The outer membrane protein, antigen 43, mediates cell-to-cell interactionswithin Escherichia coli biofilms

Transcription of the agn43 locus, which specifies an outer membrane protein of Escherichia coli, is regulated in a phase-variable fashion by the OxyR- DNA binding protein and Dam methylase. Despite its well-characterized regul ation, the function of Ag43 has remained elusive until now. Previous studie s indicated that Ag43 mediates autoaggregation of certain strains of E. col i in liquid culture. Given this phenotype, we examined the role of Ag43 in biofilm formation. Here, we report that Ag43 contributes to E. coli biofilm formation in glucose-minimal medium, but not in Luria-Bertani broth. In ad dition, we show that flagellar-mediated motility is required for biofilm fo rmation in both rich and minimal environments. Altogether, our results sugg est that E. coli uses both common and specific gene sets for the developmen t of biofilms under various growth conditions.