Fig. 6
Detection of active nisin in SN of C. glutamicum CR099/pXMJ-nisZBTCCg or concentrated RP peak fractions activated with sNisP-His6. A RFU/OD of L. lactis NZ9000/pNZ-Pnis-mcherryLl grown o/N in the presence of supernatants (SN) of C. glutamicum CR099/pXMJ-nisZBTCCg or nisin (0.5 or 1 ng/ml). Prior to assays, supernatants were activated by incubation with the sNisP-His6 preparation shown in Fig. 5B for 3.5 h (sNisP) and diluted 1:2500. B Inhibition of growth (OD600) of L. lactis IL1403 by serial twofold dilutions concentrated RP peak fraction (RPC) or nisin Z (starting concentration of the standard solution 250 µg/ml). Where indicated, the RP peak fraction was activated with either trypsin (0.5 mg/ml) or sNisP-His6 for 3.5 h. All values are mean ± SD of n = 3 independent cultures. As negative controls untreated SN or RP were included. The broken red and green lines indicate OD600 of the positive (i.e. complete inhibition of growth) or negative (i.e. sterile medium) controls, respectively. C Mass spectrometry of sNisP-activated SN analysed in (A, B). The peak corresponding to mature, active nisin Z are highlighted with a red box