Response of E. coli to PHMB Polyhexamethylene biguanide (PHMB) is a cationic surfactant commonly used as a biocide against a wide range of microorganisms in a variety of medical and industrial contexts. PHMB has bacteriostatic or bactericidal effects depending on concentration. Previously its action was thought to be caused by disruption of the outer and inner membranes. Transcriptional and protein profiles were generated for E. coli cells exposed to bacteriostatic levels of PHMB. Genes found to be altered in their expression were associated with outer, periplasmic and inner...