Transcriptional fusions of Bacillus subtilis DNA to the lacZ gene were screened for induction, initially by ethanol and then by hydrogen peroxide (H2O2). Two fusions were identified which were induced late following treatment with sublethal concentrations of H2O2 (100 microM). The oxy-1 promoter was induced 4-5-fold and mapped to 11 degrees while the oxy-2 promoter was induced 20-fold and mapped close to the right of the defective prophage PBSX, at about 120 degrees. The oxy-2 fusion was induced by mitomycin C as well as H2O2, which correlated with the induction of PBSX by these agents. This was probably not a transcriptional induction, but rather a consequence of the induction of PBSX replication extending into adjacent regions of the chromosome.