(a) Effect of ethyl acetate extract from different strains on the binding activity of rScgR (lane 1, free probe; lane 2, probe + rScgR; lane 3, probe + rScgR + methanol; lane 4, probe + rScgR + extract from ZJUD9; lane 5, probe + rScgR + extract from ZJUD32; lane 6, probe + rScgR + extract from ZJUD33; lane 7, probe + rScgR + extract from ZJUD34). (b) Complementation of the scgA deletion mutant ZJUD7 by different mutated scgA (ZJUD9, ZJUD7 complemented with wild-type ScgA; ZJUD32, ZJUD7 complemented with ScgA[E90A]; ZJUD33, ZJUD7 complemented with ScgA[D253A]; ZJUD34, ZJUD7 complemented with ScgA[Q256A]).