A total of 86% of the B.subtilis genome should be considered as B.subtilis typical (Table 1) . When looking for the origin of B.subtilis segments in the 12 000 signature database, B.subtilis appears in the 10 first potential donors for 84% of the whole set of 5 kb sequences that can be derived from its genome. This result confirms that segments having signatures belonging to the predominant clusters are good representatives of the recipient species signature.