(Regulation of alcohol fermentation by Escherichia coli). Progress report
Constitutive adhC mutants were used as a starting point for the isolation of further mutants, some of which are defective in alcohol dehydrogenase (ADH) and/or acetaldehyde dehydrogenase (ACDH) activities and some of which are regulatory and express elevated enzyme levels. The structural mutants map close to the adhC gene, suggesting the existence of an anaerobically controlled operon responsible for the conversion of acetyl-CoA to ethanol. Purification of the two enzyme activities indicates that both copurify as a complex of approximately 200,000 daltons. Although confirmation is required, both enzyme activities appear to be functions of a single polypeptide of MW 100,000 daltons. This interpretation is consistent with genetic data which show that most mutants selected directly for loss of either enzyme have also lost the other activity. Temperature sensitive mutants in which both enzymes are thermolabile also support the idea of a single polypeptide for the two activities. Regulatory mutants located away from the adhC locus have been isolated, and result in two to tenfold elevation of both ADH and ACDH. These mutants are in process of further characterization. Study of adh regulation by means of gene fusions has been slowed by technical problems, however we have devised a direct method for the selection of mutants unable to excrete acidic fermentation products and have accumulated a variety of anaerobically regulated gene fusions which have allowed us to estimate that anaerobiosis in E. coli requires the induction of around 50 genes.
- Research Organization:
- Southern Illinois Univ., Carbondale (USA)
- DOE Contract Number:
- AC02-82ER12095
- OSTI ID:
- 5888509
- Report Number(s):
- DOE/ER/12095-1; ON: DE85009726
- Country of Publication:
- United States
- Language:
- English
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14 SOLAR ENERGY
ESCHERICHIA COLI
GENETIC MAPPING
ETHANOL
BIOSYNTHESIS
OXIDOREDUCTASES
PURIFICATION
ANAEROBIC CONDITIONS
ENZYME ACTIVITY
FERMENTATION
GENES
MUTANTS
ALCOHOLS
BACTERIA
BIOCONVERSION
ENZYMES
HYDROXY COMPOUNDS
MAPPING
MICROORGANISMS
ORGANIC COMPOUNDS
SYNTHESIS
550700* - Microbiology
140505 - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)