Abstract
Cobaltous ions extended the duration of the diauxic lag in Escherichia coli K-12. Growth in glucose in the presence of Co++ was necessary for the effect. Medium in which cells had been grown in the presence of Co++ produced an extended lag when inoculated with fresh cells and lactose. Valine was found in this medium. Reversal of the extended lag was brought about by addition of l-isoleucine and related l-amino acids, but not by several metal ions. Cobaltous ion does not inhibit β-galactosidase or the galactoside permease. These results, together with the known growth sensitivity of K-12 to valine, indicate that Co++ disturbs the normal valine-isoleucine balance.
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Selected References
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