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Title 

Homofermentative production of D- or L-lactate in metabolically engineered Escherichia coli RR1

Authors 

Dong Eun ChangHeung Chae JungJoon Shick RheeJae Gu Pan

Publisher 

American Society for Microbiology

Issue Date 

1999

Citation 

Applied and Environmental Microbiology, vol. 65, no. 4, pp. 1384-1389

Keywords 

lactate dehydrogenaselactic acidreduced nicotinamide adenine dinucleotidebacterial metabolismbacterium cultureglycolysislactobacillus caseiEscherichia coliL-Lactate Dehydrogenase

Abstract 

We investigated metabolic engineering of fermentation pathways in Escherichia coli for production of optically pure D- or L-lactate. Several pta mutant strains were examined, and a pta mutant of E. coli RR1 which was deficient in the phosphotransacetylase of the Pta-AckA pathway was found to metabolize glucose to D-lactate and to produce a small amount of succinate by-product under anaerobic conditions. An additional mutation in ppc made the mutant produce D-lactate like a homofermentative lactic acid bacterium. When the pta ppc double mutant was grown to higher biomass concentrations under aerobic conditions before it shifted to the anaerobic phase of D-lactate production, more than 62.2 g of D-lactate per liter was produced in 60 h, and the volumetric productivity was 1.04 g/liter/h. To examine whether the blocked acetate flux could be reoriented to a nonindigenous L-lactate pathway, an L-lactate dehydrogenase gene from Lactobacillus casei was introduced into a pta ldhA strain which lacked phosphotransacetylase and D- lactate dehydrogenase. This recombinant strain was able to metabolize glucose to L-lactate as the major fermentation product, and up to 45 g of L-lactate per liter was produced in 67 h. These results demonstrate that the central fermentation metabolism of E. coli can be reoriented to the production of D- lactate, an indigenous fermentation product, or to the production of L- lactate, a nonindigenous fermentation product.

ISSN 

0099-2240

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2017-04-19


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