title: Bioconversion of methanol to value-added mevalonate by engineered Methylobacterium extorquens AM1 containing an optimized mevalonate pathway.
abstract: Methylotrophic biosynthesis using methanol as a feedstock is a promising and attractive method to solve the over-dependence of the bioindustry on sugar feedstocks derived from grains that are used for food. In this study, we introduced and engineered the mevalonate pathway into Methylobacterium extorquens AM1 to achieve high mevalonate production from methanol, which could be a platform for terpenoid synthesis. We first constructed a natural operon (MVE) harboring the mvaS and mvaE genes from Enterococcus faecalis as well as an artificial operon (MVH) harboring the hmgcs1 gene from Blattella germanica and the tchmgr gene from Trypanosoma cruzi that encoded enzymes with the highest reported activities. We achieved mevalonate titers of 56 and 66 mg/L, respectively, in flask cultivation. Introduction of the phaA gene from Ralstonia eutropha into the operon MVH increased the mevalonate titer to 180 mg/L, 3.2-fold higher than that of the natural operon MVE. Further modification of the expression level of the phaA gene by regulating the strength of the ribosomal binding site resulted in an additional 20 % increase in mevalonate production to 215 mg/L. A fed-batch fermentation of the best-engineered strain yielded a mevalonate titer of 2.22 g/L, which was equivalent to an overall yield and productivity of 28.4 mg mevalonate/g methanol and 7.16 mg/L/h, respectively. The production of mevalonate from methanol, which is the initial, but critical step linking methanol with valuable terpenoids via methylotrophic biosynthesis, represents a proof of concept for pathway engineering in M. extorquens AM1.
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Zhu
authors.affiliation: School of Life Sciences, Qingdao Agriculture University, Qingdao, 266109, China.
authors.forename: Jin-Yu
authors.initials: JY
authors.lastname: Cui
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
authors.forename: Lan-Yu
authors.initials: LY
authors.lastname: Cui
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
authors.forename: Wei-Fan
authors.initials: WF
authors.lastname: Liang
authors.affiliation: School of Life Sciences, Qingdao Agriculture University, Qingdao, 266109, China.
authors.forename: Song
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China. chongzhang@tsinghua.edu.cn.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Xing
mesh_terms: D000818:Animals; D001711:Biotransformation; D020048:Blattellidae / Q000201:enzymology / Q000235:genetics; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D013293:Enterococcus faecalis / Q000201:enzymology / Q000235:genetics; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D000432:Methanol / Q000378:metabolism*; D020601:Methylobacterium extorquens / Q000235:genetics* / Q000378:metabolism*; D008798:Mevalonic Acid / Q000378:metabolism*; D009876:Operon; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000235:genetics
chemical_list: D008798:Mevalonic Acid; D000432:Methanol
keywords: Methanol; Methylobacterium extorquens AM1; Mevalonate pathway; Pathway engineering; Terpenoid synthesis