Sporulation occurs in this phase of bacterial growth curve:

Ref: Microbiology by Ananthanarayan and Paniker, 8th ed. P 24PHASES OF BACTERIAL GROWTH CURVELAG PHASE* No appreciable increase in number but there is increase in size of the cells* Accumulation of enzymes and metabolic intermediates* Maximum cell size is obtained at the end of lag phaseLOG PHASE* Also called exponential phase* Number of cells increase exponentially* Cells are small and stain uniformly* Increase in metabolic rateSTATIONARY PHASE* Viable count of cells remain stationary as an equilibrium exists between dying cells and newly formed cells* Cells are viable and show irregular staining due to intracellular storage granules* Sporulation occurs at this stage* Production of antibiotics and exotoxinsPHASE OF DECLINE* Population of cells decrease due to cell death* Involution forms are common