Whole genome-scale transcriptome analysis of enterohemorrhagic Escherichia coil (EHEC) O157:H7 EDL933 was performed to investigate the influence of mucin components on the EHEC gene expression. Here we report that the 732 candidate genes were differentially expressed by the presence of 0.5% porcine stomach mucin, including the 8 flagella-related genes. Quantitative real-time PCR analyses revealed that the transcription expression of the flg genes (encoding the structural components for flagella basal body) was down-regulated by the mucin components. Indeed, bacterial swarming motility was drastically reduced when grown on 0.3% trypton agar plates containing the mucin. These results imply that gastrointestinal (Cl) mucin is a possible environmental signal which negatively regulates the flagellation of EHEC O157:H7 in the Cl tract. (C) 2012 Elsevier Inc. All rights reserved.