Bacilli

There are two main bacterial kingdoms, eubacteria (or Bacteria) and archaebacteria (Archaea). Bacteria are split into two broad domains, distinguished by the way in which they may be colored by a pigment (the "Gram" test). Bacillus subtilis is the universally recognized model for eubacteria of the sporulating A+T-rich Gram positive category. Gram-positives have a single envelope, comprising a lipid bilayer (cytoplasmic membrane) and a more or less complex set of protective layers. Bacillus subtilis is both a model for bacteria used in agro-food industry, and for dangerous pathogens.