Figure 4.

Conditional expression of cdnL shows it is essential. (Top) Schematic for M. xanthus strains conditionally expressing cdnL. (Bottom) Cells grown on CTT plates in the light were streaked on CTT plates ± B₁₂, then incubated at 33°C for 2 days under permissive (plates without B₁₂ incubated in the light) or restrictive (plates with B₁₂ incubated in the dark) conditions. Note the lack of growth of MR1467 under restrictive conditions. The red colour in the light is due to carotenogenesis.