Develop Mechanistic Models of Transition Periods between Lag/Exponential and Exponential/Stationary Phase

A continuing goal in predictive microbiology is models directly based on physiological behavior. Buchanan et al.¹ hypothesized that (1) the curvilinear lag/exponential transition represents the variability of cells in the adjustment (t_a) and metabolic (t_m) periods, and (2) the exponential/stationary transition is determined by limiting nutrient diffusion rates. Nutritional shift trials were conducted to estimate E.coli K-12 growth. Lactase production time suggest that lactase gene translation occurs after completion of lag phase. Agitation rates and inoculum sizes both influenced the shape of the exponential/stationary phase transition. Monte Carlo simulations allowed the generation of sigmoidal growth curves while considering physiological events.