title: beta-Lactam induction of colanic acid gene expression in Escherichia coli.
abstract: An unexpected observation led us to examine the relationship between beta-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 beta-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.
authors.affiliation: Department of Microbiology and Immunology, University of North Dakota School of Medicine, Grand Forks, ND 58202-9037, USA.
authors.forename: Frances C
authors.initials: FC
authors.lastname: Sailer
authors.forename: Bernadette M
authors.initials: BM
authors.lastname: Meberg
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Young
mesh_terms: D019677:Artificial Gene Fusion; D016667:Bacterial Capsules / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development; D004790:Enzyme Induction; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D007763:Lac Operon; D011134:Polysaccharides / Q000096:biosynthesis* / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism; D047090:beta-Lactams / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011134:Polysaccharides; D047090:beta-Lactams; C004275:colanic acid; D001616:beta-Galactosidase