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Title: Carbohydrate utilization in streptomyces coelicolor A3(2)
Author: Hodgson, D. A.
ISNI:       0000 0001 3579 8110
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 1980
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A newly devised method to obtain diffuse growth of Streptomyces coelicolor A3(2) in liquid minimal medium, was used to study glucose repression. Although diaul4c growth was not obtained glucose repression of uptake of C carbon sources was demonstrated. Cellobiose and rhamnose could also cause repression. Active, arabinose induced, arabinose transport was repressed, at the level of transcription,, by glucose. Of two glycerol inducible glycerol transport systems, one was glucose inhibited but not repressed (and operate by facilitated diffusion)., whilst the other (an active transport system) was glucose repressed but not inhibited. Constitutive active transport systems for galactose and fructose were both inhibited by glucose. Galactose and fructose metobilizing enzymes were inducible by the respective sugars, but only in the absence of glucose. This was both because glucose inhibited galactose and fructose transport and because it repressed the metabolic enzymes concerned. Constitutive active glucose uptake was also demonstrated. Glucose repression (and glucose inhibition of transport) was also implied for utilization of several other soluble carbon sources, and demonstrated for several extracellular enzymes and differentiation events. Mutants that grew on arabinose or glycerol in the presence of 2-deoxyglucose were glucose derepressed for both soluble carbon source utilization and extracellular agarase but not for production of those antibiotics tested. Three classes of glucose derepressed mutants were isolated - glucose nonutilizing (probably glucose kinase-less); glucose poorlyutilizing; and glucose utilizing (the latter implying a negative control of glucose repression). A model of glucose repression (involving glucose phosphorylation via a phosphate receptor protein(s)) has been proposed. No clear role for cAMP in glucose repression was demonstrated. Several mutations affecting carbon catabolic pathways were preliminazj% mapped including glycerol sensitive and galactose sensitive mutants; a pleiotropic carbon source non-utilizing mutant; and extracellular agarase mutants. The plasmid SCP1 could apparently integrate into the agarase gene.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Microbiology