Three-stage fermentation and kinetic modeling of bioflocculant by Corynebacterium glutamicum

Fermentation of bioflocculant with Corynebacterium glutamicum was studied by way of kinetic modeling. Lorentzian modified Logistic model, time-corrected Luedeking–Piret and Luedeking–Piret type models were proposed and applied to describe the cell growth, bioflocculant synthesis and consumption of substrates, with the correlation of initial biomass concentration and initial glucose concentration, respectively. The results showed that these models could well characterize the batch culture process of C. glutamicum at various initial glucose concentrations from 10.0 to 17.5 g·L− 1. The initial biomass concentration could shorten the lag time of cell growth, while the maximum biomass concentration was achieved only at the optimal initial glucose concentration of 16.22 g·L− 1. A novel three-stage fed-batch strategy for bioflocculant production was developed based on the model prediction, in which the lag phase, quick biomass growth and bioflocculant production stages were sequentially proceeded with the adjustment of glucose concentration and dissolved oxygen. Biomass of 2.23 g·L− 1 was obtained and bioflocculant concentration was enhanced to 176.32 mg·L− 1, 18.62% and 403.63% higher than those in the batch process, respectively, indicating an efficient fed-batch culture strategy for bioflocculant production.

Graphical abstractA three-stage fed-batch strategy was proposed for bioflocculant production by C. glutamicum. In the three stages, i.e. the lag phase, the quick biomass growth and the bioflocculant production stages, the glucose concentration and dissolved oxygen were adjusted according to the prediction results from the modified kinetic models presented in this study. Results show that the biomass and bioflocculant production are largely improved in this three-stage fermentation over the conventional fed-batch fermentation.Figure optionsDownload full-size imageDownload as PowerPoint slide