The upcoming climate change as well as the resulting environmental problems pose serious challenges for mankind. This can be addressed in the field of biotechnology, for example, through the utilization of renewable precursors and waste materials. The majority of bioprocesses utilize first generation food crops as feedstock, limiting the availability of food for a steadily growing world population. Second generation raw materials, especially lignocellulosic biomass, could overcome these problems, by introducing circular economy and sustainability.The European Union (EU) project iFermenter, to which this thesis contributes, is dealing with the biotechnological utilization of a waste product of the paper industry. The lignocellulosic byproduct spent sulfite liquor (SSL) is available in large quantities all over the world. However, a broad sugar pallet and inhibitors in the medium complicate application in industrial scale and limit the choice of microorganisms. One microorganism, that is capable of facing these challenges, is Corynebacterium glutamicum. However, in previous studies, only 5 – 10 % SSL in combination with a complex media was used for fermentation, which decreased the profitability and its contribution to sustainability. In this thesis, a recombinant C. glutamicum strain is used to utilize SSL as the sole carbon source for the production of pediocin PA-1, a high-value peptide with a specific activity against Listeria monocytogenes. Thereby, the optimal production conditions have to be identified, which is achieved in this work by investigating the limitation or excess of media components and by modeling of the biological behavior of the cells. For this purpose, the influence of SSL, nitrogen and phosphate availability on growth and pediocin titer in the induction phase was investigated via a Design of Experiment (DoE) approach. In order check if the obtained data can be further used in a model, the reliability was verified by assessing the elemental and electron balances. Finally, following these results, a mechanistic model was developed to identify the underlying mechanisms of the bacterium.In this study, it was shown that the phosphate concentration has a significant influence on the pediocin titer in the reaction broth. With lower phosphate availability, higher pediocin titer were observed. In contrast, no significant influence of the DoE factors on growth was detected. One reason for this could be the fact that growth was considerably reduced in the induction phase. The carbon and DoR balance meet the set acceptance criterion of ± 10 % recovery which demonstrates the fundamentals of both balances for SSL. However, the nitrogen and phosphorus balance did not meet this criterion and therefore, the corresponding data is not reliable and could not be further used. A model was established which is capable of accurately describing the uptake of the sugars mannose and xylose in batch but failed to predict the states biomass, glucose and acetate due to the high variability of the initial biomass. Moreover, the model accurately described the growth and uptake of mannose, xylose and acetate in fed-batch. However, the goal of identifying the underlying mechanisms of the product formation could not be reached due to the lack of a more precise analytical method.In summary, it was shown that the phosphate concentration is an important factor for pediocin production by C. glutamicum on SSL. Furthermore, a mechanistic model was established that can accurately describe key parameters in the induced fed-batch. However, in order to improve the modeling of pediocin formation, a more precise method of determination needs to be developed in the future.
