Abstract

Many environmental problems have been associated with the disposal of petroleum based polymers in the nature. Based on this, alternatives to these polymers have been studied, like the production of biodegradable polymers. The poly(3-hydroxybutyrate) (P(3HB)) is a biodegradable biopolymer that can be produced by many microorganisms, in unbalanced media conditions such as nitrogen or oxygen limitation, as storage of carbon and energy. Despite of its properties, that are similar to those of the petroleum based polymers, the production costs are high which harms its application. One of the most studied microorganisms, for this production, is the bacterium Cupriavidus necator that has the ability of producing more than 80 % of its dried mass in polymer and assimilate different kinds of carbon sources. The development of models that can describe the behavior of the microorganism during P(3HB) production, may facilitate the study and the understanding of the production process, leading to scenarios that can improve the productivity and reduce biopolymer production cost. The main goal of this work was to validate a structured model, based in the metabolic flux analysis presented in the literature, developed to the P(3HB) production by C. necator, through the assimilation of glucose. One batch culture was conducted with initial glucose concentration of 48 g/L and initial nitrogen concentration of 1.2 g/L which led to a nitrogen limitation, and consequently production of P(3HB), after 15 hours. The concentration of the other nutrients was high enough to avoid its limitation. The same initial conditions were used to simulate the behavior of the culture applying the developed structured model. The result of the simulation showed that the model represented pretty well the experimental data, with coefficients of determination (R²) of 0.999, 0.998 and 0.996 to the total biomass’s, the residual biomass and the P(3HB) production, respectively. The percentage of P(3HB) in the end of the culture was 61 and 62.5 % for the experimental results and for the simulation, respectively. It is possible to conclude that the structured model could represent the experimental behavior of the P(3HB) production by C. necator, and can be applied to predict the response of different culture conditions.