Existing methods of Mycobacterium avium subsp. paratuberculosis (Map) detection require at least seven weeks to obtain visible growth on solid media. Molecular identification methods are available but are unable to identify the bacterium as live or dead. Mycobacteria specific luciferase reporter phage were utilized to develop an assay for identification of Map. Assay conditions were optimized and inhibitors were identified. Of the phage phAE39, phAE40 and phAE85 tested, phAE85 consistently produced the brightest luminescence in Map and was chosen for use in the assay. Phage phAE85 was capable of infecting all of the 18 Map strains tested. Results indicated that the brightest luminescence was produced with phAE85 at an MOI = 100. Substrate buffer composition was examined and the optimal buffer was chosen. Under optimized conditions the minimum detection limit of the assay is 100 cells. Serum components and detergents were found to inhibit phage binding. The use of IMS beads in the LRP assay will also be discussed.