Fig. 2

Protease expression and secretion in L. plantarum and P. acidilactici. A PepG1 and pro-PepG1 (PepG1 with propeptide) were expressed and secreted in both L. plantarum and P. acidilactici confirmed by western blot analysis. The protein bands corresponded to a molecular mass around 23 kDa, as deduced from positions of molecular weight standards (Bio-Rad; Precision Plus Protein Standards, not shown) and thus corresponded to mature PepG1. The protein bands of pro-PepG1 were visualized at slightly higher position on the gel due to the presence of the 2.6 kDa propeptide. For clarity and conciseness, blots of PepG1 and pro-PepG1 of L. plantarum were cropped from the image of the same gel, while blots of PepG1 and pro-PepG1 of P. acidilactici were cropped from the image of a second gel. The two blots were processed in parallel with the same exposure time (60 s). Full-length blots are presented in Supplementary Fig. S1. Protease activities in supernatants of L. plantarum (B) and P. acidilactici (C) harboring plasmids with different heterologous signal peptides. The white bars represent LP_0373, the control signal peptide chosen in this study. Enzyme activities are expressed in fluorescence intensity units. All results represent the means of three independent experiments; the error bars indicate the standard deviation (SD)