<p><i>E</i>. <i>coli</i> cells carrying pMccE492 (wt, in yellow) or pJAM434 (poor producing, in green) were transformed with pT5-<i>mceX</i> (driving overexpression of MceX) or pUC57 (control). Antibacterial activity was measured as a function of the growth inhibition halo’s area over a sensitive strain layer, in M9 medium supplemented with IPTG, and was normalized to the value obtained in the control condition for each case. Error bars indicate standard deviation from 40 measurements performed for each condition. **<i>P</i><0.01, ns: not significant.</p