A large number of Gram-positive and Gram-negative bacteria have been found to produce the signaling molecule autoinducer two (AI-2), which is used for interspecies communication. In this study, AI-2 activity was for the first time determined in Arthrobacter nicotianae, Brevibacterium linens (BL2). Corynebacterium casei, Microbacterium barkeri, Microbacterium gubbeenense and S. equorum subsp. linens (all isolated from the smear of surface ripened cheeses) using the AI-2 bioluminescence assay. This indicates that AI-2 signaling could take place between bacteria found in the smear of surface ripened cheeses.