Kinetic modeling and sensitivity analysis of inulinase production in large-scale stirred tank bioreactor with sugar beet molasses-based medium

Abstract

This study aimed to produce Aspergillus niger inulinase from sugar beet molasses in large-scale bioreactor (30-L), kinetically model the fermentation in product formation and substrate consumption, and perform sensitivity analysis of kinetic models. According to the results, the resulting activities of inulinase, invertase-type, specific inulinase, and specific invertase-type were 791.35 U/mL, 616.90 U/mL, 3097.68 U/mg, and 2413.39 U/mg, respectively. Besides, kinetic parameters like maximum substrate consumption, inulinase production, invertase-type production rates, and sugar utilization yield were 0.338 g/L/h, 6.28 U/mL/h, 7.92 U/mL/h, and 85.60%, respectively. Regarding kinetic modeling, predicted values were in good agreement with data of observed substrate consumption and inulinase, invertase-type, specific inulinase, and specific invertase-type productions with high R 2 values > 0.90 (0.9778, 0.9875, 0.9415, 0.9837, and 0.9367, respectively). Sensitivity analysis of the kinetic models suggested for the production was made by different scenarios. For inulinase and specific inulinase production, the first scenario (5% increase in each model parameter) gave higher R 2 values than those of the suggested models. Besides, the second scenario (5% decrease in each model parameter) yielded also greater R 2 values than those of kinetic models for invertase-type and specific invertase-type productions. With this work, promising enzyme activities and kinetic values were achieved from sugar beet molasses in large-scale bioreactor for industrial production; however, the study should be supported with further optimization studies.