Efficient incorporation of galactose into lipopolysaccharide by Escherichia coli K-12 strains with polar galE mutations.

Efficient incorporation of exogenous galactose into lipopolysaccharide was observed in a strain with a galE::Tn10 insertion and a strain with a deletion of galOPE. No incorporation was observed in a strain with a longer (galETK) deletion, indicating that incorporation into the galE mutants was due to a low level of expression of galTK from internal or fortuitous promoters. These galE mutants provided a convenient and specific way to radiolabel lipopolysaccharide.