Fig. 8. Resting cells of the A. tumefaciens ΔbioR mutant strain synthesize biotin when supplemented with l-lysine, 2-oxoadipate, or glutarate.

No detectable biotin was synthesized by the ΔbioR strain when acetate, malonate, or pimelate were the supplements. The sectors were divided by plastic walls to prevent cross-feeding and the compound incubated with each resting cell sample and their concentration are given on the Figure. Note that addition of glucose allows the resting cells to resume growth. Resting cells were used to avoid the complication of competing reactions and substrates during growth.