Homofermentative production of D-lactic acid from sucrose by a metabolically engineered Escherichia coli.
Escherichia coli W, a sucrose-positive strain, was engineered for the homofermentative production of D-lactic acid through chromosomal deletion of the competing fermentative pathway genes (adhE, frdABCD, pta, pflB, aldA) and the repressor gene (cscR) of the sucrose operon, and metabolic evolution for improved anaerobic cell growth. The resulting strain, HBUT-D, efficiently fermented 100 g sucrose l(-1) into 85 g D-lactic acid l(-1) in 72-84 h in mineral salts medium with a volumetric productivity of ~1 g l(-1) h(-1), a product yield of 85 % and D-lactic acid optical purity of 98.3 %, and with a minor by-product of 4 g acetate l(-1). HBUT-D thus has great potential for production of D-lactic acid using an inexpensive substrate, such as sugar cane and/or beet molasses, which are primarily composed of sucrose.
Key Laboratory of Fermentation Engineering (Ministry of Education), College of Bioengineering, Hubei University of Technology, Wuhan, People's Republic of China. wyzzju@126.com
Yongze
Y
Wang
Tian
T
Tian
Jinfang
J
Zhao
Jinhua
J
Wang
Tao
T
Yan
Liyuan
L
Xu
Zao
Z
Liu
Erin
E
Garza
Andrew
A
Iverson
Ryan
R
Manow
Chris
C
Finan
Shengde
S
Zhou
D018533:Biomass; D001709:Biotechnology; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering / Q000379:methods; D005947:Glucose / Q000378:metabolism; D007536:Isomerism; D019344:Lactic Acid / Q000096:biosynthesis* / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D013395:Sucrose / Q000378:metabolism*
D019344:Lactic Acid; D013395:Sucrose; D005947:Glucose