FIGURE 5: Relevance of antibiotics for the production and secretion of recombinant RBD. (A) Schematic overview and expected mass of the secreted RBD fusion proteins. (B) Western blot analysis with antibodies against the RBD domain (left) and the GST domain (right) of RBD fusion variant 1 in the cell-containing pellet fraction (P) and supernatant fraction (S) following tetracycline induction of the according L. tarentolae liquid cultures containing the indicated amounts of antibiotics. An induced culture without plasmid served as negative control (n.c.) and recombinant RBD as positive control (p.c.). The asterisk labels the TCA precipitate of the 50% supernatant fraction which was lost in the experiment shown. The calculated mass from panel A is indicated. (C) Western blot analysis with antibodies against the HA tag (left), the RBD domain (right), and the His tag (bottom) of RBD fusion variant 2.