Effect of amino sugars on catabolite repression in Escherichia coli.

N-acetylglucosamine was found to be a good repressor source for catabolite repression of the beta-galactosidase system in Escherichia coli. It was found capable of increasing the severity of repression by glucose or gluconate when included in the medium with either of these substrates. N-acetylglucosamine was shown to be assimilated under these conditions, but had no effect on culture growth rates. Its influence on catabolite repression was not altered by growth in the presence of inhibiting levels of penicillin. These findings indicated that catabolite repression may be associated with certain reactions of amino sugar metabolism. A working model has been formulated along these lines and will be used to explore this possible relationship further.