Aggregate formation. Broth cultures from M. bovis BCG(pAS-MDP1) and M. bovis BCG(pMV261) were diluted to an OD (600 nm) of 0.02 to 0.04 and 200 μl were either directly plated on agar plates (0 min) or plated after having been sonified for 2 min to 20 min. The incubation time after plating was three weeks. Panel (A) shows the colonies and in panel (B) the colony numbers are displayed. The columns in (B) represent the mean of 5 plates with the standard deviation.