Some bacterial species live within the human body and its immediate environment, and have various effects on humans, such as causing illness or assisting with digestion, while others colonize a range of other ecological niches. The availability of whole genome sequences for many bacteria opens the way to a better understanding of their metabolism and interactions, provided these genome sequences can be compared. In collaboration with biologists and mathematicians, a bioinformatics team at Montpellier Laboratory of Informatics, Robotics, and Microelectronics (LIRMM) has been developing novel tools to improve bacterial genome comparisons.