Regulatory Mechanisms for Synthesis of Capsular Polysaccharide in Mucoid Mutants of Escherichia Coli K12.

Jacob and Monod have proposed that regulator genes may control the syntheses of several related enzymes in Escherichia coli K12.1 The present paper provides evidence for a regulator gene (designated R1)2 which controls capsular polysaccharide synthesis in E. coli K12. Certain mutants of E. coli produce large mucoid colonies which are characterized by overproduction of polysaccharide. The polysaccharide from such mucoid mutants of E. coli strain W contains galactose, fucose, and uronic acid.3 Serological studies indicated that the capsular material of two mucoid mutants and of the wild type grown at 150C are identical.3 The chemical composition and infrared spectrum of the capsular polysaccharide isolated in the present study are similar to that reported for the polysaccharide isolated from a colicinogenic strain of E. coli (K235).4, 5