Translation, the decoding process of a messenger RNA molecule (mRNA) into protein, is a fundamental process to life. Errors or mistranslation during mRNA translation can lead to an alteration of the nature and levels of functional proteins which can result in disease. Factors known to control mRNA translation efficiency include amino acid identity, codon choice, the nature and availability of the tRNA species, the differences in ribosomal proteins between species, tRNA modifications and codon context. We will study factors that contribute to the fidelity of translation and the role tRNA and especially the role of tRNA modifications in translation, using an elaborated genetic system in Salmonella.