زينب روستاازاد

In recent years, solid-state fermentation has gained attention as a suitable method for producing cellulase enzymes. Obviously, the successful application of this method requires a deeper understan‎ding of its various aspects, which can ultimately be manifested in a suitable mathematical model. In solid-state fermentation, there are limitations such as low mass an‎d heat transfer rates within the bed, which consequently lead to a gradual increase in temperature. If the temperature is not controlled, it can cause the death of microorganisms. In this research, to study the growth kinetics an‎d determine the constants of the relevant equation, experimental CO2 values from a paper that utilized small tubular bioreactors with a working volume of 20 ml an‎d aeration at a flow rate of 0.33 cm³/s were used. To determine the temperature changes an‎d energy equations governing the bioreactor, design specifications from another article were used for an aluminum packed-bed bioreactor, without a jacket, with a total volume of 127 liters, a working volume of 57 liters, an‎d equipped with an aeration system with a flow rate of 33.3 cm³/s, assuming constant porosity, heat capacity, an‎d thermal conductivity of the bed. In this research, the logistic model was proposed to describe the growth of the filamentous fungus Aspergillus niger, a cellulase enzyme producer, an‎d the relevant parameters were determined under different temperature conditions an‎d 66% humidity in the MATLAB environment. The results of predicting temperature distribution considered various heat transfer terms including conduction, convection, evaporation, an‎d heat generated due to microorganism metabolism. Among these, axial conductive heat transfer played a lesser role due to the bioreactor being equipped with an aeration system. The amount of cellulase enzyme production, assuming uniform product generation in a larger-scale packed-bed bioreactor, was solved numerically in the MATLAB software environment. Based on the model, a good agreement was observed between the experimental data (extracted from the article) an‎d the presented model.

مدل‌سازي رياضي، آنزيم سلولاز، تخمير حالت جامد، بيوراكتور بستر آكنده، آسپرژيلوس نايجر

Mathematical modeling, cellulase enzyme, solid-state fermentation, packed bed bioreactor, Aspergillus niger

Zeynab Roostaazad

Dr. Parisa Hejazi