Identification of laboratory-specific variations of Bacillus subtilis strains used in Japan.

The strain of Bacillus subtilis 168 used in laboratories in Japan was distributed in the 1990s when the sequencing consortium commenced operations. After 20 years of use of B. subtilis 168 in many laboratories, observations of variations in growth phenotypes have been reported. In this study, to uncover laboratory-specific variations of B. subtilis 168 strains in Japan, we re-sequenced 11 B. subtilis 168 strains from nine laboratories and analyzed how their genomes differed. We found that the 168 strains from different laboratories differed by 1-7 variations. These variations might have been caused by differences in storage conditions in the laboratories or differences among colonies of the original stock. Based on our results, researchers ought to understand the genetic differences among wild-type (parental) strains in different laboratories and the reference strain by re-sequencing analysis, and ought to pay more attention to the management of laboratory strains.