A comparison of the wild type (FL2267) and mutB (FL2281) strains showing how they respond differently to diethyl methylmalonate supplementation. A Effects of single batch diethyl methylmalonate supplementation on the wild type strain, FL2267, (experiment SFF05B-09) and B effects on FL2281, the mutB knockout strain (experiment SFF01A-09). Also shown is C, effects of daily 5 mM supplementation of diethyl methylmalonate on the mutB knockout strain FL2281 (experiment SFF11A-09). Top panel, bioassay results (error bars represent standard deviation of the mean); middle panel, TLC results; bottom panel, pH and viscosity at day 5. Abbreviations: ErA or ery, erythromycin A; ErB, ErC, erythromycins B and C; EB, erythronolide B; MEB, 3-O-α-mycarosylerythronolide B; diEMM, diethyl methylmalonate.