sodC genes expression in Escherichia coli O157:H7 strains.

INTRODUCTION E. coli O157:H7 has three sodC genes encoding for Cu,Zn superoxide dismutase. We evaluated the expression of chromosomal sodC in distinct phases of growth in different strains, and we examined the mutual capability of chromosomal and prophagic genes to influence their expression. METHODS We used One Step real-time RT-PCR technology to study the expression of sodC genes in several E. coli strains. RESULTS In three of four analysed E. coli O157:H7 strains the chromosomal sodC gene was more expressed in exponential phase than in stationary phase, unlike it occurs in the E. coli K12 strain. The expression of the chromosomal gene was always higher than that of the prophagic copies. Deletion of prophagic or chromosomal sodC genes had no effect on the expression of the residual gene. CONCLUSION Our study highlights an inherent variability in number and level of expression of sodC genes in E. coli O157:H7 strain.