TABLE 2.

Comparison of mean pixel intensities measured after application of screening techniques 1 and 2 to colonies of the wild type (WT), Mnr mutants 48-4 and 10-10, anaerobic respiratory mutant T121, and 20 randomly selected Mnr-positive strains

Images compared	Strain	Screening technique 1		Screening technique 2		nd
		Pixel intensitya	Normalizedb	Pixel intensityc	Normalizedb
Within one WT colonye	WT	114 ± 2	NAf	204 ± 10	NA	10
Between 50 colonies of a single strain, each on the same plate	WT	114 ± 3	100	201 ± 12	100	50
	T121	12 ± 1	11	10 ± 1	5	50
	48-4	2 ± 0	2	15 ± 1	7	50
	10-10	8 ± 0	7	25 ± 2	12	50
Between 50 colonies of a single strain, each on a separate plate	WT	108 ± 8	100	192 ± 17	100	50
	T121	13 ± 1	12	8 ± 0	4	50
	48-4	2 ± 0	2	17 ± 0	9	50
	10-10	9 ± 0	8	27 ± 2	14	50
Between single colonies of 20 randomly selected Mnr-positive strains on the same plate	NA	113 ± 3	105	199 ± 7	104	20

^aMean pixel intensity ± standard deviation (SD) of 0.40-mm² area (1,394 pixels), except where noted. Total white assigned a value of 256. 

^bMean pixel intensity of indicated strain divided by mean pixel intensity of wild-type strain (reported as a percentage). 

^cMean pixel intensity ± SD of 0.40-mm² area (1,394 pixels), except where noted. Total black assigned a value of 256. 

^dNumber of samples analyzed. 

^eMean pixel intensity of a series of 10 decreasing-size areas demarcated within the wild-type colony shown in either Fig. 3A (screening technique 1) or Fig. 3C (screening technique 2). Demarcated areas were successively decreased in size from 0.40 mm² (1,394 pixels) to 0.04 mm² (139 pixels) every 0.04 mm². 

^fNA, not applicable.