Mutants of Escherichia coli deficient in the fermentative lactate dehydrogenase

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Journal of Bacteriology; (USA)

OSTI ID:7066980

Mat-Jan, F; Alam, K Y; Clark, D P ^[1]

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1. Southern Illinois Univ., Carbondale (USA)

Mutants of Escherichia coli deficient in the fermentative NAD-linked lactate dehydrogenase (ldh) have been isolated. These mutants showed no growth defects under anaerobic conditions unless present together with a defect in pyruvate formate lyase (pfl). Double mutants (pfl ldh) were unable to grow anaerobically on glucose or other sugars even when supplemented with acetate, whereas pfl mutants can do so. The ldh mutation was found to map at 30.5 min on the E. coli chromosome. The ldh mutant FMJ39 showed no detectable lactate dehydrogenase activity and produced no lactic acid from glucose under anaerobic conditions as estimated by in vivo nuclear magnetic resonance measurements. We also found that in wild-type strains the fermentative lactate dehydrogenase was conjointly induced by anaerobic conditions and an acidic pH. Despite previous findings that phosphate concentrations affect the proportion of lactic acid produced during fermentation, we were unable to find any intrinsic effect of phosphate on lactate dehydrogenase activity, apart from the buffering effect of this ion.

• DOE Contract Number: AC02-82ER12095
• OSTI ID: 7066980
• Journal Information: Journal of Bacteriology; (USA), Vol. 171:1; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ESCHERICHIA COLI
ENZYME ACTIVITY
LACTATE DEHYDROGENASE
ANAEROBIC CONDITIONS
BIOSYNTHESIS
FERMENTATION
LACTIC ACID
MUTANTS
PHOSPHATES
BACTERIA
BIOCONVERSION
CARBOXYLIC ACIDS
ENZYMES
HEMIACETAL DEHYDROGENASES
HYDROXY ACIDS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
SYNTHESIS
550500* - Metabolism