Putative integrase that is involved in the insertion of the integrative and conjugative element ICEBs1. Required for the excision of ICEBs1 from the donor cell genome and subsequent integration in the recipient cell genome. Appears not to be transferred through the mating pore. Integration of ICEBs1 involves an attachment site in the chromosome, attB, and a site in the circular form of ICEBs1, attICEBs1. Belongs to the 'phage' integrase family.