A mutant strain of Escherichia coli K 12 which could not grow on glucose as a sole carbon source was found to have a defect in the transport of glucose. However, this inability of the cells to utilize glucose was found to be restored when the cells were grown on galactose, lactose or D(+)-fucose, a non-metabolizable inducer of the enzymes of galactose metabolism. It was concluded that glucose was transported through the galactose transport system in this mutant cell. When glucose was added to the culture of the cells growing in a mineral galactose medium, the growth of the cells was inhibited. This inhibitory effect of glucose on the growth of the mutant cells growing on galactose was due to the repression of the formation of galactose transport system by glucose which was taken up by the cells through the galactose transport system. It is suggested that diauxie between glucose and galactose may be due to the repression of the formation of galactose transport system and not due to the competitive effects of glucose on the transport of galactose.
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Kamogawa et al. (1967) studied this question.