Intergeneric homology of the speC gene encoding biosynthetic ornithine decarboxylase in Escherichia coli

A 32P-labeled fragment of DNA containing the speC gene, which encodes the biosynthetic enzyme ornithine decarboxylase of Escherichia coli, was used as a hybridization probe for homologous sequences in the genomes of gram-negative and gram-positive bacteria. The speC probe detected homologous sequences in the DNA of only four members of the Enterobacteriaceae (Citrobacter freundii, Salmonella typhimurium, Klebsiella pneumoniae, and Enterobacter aerogenes); no homology was detected with the DNA of other representative members of the Enterobacteriaceae and gram-negative and gram-positive bacteria.