CONSTITUTIVE GLUCOSE-6-PHOSPHATE DEHYDROGENASE IN MUTANTS UTILIZING GLUCOSE, WHICH ARE DERIVED FROM CRYPTIC WILDTYPE STRAINS

Wildtype cells of Hydrogenomonas H 16 and of similar strains of Hydrogenomonas utilize only fructose; they are unable to use glucose as a carbon source. Mutants were isolated which are able to grow on glucose. Ten of these mutants were investigated and found to be similar with regard to the following properties: 1. they are constitutively derepressed for the formation of glucose-6-phosphate dehydrogenase, 2. the substrate saturation curve of the respiration of glucose is unlike of the fructose curve. While the respiratory rate with fructose as a substrate is already maximal at 1.66 mM fructose, the respiratory rate for glucose as a substrate (at 1.66 mM) amounts only to 15 to 55% of the maximal rate (substrate saturation). The relationships between these pleiotropic effects (glucose utilization and constitutive glucose-6-phosphate dehydrogenase) are unknown. © 1969 Springer-Verlag.