Insights into the genetic organization of the Bacillus mycoides cryptic plasmids pDx14.2 and pSin9.7 deduced from their complete nucleotide sequence.

Bacillus mycoides, a member of the Bacillus cereus group of bacteria, can be easily distinguished from close species because of colony shape, made by filaments of cells, resembling fungal hyphae, curving clock- or counterclockwise depending on the strain. Two plasmids, one from a strain curving to the right (pDx14.2), the other from a strain curving to the left (pSin9.

Colony shape as a genetic trait in the pattern-forming Bacillus mycoides.

Background: Bacillus mycoides Flügge, a Gram-positive, non-motile soil bacterium assigned to Bacillus cereus group, grows on agar as chains of cells linked end to end, forming radial filaments curving clock- or counter-clockwise (SIN or DX morphotypes). The molecular mechanism causing asymmetric curving is not known: our working hypothesis considers regulation of filamentous growth as the prerequisite for these morphotypes.

Results: SIN and DX strains isolated from the environment were classified as B.