Modeling of microbial growth and ammonia consumption at different temperatures in the production of a polyhydroxyalkanoate (PHA) biopolymer

Modeling of microbial growth and ammonia consumption at different temperatures was developed in the production of a polyhydroxyalkanoate (PHA) biopolymer in Pseudomona fluorescens in the range of 25-35 °C. A logistic model was employed to predict accurately the microbial growth limiting conditions of nitrogen. A new model based in a mixed mathematical equation comprising a logistic model, and a magnetic saturation model resulted appropriate to estimate the ammonia consumption under limiting conditions. Favorable conditions for PHA production in P. fluorescens were found at temperature of 30 °C, reaching the maximum biomass concentration of 2.83 g L^-1, and consuming 99.9% of the initial ammonia, to produce 2.13 g L^-1 of PHA. The proposed models could be useful to predict the behavior of a fermentation process to produce PHA in real time.