The significance of biofilms formation for commensalism and pathogenicity of Escherichia coli

Bacterial life in most natural environments involves surface attachment and biofilm formation. However, the contribution of the biofilm lifestyle in bacteria to their survival and pathogenicity remains poorly understood. This research plan is designed to investigate whether surface-associated growth plays an important role in commensalism and pathogenicity of Escherichia coli. Biofilm formation of a collection of commensal and pathogenic E. coli isolates will be assayed in in vitro biofilm models mimicking physiological conditions in the intestine and the urinary tract. Up to five different isolates will be further characterized by genetic analysis. Transposon mutagenesis in conjunction with a high-throughput screen will determine genetic factors utilized by different E. coli isolates for biofilm formation in vitro. In a parallel approach, I will apply micro-arrays and promoter-probe libraries to analyze global gene expression in E. coli biofilms. Factors induced during biofilm growth will be identified. Green fluorescent protein reporter fusions will be used to determine the temporal and spatial expression of genes required and induced during biofilm development. Finally, I propose to apply an in vivo mouse model to investigate the contribution of the identified pathways to survival and pathogenicity of E. coli in the intestine and the urinary tract. The proposed research will provide insights into the pathogenicity of E. coli and should lead to improved strategies for combating emerging E. coli infections.