Fig. 2
a Growth curve of the recombinant P. pastoris strain GS115 [pPIC9 K28-mCherryHDEL] during fermentation. The starting point of methanol feeding (K28 expression induction) is marked by an arrow. b Fluorescence development of mCherry-tagged K28. Cell-free culture supernatant samples from different fermentation time points were separated by SDS-PAGE under non-reducing conditions. Fusion proteins were detected by UV illumination. Position and size of the fusion proteins are indicated. c Killer activity of the fermentation product K28-mCherryHDEL. Cell-free culture supernatants were tested against the sensitive S. cerevisiae strain 192.2d in an agar diffusion assay (t0 = starting point of methanol feeding; tend = 120 h post methanol induction). Cell-free zones of growth inhibition were determined and killer activity was compared to a ×200 concentrated culture supernatant of the K28 killer strain S. cerevisiae MS300b