Open AccessEnhanced production of d ‐(−)‐3‐hydroxybutyric acid by recombinant Escherichia coli
Author(s) -
Gao HaiJun,
Wu Qiong,
Chen GuoQiang
Publication year - 2002
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2002.tb11286.x
Subject(s) - escherichia coli , fermentation , plasmid , bacteria , chemistry , extracellular , strain (injury) , biochemistry , microbiology and biotechnology , biology , gene , genetics , anatomy
Wild‐type bacteria including Escherichia coli normally do not produce extracellular d ‐(−)‐3‐hydroxybutyric acid (3HB). To produce extracellular chiral 3HB, a new pathway for synthesis of 3HB was constructed by simultaneous expression of genes of β‐ketothiolase ( phb A), acetoacetyl‐CoA reductase ( phb B), phosphor‐transbutyrylase ( ptb ) and butyrate kinase ( buk ) in E. coli strain DH5α. E. coli DH5α containing any one of the four plasmids pBHR69, pUCAB, p68CM or pKKAB that harbor the phb A and phb B genes produced small amounts of 3HB, ranging from 75 to 400 mg l −1 , while E. coli DH5α harboring p68CMPTK containing genes of phb A, phb B, ptb and buk increased the 3HB concentration to 1.4 g l −1 in shake flasks supplemented with LB broth and 20 g l −1 glucose. 3HB production was further improved to over 2 g l −1 in shake flasks when E. coli DH5α hosted two plasmids simultaneously that separately contained phb A and phb B in one plasmid while ptb and buk in the other. A batch fermentation run in a 5‐l fermenter produced approximately 5 g l −1 3HB after 24 h. A fed‐batch process increased 3HB production to 12 g l −1 after 48 h of fermentation.