The Biofilm Inhibitor Carolacton Enters Gram-Negative Cells: Studies Using a TolC-Deficient Strain of .

The myxobacterial secondary metabolite carolacton inhibits growth of and kills biofilm cells of the caries- and endocarditis-associated pathogen at nanomolar concentrations. Here, we studied the response to carolacton of an strain that lacked the outer membrane protein TolC. Whole-genome sequencing of the laboratory strain TolC revealed the integration of an insertion element, IS, at the locus and a close phylogenetic relationship to the ancient K-12.