These results indicate that members of group B are subject to a higher rate of recombination than group A. We could hypothesise that the clonal structure of subgroup A was due to lack of natural genetic competence as described for DSM13 (isogenic to ATCC14580) [53, 54]. Surprisingly, the genetically competent strain NVH1082/9945A [55] had identical ST (ST1) to the non-competent type strain ATCC14580, a fact that undermines our hypothesis. Figure

2 MST (Minimum Spanning Tree) analysis. The network was generated in Bionumerics v. 6.6 (Applied Maths) using character data in default mode. Each circle represents a ST and the type number is indicated next to the circle. The areal of the Bafilomycin A1 clinical trial circle corresponds to the number of Cytoskeletal Signaling inhibitor strains represented by each ST. Thick solid lines connect STs that differ at only one locus. Thin, solid lines connect STs that differ at two loci. JNJ-26481585 Dotted lines connect STs that differs at three loci. The distances (in terms of number of locus variants) are also indicated next to the branches. STs of group

A are coloured green while STs of group B are coloured red. In cases were recombination is rare it is generally recommended to concatenate the sequences before calculating dendograms [56]. This concatenated dendogram corresponded well with the allel-based dendogram and is presented in Additional file 3. A small difference between the allel-based and the Alanine-glyoxylate transaminase concatenated dendogram was observed. NVH1032 (ST8) was positioned slightly closer to group A isolates in the latter. When examining individual loci, NVH1032 (ST8) clustered together with group A for all loci apart from adk. It is therefore reasonable to assume that NVH1032 (ST8) could be regarded as a group A member. However, none of the MLST allels of NVH1032 was shared by any other strains in our collection (Additional file 2) underpinning the genetic distinction of NVH1032 (ST8) from the other strains. Conclusions A robust and portable typing scheme for B. licheniformis was established. This method, based on six

house-keeping genes separated the species into two distinct lineages. These two lineages seem to have evolved differently. The food spoilage strain NVH1032 was distantly related to all other strains evaluated. The MLST scheme developed in the present study could be used for further studying of evolution and population genetics of B. licheniformis. Acknowledgements We thank Ingjerd Thrane for valuable technical assistance in order to complete this work. The work was supported by grants from the Norwegian Research Council (grant 178299/I10) and the Norwegian Defence Research Establishment (FFI). Electronic supplementary material Additional file 1: Cluster analysis of individual MLST candidate loci.