A 4-kilobase congo red binding plasmid DNA fragment of Shigella dysenteriae 1 suppresses the growth and cell differentiation in Escherichia coli.

A 4-kilobase congo red binding plasmid DNA fragment of pCAT 120 of Shigella dysenteriae 1 was transferred to an Escherichia coli K12 strain by transformation. Transformants were unable to grow in any liquid broth medium. Electron microscopic studies revealed that the transformants grown on tryptic soy agar were associated in clusters after cell division. Normal cell separation among the transformants in comparison with recipient E. coli K12 was only observed when the growth medium was supplemented with sterile culture filtrate of the recipient strain. An unknown factor(s) required for cell separation located on the chromosome was suppressed by a 4-kb congo red binding plasmid DNA (pCAT 120) fragment of S. dysenteriae 1.