TABLE 4.

Competition between the wild-type strain CHA0 and the anr mutant CHA21 (Km^r), with and without complementing plasmid pME3817, in YEA medium^a

Incubation (h)	% Kmr colonies in mixtures of:
	CHA0 and CHA21b	CHA0 and CHA21/pME3817c
0	56	59
1	57	57
15	47	45
24	32	45
36	4	46
48	3	49

^aPairs of competing strains were set up by mixing overnight cultures 1:1 (by volume) and diluting the mixtures 50-fold with fresh YEA medium (60 ml) in 120-ml flasks. Incubation of the tightly closed flasks at 30°C resulted in oxygen-limited stationary-phase cultures (approximately 10⁹ cells/ml) after 10 to 15 h. 

^bMean values of triplicate experiments. 

^cMean values of duplicate experiments.