TABLE 2.

Proportions of bacterial populations exhibiting twitching defects after four consecutive subcultures^a

Strain	Expt 1	Expt 2	Expt 3	Expt 4	Expt 5	Expt 6
PAK	0	0	0	0	0	0
lasI	0.05b,c	0.55c,d	0.24c	0	0.02b,c	0.23d
rhlI	0.63c,d	0.67c,d	0	0.07d	0.12c	0

^aProportion is based on ≈1,000 colonies examined for each experiment.

^bVariants with twitching defect similar to vfr null mutant identified; vfr harbors EQERS deletion.

^cS1-type variants identified.

^dS2-type variants identified.