Induction of violacein production in C. violaceum CV026 by N -acylhomoserine lactones and compound 12 (10-4 M). Induction of violacein production was observed by adding different N- acylhomoserine lactones to cultures of C. violaceum CV026. The experiments where conducted according to the well assay described in the methods section. A value of 1 is equal to the violacein production induced by 3.7*10-8 M HHL, 0 = no violacein formed. Values are the mean of 3 determinations, the standard deviation was between 0.01 and 0.09 (error bars indicated).