Carbohydrate accumulation and metabolism in Escherichia coli: I. Description of pleiotropic mutants

Pleiotropic Escherichia coli mutants have been isolated which are defective in their utilization of d-glucose, d-fructose, d-mannose, d-mannitol, d-galactose, maltose, lactose, melibiose, glycerol and succinate. The mutants fail to ferment these carbohydrates, as judged by the color of the colonies on indicator agar plates, and by the failure of the carbohydrates to support growth of the mutants in minimal medium. Some carbohydrates e.g. l-arabinose, pyruvate and glucose-6-phosphate can still be utilized by the mutants, however. Determination of the levels of enzymes in the glycolic pathway and pentose shunt revealed no defect in the enzymes assayed. Uptake experiments with 14C-labeled carbohydrates indicated that the accumulation of the carbohydrates in the mutant cells is affected. Models are discussed to explain the basis of the defect, and the relationships of these mutants to other pleiotropic carbohydrate mutants previously reported are correlated.