does not improve geraniol production. Therefore, we explored dynamic control of ERG20 expression to redistribute the precursor geranyl diphosphate flux and achieved a 3.4-fold increase in geraniol production after optimizing carbon source feeding. Furthermore, the combination of dynamic control of ERG20 expression and OYE2 deletion in LEU2 prototrophic strain increased geraniol production up to 1.69 g/L with pure ethanol feeding in fed-batch fermentation, which is the highest reported production in engineered yeast.
  
  
  CONCLUSIONS
  An efficient geraniol production platform was established by reducing the endogenous metabolism of geraniol and by controlling the flux distribution of the precursor geranyl diphosphate. The present work also provides a production basis to synthesis geraniol-derived chemicals, such as monoterpene indole alkaloids.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China.
authors.forename: Jianzhi
authors.initials: J
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China. houjin@sdu.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, 250100, China. bxm@sdu.edu.cn.|Shandong Provincial Key Laboratory of Microbial Engineering, School of Bioengineering, QiLu University of Technology, Jinan, 250353, China. bxm@sdu.edu.cn.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bao
mesh_terms: D000080462:Acyclic Monoterpenes; D011756:Diphosphates / Q000378:metabolism*; D004224:Diterpenes / Q000378:metabolism*; D015536:Down-Regulation; D005285:Fermentation; D051228:Geranyltranstransferase / Q000235:genetics* / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods; D039821:Monoterpenes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism*
chemical_list: D000080462:Acyclic Monoterpenes; D011756:Diphosphates; D004224:Diterpenes; D039821:Monoterpenes; D011506:Proteins; D013729:Terpenes; C511282:geranyl diphosphate; D009247:NADH, NADPH Oxidoreductases; C079238:alcohol O-acetyltransferase; D051228:Geranyltranstransferase; C007836:geraniol
keywords: ERG20; Geraniol; Geranyl diphosphate; Monoterpene; Saccharomyces cerevisiae