Section: New Results

Metabolic network comparison

Previous works on minimal gene sets, when analysing host-dependent bacteria, found small common sets of metabolic genes. When such analyses are restricted to bacteria with similar lifestyles, larger portions of metabolism are expected to be shared and their composition is worth investigating. Comparing the small molecule metabolism of 58 bacteria carefully selected and representing a range of lifestyles, we found not a single enzymatic reaction common to all of them. While obligate intracellular symbionts have no core of reactions within their group, extracellular and cell-associated symbionts do have a small core enriched in biosynthetic processes composed of disconnected fragments. As more genomes are added, we expect, based on our simulations, that the core of cell-associated and extracellular bacteria continues to diminish, converging to approximately 60 reactions. These results were in preparation in 2011 and are now published [17] . The work was done with Ana Tereza Vasconcelos and in a collaboration with Ludovic Cottret (INSA Toulouse).