Abstract

Bottlenecks and selective pressures generated by the host shape bacterial populations which in turn react by increasing diversity generating mechanisms including phase variation. Using Streptococcus pneumoniae, a mayor human pathogen, as model we have defined bottlenecks down to a single cell at the beginning of sepsis and identified bacterial genes under very strong selection. Such events reduce diversity and potentially population fitness drastically. On the other hand we found high mutation frequencies in the host and evidence for a phase variable methylation system which significantly impact on bacterial physiology to regain diversity possibly in order to adapt to changing environments. The seminar will try to give an overview on our ongoing research and also address if these investigations are a mere academic exercise or if they could have any potential impact. -Gerlini PLoS Pathogens 2014 -Manso Nature Communications 2014