Escherichia coli MUTANTS DEFECTIVE IN CHEMOTAXIS TOWARD SPECIFIC CHEMICALS^*

Abstract

Mutants of Escherichia coli K12 have been found which fail to carry out chemotaxis toward certain chemicals only. One mutant exhibits greatly reduced chemotaxis toward L-serine but has no detectable defect either in uptake or in oxidative metabolism of that compound. Another mutant is not attracted to D-galactose and certain related sugars. There is a correlation between the galactose chemotaxis defect and a defect in galactose uptake, perhaps indicating a common component for chemotaxis and uptake systems. The results are discussed in terms of a model for chemotaxis in which attractants are detected by specific “chemoreceptors.”