A structured model for vegetative growth and sporulation in Bacillus thuringiensis.

A mathematical model has been developed for the delta-endotoxin producing Bacillus thuringiensis. The structure of the model involves the processes taking place during vegetative growth, those leading to the initiation of sporulation under conditions of carbon and/or nitrogen limitation, and the sporulation events. The key features in the model are the pools of compounds, such as PRPP, IMP, ADP/ATP, GDP/GTP, pyrimidine nucleotides, NAD/NADH2, amino acids, nucleic acids, cell wall, and vegetative and sporulation proteins. These, along with sigma-factors that control the nature of RNA-polymerase during the different phases, effectively stimulate the vegetative growth and sporulation. The initiation of sporulation is controlled by the intracellular concentration of GTP. Results of simulation of vegetative growth, initiation of sporulation, spore protein formation, and production of delta-endotoxin under C- or N-limitation are presented.