Growth inhibition of Mycobacterium smegmatis by mycobacteriophage-derived enzymes

• We identified a new enzyme LysB from mycobacteriophage Bxz2.
• Its esterase activity was significantly higher than that of a reported LysB (Ms6).
• Presence of surfactant (Tween 80 or Triton X-100) increased the activity of LysB.
• Phage-derived endolysins can inhibit the growth of mycobacterium.

We report the ability of mycobacteriophage-derived endolysins to inhibit the growth of Mycobacterium smegmatis. We expressed and purified LysB from mycobacteriophage Bxz2 and compared its activity with that of a previously reported LysB from mycobacteriophage Ms6. The esterase activity of Bxz2 LysB with pNP esters was 10-fold higher than that of the previously reported LysB but its lipolytic activity was significantly lower. The presence of surfactant – Tween 80 or Triton X-100 – significantly increased the activity of LysB. Characterization of LysB-treated M. smegmatis cells and LysB-treated purified cell wall by mass spectroscopy confirmed the hydrolytic activity of the enzyme. Both enzymes were equally effective in inhibiting the growth of M. smegmatis, demonstrating their potential as bacteriostatic agents.