Expression level of Bacillus subtilis germinant receptors determines the average rate but not the heterogeneity of spore germination

J Bacteriol. 2013 Apr;195(8):1735-40. doi: 10.1128/JB.02212-12. Epub 2013 Feb 8.


Germination of Bacillus subtilis spores can be triggered by the binding of specific nutrients, called germinants, to germinant receptors (GRs) in the spore's inner membrane. This interaction eventually initiates, with variable time delays, the release of dipicolinic acid and cations from the spore core--a key step in spore germination. The kinetics of this process are highly heterogeneous for individual spores. In this work, we sought to investigate how the germination heterogeneity was controlled. In particular, we tested whether the rates of germination were determined by GR levels, which vary from spore to spore due to stochastic gene expression. Both the expression levels of GRs and the germination rate were measured in single spores, and the experimental results were compared to theoretical predictions. Our results indicated that the variation in the expression levels of GRs was not the primary factor that controls spore germination heterogeneity. Two alternative hypotheses are discussed in light of this experimental discovery.

MeSH terms

  • Bacillus subtilis / genetics
  • Bacillus subtilis / metabolism*
  • Bacillus subtilis / physiology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Cell Membrane
  • Gene Expression Regulation, Bacterial / physiology*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Models, Biological
  • Picolinic Acids
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Spores, Bacterial
  • Stochastic Processes
  • Time Factors


  • Bacterial Proteins
  • Membrane Proteins
  • Picolinic Acids
  • Receptors, Cell Surface
  • dipicolinic acid