The 72 kb deletion in 1013-2 included the structural genes for biosynthesis of surfactin, a cyclic lipopeptide with a mild hemolytic activity [34] . To test whether the ''military'' and in vitro passaged strains possessed low-grade hemolytic activity, we streaked these variants on rich agar media containing 5% sheep's blood and looked for hemolysis. To our surprise, all strains exhibited striking variation in their coloration (Figure 2A) , with the 1942, 9372-1 and Detrick-1 isolates considerably darker on blood agar than the other ''military'' and in vitro passaged isolates. In addition, on LB the 1013-2 and 9372-1 isolates appeared white and off-white, respectively. Pigmentation of B. subtilis colonies is associated with production of a melanin-like pigment by the CotA protein, a major component of the spore coat [37] . In addition to the variations in pigmentation, streaks of the 1942 and Detrick-1 isolates were consistently translucent under transillumination ( Figure 2B ). These zones of translucency are suggestive of weak b-hemolysis, which has previously been observed in B. subtilis strains that produce high levels of surfactin [34, 35, 38] . The other strains exhibited either weak a-hemolysis or none at all, with the exception of the strongly hemolytic 49822-1 variant. At least in the ''military'' lineage, the quasi-hemolytic phenotype and darkbrown colony pigmentation correlated with the presence of a wildtype spo0F allele, suggesting that the ability of B. atrophaeus to lyse red blood cells may be regulated in part by spo0F. However this was not universally the case; the BACI051 strain had two discernible variants on SBA (not shown), one of which appeared to have recovered partial hemolytic activity ( Figure 2B ).