Since many years, the ProtMic laboratory has been studying the bacterium Arthrospira Platensis in the context of the Melissa project of the European Space Agency. The proteome study of this cyanobacterium showed that the most abundant protein expressed under standard conditions correspond to a protein of unknown function. In addition, phylogenetic analyzes showed that the gene of this protein is largely conserved in cyanobacteria. This project aims at the functional study of this protein/gene by using different approaches as well “in Silico” as experimetales. In addition, a large scale proteomic study will be performed using a SWATH approach from bacterial samples grown in a large number of different conditions (salt stress, temperature, nutrient, light). In parallel, differential and structural genomic studies will be initiated. Finally, the development and study of a mutant for the gene of interest will also be realized.