β-Lactam induction of colanic acid gene expression in Escherichia coli

• Published in: FEMS microbiology letters 2003-09, Vol.226 (2), p.245-249
• Main Authors: Sailer, Frances C., Meberg, Bernadette M., Young, Kevin D.
• Format: Article
• Language: English
• Subjects: Artificial Gene Fusion; Bacterial Capsules - drug effects; Bacterial Capsules - genetics; Bacterial Capsules - metabolism; Bacteriology; beta-Galactosidase - metabolism; beta-Lactams - metabolism; beta-Lactams - pharmacology; Biofilms - growth & development; Biological and medical sciences; Capsule; Colanic acid; CPS gene; Enzyme Induction; Escherichia coli; Escherichia coli - cytology; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genes, Reporter; Genetics; Lac Operon; lacZ gene; Microbiology; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Penicillin binding protein; Peptidoglycan; Polysaccharides - biosynthesis; Polysaccharides - genetics; β-lactam
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1016/S0378-1097(03)00616-5

An unexpected observation led us to examine the relationship between β-lactam exposure and synthesis of colonic acid capsular polysaccharide in Escherichia coli. Strains containing a cps-lacZ transcriptional fusion were challenged with antibiotics having various modes of action, and gene expression was detected by a disk-diffusion assay and in broth cultures. The cps genes were induced by a subset of β-lactams but not by agents inhibiting protein synthesis or DNA replication, indicating that cps expression was specific and not due to stresses accompanying cell death or by a general inhibition of peptidoglycan synthesis. A narrow concentration just below the MIC triggered cps expression in liquid culture, suggesting the response may be triggered by near-lethal levels of antibiotic. Because colanic acid is important for maturation of biofilm architecture, antibiotics that increase its synthesis might exacerbate the formation or persistence of biofilms.