DescriptionIn the context of protein production via fermentation processes, proteases produced by Bacillus species are a billion dollar business and set nearly 60 % of the global enzyme market. Manufacturers continuously search for new and improved proteases to meet stability and performance demands and robust production processes are important for economically viable production. Thereby, developing robust and generic on-line monitoring techniques is important to meet the need for monitoring and controlling the process at optimal conditions. Phosphorus and ammonium are central nutrients in media for Bacillus fermentations and need to be present in relevant levels to promote growth and enzyme production. Besides, both species impose additional costs on downstream wastewater treatment if more is added to the medium during the fermentation than needed by the microorganism. Hence, there are also major challenges associated with phosphate and ammonium. Note that, fermentation processes usually operate under mild conditions and the products are rather diluted. Therefore, a large amount of wastewater containing nutrients is generated that needs to be treated. On-line monitoring of phosphate and ammonium during fermentation processes would facilitate development of feeding strategies of phosphate and ammonium during protein production ensuring that the nutrients are kept at the correct level. On-line monitoring tools would also provide a better understanding of bioprocess dynamics over the entire line from upstream to downstream.
In this work, a case study focusing on the determination of concentration of phosphate and ammonium in a Bacillus protein production process is considered. Both IR and NIR in combination with partial least square regression (PLS) are being employed in this work. This combined approach provides the means for measuring phosphate and ammonium concentrations in a semi-defined culture medium through real-time/on-line monitoring. The present approach is applied on a lab-scale fermentation setup adjusting the operating conditions to mimic the real operation for an industrial application. To minimize the complexity associated with spectroscopy measurements on fermentation broth and decouple natural correlations of parameters, synthetic samples spiked with phosphate or ammonium in addition to real fermentation samples where applied in the model development process. Thereby, regions of IR and NIR spectra corresponding to phosphate and ammonium were appropriately identified and selected. One major advantage associated with this approach is its selectivity due to the appropriateness of the selection criteria (different wavelengths as variables) that are uniquely tied to the target species. Another advantage lies within the versatility of the (N)IR probe itself that can be used in various bioprocess settings. This generic method development strategy will be presented. Furthermore, the application of the on-line monitoring strategies for phosphate and ammonium during a fed-batch, protein production process will be discussed.
|Period||5 Oct 2017|
|Event title||ECAB 4|