The aim of this study was contribute to knowledge over alkalophilic cianobacteryum Arthrospira platensis and their interaction with some associated bacteria growing in their mucilage. Heterotrophic culture medium was designed, in this medium were isolated five bacterial strains associated to single culture of A . platensis . It was measured the 3-indol acetic acid (IAA) production by these bacterial strains. Molecular typing allowed identify these bacterial strains like Exiguobacterium aurantiacum str. DSM 20416, Xanthomonas sp. ML-122, Halomonas sp . Ap-5, Bacillus okhensis str. Kh10-101, Indibacter alkaliphilus, type str. LW1T; all these bacteria are halotolerant, alkalophilic and IAA producer. The findings allow suggest a beneficial interaction between A . platensis and their associated bacteria, maybe as evolutionary strategy of cooperation to grow and develop in hypersaline environments.