TABLE 4.

Levels of mutations in spores of strain PS3664 prepared with or without DPA^a

Time (h) in sporulation (+/−DPA)b	No. of colonies tested	Mutation(s)			%c
		aux	spo	aux and spo
35 (+DPA)	416	1	0	0	<0.2
8 (−DPA)	290	10	19	8	13
25 (−DPA)	237	18	49	11	33

^aSamples (2 ml) were harvested from cultures of strain PS3664 (sspA sspB sleB spoVF) sporulating at 37°C in liquid with or without DPA. The spores were decoated, germinated with lysozyme at an OD₆₀₀ of 1, and plated on LB medium plates as described in Materials and Methods. Colonies on LB medium plates were picked onto appropriate plates for identification of auxotrophic (aux) or asporogenous (spo) mutants, including colonies that had acquired both auxotrophic and asporogenous mutations (aux and spo).

^bFor the culture sporulated without DPA, the sporulation times are as denoted by the arrows in Fig. 4. For the culture sporulated with DPA, the time is equivalent to hour 35 in Fig. 4.

^cThat is, the percentage of mutants in survivors, was calculated as 100 × (the number of colonies with mutations/the total number of colonies tested).