Fig. 2

Secretion of recombinant Csn. Mean clear zones diameters (from three colonies of E. coli expressing recombinant Nat-Csn and OmpA-Csn) at 0, 4, 12, 24, and 48 h are shown in the panel a along with standard error. Representative clear zones from different conditions at 4, 12, 24, 48, and 10 days are shown in the panel b. No clear zone was detected around colonies of E. coli expressing empty vector (bottom row). Enlarged picture of the clear zones can be found in Additional file 1: S6