Endolysin that degrades the junction between mycolic acid and peptidoglycans in the host cell wall and participates with the holin protein in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the mycolic acid-rich outer membrane. Cleaves the ester linkage joining the mycolic acid-rich outer membrane to arabinogalactan, releasing free mycolic acids. Belongs to the L5likevirus endolysin B protein family.