Effects of spo0A or abrB mutations on expression of pmxA in B. subtilis analyzed by qRT-PCR (A) and the gel electrophoresis image (B). The relative expression ratios of pmxA for the three mutant strains, BSK4-0A, BSK4-0A-rB, and BSK4-rB, to their parent strain, BSK4, were calculated from the real-time PCR efficiencies. The error bars indicate standard errors of the mean (SEM); n = 3 in all RT-PCR analyses; P < 0.05.