2015AbstractModeling 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 growthlimiting conditions of nitrogen. A new model based in a mixed mathematical equation comprising a logistic model, and a magnetic saturation modelresulted appropriate to estimate the ammonia consumption under limiting conditions. Favorable conditions for PHA production in P. fluorescenswere 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, toproduce 2.13 g L−1of PHA. The proposed models could be useful to predict the behavior of a fermentation process to produce PHA in real time.All Rights Reserved © 2015 Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico. This is anopen access item distributed under the Creative Commons CC License BY-NC-ND 4.0.