TABLE 1.

Survival and mutagenesis of spores after treatment with alkylating agents

Strain	Treatment	Survival (%)	% of survivors with the following mutation(s)c:
			aux	spo	aux spo
PS832 (wild type)a	—d	100	<0.5	<0.5	<0.5
	EMS	3	2.9	11.5	4.8
PS356 (α−β−)a	—	65	<0.5	<0.5	<0.5
	EMS	5	9.7	8.7	3.4
PS2318b (recA)a	—	90	<0.5	<0.5	<0.5
	EMS	1	<0.5	<0.5	<0.5
PS2319 (α−β−recA)a	—	95	<0.5	1	<0.5
	EMS	1.2	<0.5	3	<0.5
PS832b	—	30	1	2.9	1.6
	EtO	0.5	7.9	9.2	4.8

^aSpores were incubated in 0.4 M KH₂PO₄ (pH 7.0) with or without 0.45 M EMS. Spores of strains PS832 and PS356 were incubated for 15 h at 30°C, and spores of strains PS2318b and PS2319 were incubated for 2 h at 37°C. In all cases, spores were diluted at least 200-fold into 2.4 ml of 0.1 M Na₂S₂O₃ and then diluted further for analyses of survival on LB medium plates (5, 23). Survivors (at least 200) were picked onto minimal medium or sporulation medium plates to test for the presence of auxotrophic (aux) or sporulation (spo) mutations as described previously (5). 

^bSpores of strain PS832 were treated with or without EtO for 5 min at 55°C and 60% relative humidity in a Joslyn EO Gas Biological Indicator Evaluator Resistometer Vessel (Joslyn Sterilization Corporation, Farmington, N.Y.). 

^cThe values for the percentage of survivors with the indicated mutations in a replicate of these experiments were essentially identical (±20%) to those shown here, and values for spores not treated with EMS were also essentially identical to values reported previously (5, 21). 

^d—, no EMS treatment.