Abstract
Many pathogenic bacterial species show significant intraspecific variations in host preference, ecological fitness and virulence potential to cause human infectious disease. This is exemplified by the species of L. monocytogenes which consists of multiple distinct genetic (or evolutionary) lineages. Some lineages of this species predominantly cause human sporadic and epidemic infections, whereas others have never been implicated in human disease outbreaks for unclear yet intriguing reasons.
We compared 26 L. monocytogenes genomes representing different genetic lineages based on both in silico comparative genomic analysis and high-density DNA microarray hybridizations. We uncovered genes and small regulatory RNAs that likely make L. monocytogenes lineages differ in carbohydrate utilization and stress resistance during their passage through the human gastrointestinal tract. In addition, we identified core genes in the listerial pan-genome that define this species, and assessed the impact of lysogenic bacteriophages on the genomic diversification and evolution.