FIG. 1.

Effect of nutrient concentration on swarm rate. Swarm rates of S. meliloti RMB7201 (○) and FS1 (●) and the ratio of the FS1 swarm rate to the RMB7201 swarm rate (▵) are shown. The two strains were separately spotted into swarm agar containing 0.3% agar and 1/100, 1/40, 1/20, 1/10, or 1/5 strength TY. Swarm colony diameters were measured after 2 days of incubation at 28°C. Each datum point is the average of four replicates from a representative experiment. wt, wild type; Conc., concentration.