Fig. 6.
Bacterial growth for different inoculation geometries. (A) Inoculation lines of different shapes (on a 1.5% agar gel with 2 g/L peptone nutrient): Ring (O shape), where bacteria grow on the convex edge of the inoculated ring but not on the concave edge, even though the medium has a sufficient nutrient level on the concave side; (for much larger ring diameters, some growth occurs on the concave edge); C shape, where bacteria grow on the convex edge but exhibit little growth on the concave edge; S shape, where, as in the O-and C-shaped inoculations, the bacteria grow on the convex but not the concave edges; note the change in the growth behavior when the curvature changes from convex to concave; and distorted square, where the bacteria grow on the corners but not on either the convex interior edges or on the outer concave edges. (B) The local inhibitor concentration u( r→,t) at the edge of the initial inoculation at the end of the lag time, calculated by the model, is shown by the color bar. The experimental observation is that the colony grows very little in regions where the calculated inhibitor concentration exceeds the level UT.