Figure 1.

In vitro expression of ClyA by engineered S. typhimurium carrying the pBAD-ClyA plasmid

(A) Map of the engineered plasmid pBAD-ClyA. (B) The bioluminescent ΔppGpp Salmonella (SL^lux) strain was transformed with pBAD-ClyA (SL^lux/ClyA). Expression of ClyA (34 kDa) in bacterial culture was analyzed by western blotting with an anti-ClyA antibody without (−) or with (+) induction with 0.2% l-arabinose. (C) After spreading 100 μL of 40% l-arabinose on the sheep blood, the plates were divided into two parts; the left side was streaked with live SL^lux, whereas the right side was streaked with live SL^lux/ClyA. Then, the plates were incubated at 37°C overnight. Engineered SL^lux/ClyA lyses blood cells (left) and produces a clear bioluminescent signal in the corresponding area of hemolysis (right).