Hydrocarbon fermentation: Kinetics of microbial cell growth

Modeling of microbial growth using nonmiscible substrate is studied when kinetics of substrate dissolution is rate limiting. When the substrate concentration is low, the growth rate is described by an analytical relation that can be identified as a Contois relationship. If the substrate concentration is greater than a critical value S_crit, the potentially useful hydrocarbon S* concentration is described by S* = S_crit/(1 + S_crit/S). A relationship was found between S_crit and the biomass concentration X. When X increased, S_crit decreased. The cell growth rate is related to a relation μ = μ_mA(X/S_crit)(1 + S_crit/S) + 1]^?1. This model describes the evolution of the growth rate when exponential or linear growth occurs, which is related to physico-chemical properties and hydrodynamic fermentation conditions. Experimental data to support the model are presented.