A comprehensive method for modeling and simulating ion exchange chromatography of complex mixtures

Novel processes to obtain pneumococcal surface proteins for vaccines

Current pneumococcal vaccines are based on the protection offered by capsular polysaccharides from only a few from > 100 serotypes; therefore, serotype-independent vaccines composed of pneumococcal surface proteins are being developed. Despite the immense number of publications on the discovery, characterization, and evaluation of new pneumococcal vaccine candidates, there are very few that describe the bioprocess development, which is an essential step to generate material for pre-clinical and clinical tests, to obtain enough protein amount for physical-chemical, biochemical, and biological characterization, and to understand critical product and process attributes. Here, aspects of production and purification processes of pneumococcal surface proteins are reviewed, the most common bioreactor cultivation strategies are discussed, and important features of the purification process are explored to bring new insights about the correlation between protein structure and chromatography. The process development oriented to an industrial scale is an essential step for the success of novel protein-based pneumococcal vaccines and can preclude problems that could be hardly identified at flask scale production. Moreover, the early bioprocess development should favor a smooth scale-up and transfer of the process to GMP facilities for future production of new pneumococcal vaccines. KEY POINTS: • Early bioprocess development is crucial to advancing pneumococcal protein vaccines. • Bioreactor cultivation can help to identify possible process bottlenecks. • Structural features of similar proteins can orient purification process development.

Protein adsorption to poly(ethylenimine)-modified Sepharose FF: IX. Further studies on counterion effects and behavior in therapeutic protein separation

Our previous studies on protein adsorption onto anion-exchangers of poly(ethylenimine) (PEI)-grafted Sepharose FF (PEI-Sepharose) proved their significantly improved performance over the commercial nongrafting anion-exchangers such as Q Sepharose FF, and it was found the protein adsorption behavior on PEI-Sepharose was more sensitive to counterions (Cl-, SCN-, HPO42- and SO42-). However, the complicated role of counterions has not been well interpreted due to their distinct chemical and physical characteristics. Thus, we have further studied the counterion effects by adding two halide ions (F- and Br-) to explore the effects of the three halide ions on bovine serum albumin adsorption and the results were compared with previous data. Furthermore, separation of recombinant human serum albumin (rHSA) from fermentation broth was studied. It was found that the counterion preference for PEI-Sepharose increased with the charge density of the counterions, demonstrating the favorable elution by choosing a proper counterion. Moreover, uptake kinetics onto PEI-Sepharose was very sensitive to counterions, even the three halide ions. In contrast, there is little difference among the halide ions for dynamic binding capacity of PEI-Sepharose, presenting a high value (104 ± 3 mg/mL) for the three halide ions. Furthermore, PEI-Sepharose exhibited much higher rHSA separation performance over Q Sepharose FF, characterized by sharper and more symmetrical elution peaks, higher recovery, enriched eluates, and reduced use of elution salt. The high recovery (>90 %) of rHSA from the Pichia pastoris culture supernatant proved the superiority of PEI-Sepharose column in downstream processing of therapeutic proteins.

Automatic procedure for modelling, calibration, and optimization of a three-component chromatographic separation

The current landscape of biopharmaceutical production necessitates an ever-growing set of tools to meet the demands for shorter development times and lower production costs. One path towards meeting these demands is the implementation of digital tools in the development stages. Mathematical modelling of process chromatography, one of the key unit operations in the biopharmaceutical downstream process, is one such tool. However, obtaining parameter values for such models is a time-consuming task that grows in complexity with the number of compounds in the mixture being purified. In this study, we tackle this issue by developing an automated model calibration procedure for purification of a multi-component mixture by linear gradient ion exchange chromatography. The procedure was implemented using the Orbit software (Lund University, Department of Chemical Engineering), which both generates a mathematical model structure and performs the experiments necessary to obtain data for model calibration. The procedure was extended to suggest operating points for the purification of one of the components in the mixture by means of multi-objective optimization using three different objectives. The procedure was tested on a three-component protein mixture and was able to generate a calibrated model capable of reproducing the experimental chromatograms to a satisfactory degree, using a total of six assays. An additional seventh experiment was performed to validate the model response under one of the suggested optimum conditions, respecting a 95 % purity requirement. All of the above was automated and set in motion by the push of a button. With these results, we have taken a step towards fully automating model calibration and thus accelerating digitalization in the development stages of new biopharmaceuticals.

An overview on the current status and future prospects in Aspergillus cellulase production

Cellulase is a new research point besides glucoamylase, amylase, and protease in the enzyme industry. Cellulase can decompose lignocellulosic biomass into small-molecule sugars, which facilitates microbial utilization; thus, it has a vast market potential in the field of feed, food, energy, and chemistry. The Aspergillus was the first strain used in cellulase preparation because of its safety and non-toxicity, strong growth ability, and high enzyme yield. This review provides the latest research and advances on preparing cellulase from Aspergillus. The metabolic mechanisms of cellulase secretion by Aspergillus, the selection of fermentation substrates, the comparison of the fermentation modes, and the effect of fermentation conditions have been discussed in this review. Also, the subsequent separation and purification techniques of Aspergillus cellulase, including salting out, organic solvent precipitation, ultrafiltration, and chromatography, have been declared. Further, bottlenecks in Aspergillus cellulase preparation and corresponding feasible approaches, such as genetic engineering, mixed culture, and cellulase immobilization, have also been proposed in this review. This paper provides theoretical support for the efficient production and application of Aspergillus cellulase.