Genetic analysis of the Serratia marcescens N28b O4 antigen gene cluster

The Serratia marcescens N28b wbbL gene complements the rfb-50 mutation of Escherichia coli K-12 derivatives and a wbbL mutant has been found to be damaged in O4-antigen biosynthesis. A recombinant cosmid containing the wbbL gene was examined by subcloning and determination of O-antigen production phenotype in E. coli DH5alpha. Findings revealed that a recombinant plasmid (pSUB6) containing approximately 10 kb of DNA insert is sufficient to induce O4-antigen biosynthesis.