title: Metabolic engineering of Escherichia coli for the biosynthesis of alpha-pinene.
abstract: BACKGROUND
  α-Pinene is an important natural product that is widely used in flavorings, fragrances, medicines, fine chemicals and high-density renewable fuels. Currently, α-Pinene used in industry is mainly produced either by tapping trees (gum turpentine) or as a byproduct of paper pulping (crude sulfate turpentine, CST). However, the extraction of it from trees is tedious and inefficient and requires substantial expenditure of natural resources. Therefore, it is necessary to seek sustainable technologies for α-pinene production.
  
  
  RESULTS
  To construct the microbial synthetic pathway of α-pinene in E. coli, we co-expressed native geranyl diphosphate synthase (IspA) from E. coli and α-pinene synthase (Pt30) from Pinus taeda, and then to increase the geranyl diphosphate (GPP) content in the cells, a suitable geranyl diphosphate synthase (GPPS2) was selected from two different origins. Furthermore, to enhance α-pinene production, a novel biosynthetic pathway of α-pinene was assembled in E. coli BL21(DE3) with the heterologous hybrid mevalonate (MVA) pathway, GPPS2 and α-pinene synthase (Pt30). The final genetic strain, YJM28, harboring the above novel biosynthetic pathway of α-pinene, accumulated α-pinene up to 5.44 mg/L and 0.97 g/L under flask and fed-batch fermentation conditions, respectively. The conversion efficiency of glucose to α-pinene (gram to gram) in the metabolically engineered strain reached 2.61%.
  
  
  CONCLUSIONS
  In this paper, by using metabolic engineering techniques, the more efficient biosynthetic pathway of α-pinene was successfully assembled in E. coli BL21(DE3) with the heterologous hybrid MVA pathway, GPPS2 and α-pinene synthase (Pt30). In addition, this is the first report on α-pinene fed-batch fermentation, and our results represent improvements over previous reports.
authors: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. zhanghb@qibebt.ac.cn.
authors: Jianming
authors: J
authors: Yang
authors: Qingjuan
authors: Q
authors: Nie
authors: Meng
authors: M
authors: Ren
authors: Hongru
authors: H
authors: Feng
authors: Xinglin
authors: X
authors: Jiang
authors: Yanning
authors: Y
authors: Zheng
authors: Min
authors: M
authors: Liu
authors: Haibo
authors: H
authors: Zhang
authors: Mo
authors: M
authors: Xian
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