Metris et al. BMC Genomics 2011, 12:535 http://www.biomedcentral.com/1471-2164/12/535 Page 7 of 14 Figure 2 Metabolic genes predicted to be essential or dispensable in silico and in vivo by pathway. The genes predicted to be essential or non essential were determined by FBA (in silico) and from the number of inserts in a transposon mutagenesis of this study (in vivo) in laboratory conditions. Only the genes included in the model reconstruction for FBA are indicated. a) The pie chart shows the distribution of genes belonging to different types of pathway in each category. b) The table indicates the total numbers of genes that fall in each category. predictive approach, we have used random transposon mutagensis coupled to gene-specific PCR to identify those genes that contain one or more transposon insert (dispensable genes for growth under laboratory condi- tions) and those genes that do not contain a transposon insert, the putative essential genes. In silico determination of essential genes Although the reconstruction of the metabolic network of C. jejuni is based on limited biochemical data, it was possible to formulate a hypothesis on the metabolism of this pathogen. The reconstruction pointed out the main areas of uncertainty: the cell wall metabolism and