In this study, we investigate the relationship between the essentiality of genes and their conservation. Barquist et al. have studied the essentiality of genes in Salmonella Typhi and Salmonella Typhimurium and their results suggested that essential genes are not necessarily conserved and also conserved genes are not necessarily essential in these two serovars (Barquist et al., 2013).
We have studied the essentiality of genes in 12 strains from Enterobacteriaceae family using transposon-directed insertion-site sequencing (TraDIS). This method uses a large-scale transposon mutagenesis approach to generate a population of mutants. The organisms are then left to live in a rich media and after a few minutes, only the fit mutants survive. The positions of remaining insertions can be identified using next-generation sequencing. The genes that are free of insertions are likely to be essential for the survival of the organism. To investigate the conservation of genes, we have developed a protein clustering tool to identify homologous genes within these strains. We are analysing the genes that are conserved between these 12 strains and those that are not and the relationship between their conservation and essentiality.