Bacillus subtilis, like Escherichia coli, possesses several sets of genes involved in the utilization of beta-glucosides. In E. coli, all these genes are cryptic, including the genes forming the bgl operon, thus leading to a Bgl- phenotype. We screened for B. subtilis chromosomal DNA fragments capable of reverting the Bgl+ phenotype associated with an E. coli hns mutant to the Bgl- wild-type phenotype. One B. subtilis chromosomal fragment having this property was selected. It contained a putative Ribonucleic AntiTerminator binding site (RAT sequence) upstream from the bgl gene. Deletion studies as well as subcloning experiments allowed us to prove that the putative B. subtilis of the E. coli bgl operon. We propose that this repression results from the titration of the BglG antiterminator protein of E. coli bgl operon by our putative B. subtilis bglP RAT sequence. Thus, we report evidence for a new cross interaction between heterologous RAT-antiterminator protein pairs.