Soluble expression of bioactive recombinant porcine-human chimeric uricase mutant employing MBP-SUMO fusion system.

Urate oxidase is a promising biological medicine for hyperuricemia treatment, but immunogenicity obstructs the development of its clinical application. The recombinant porcine-human chimeric uricase mutant named dHU-wPU is a humanized chimeric uricase based on wild porcine uricase (wPU), which can effectively reduce the limitation of potential immunogenicity with a high homology (92.76%) to deduced human uricase (dHU). Unfortunately, the insoluble expression form of dHU-wPU in E. coli increases the difficulty of production. In this study, we described a more convenient method to efficiently obtain recombinant dHU-wPU protein from E. coli. Combination small ubiquitin-related modifier protein (SUMO) and maltose-binding protein (MBP) was employed to achieve the soluble expression of dHU-wPU. MBP-SUMO-dHU-wPU fusion protein was not only overexpressed in a soluble form, but also showed high purification and cleavage efficiency. Subsequently, we optimized the culture conditions of shake flasks and expanded the production of MBP-SUMO-dHU-wPU fusion protein in a 5 L bioreactor. Finally, about 15 mg of recombinant dHU-wPU was obtained from 1 L M9 fermentation culture by using two-step affinity chromatography, with a SDS-PAGE purity over 90%. In vitro activity analysis showed that dHU-wPU had better ability to catalyze uric acid than wPU.

Towards an Efficient Generalization of the Online Dosage of Hydrogen Peroxide in Photo-Fenton Process to Treat Industrial Wastewater.

This work addresses the dosage of H2O2 in photo-Fenton processes and the monitoring of Dissolved oxygen (DO) that can be used to drive the dosage of H2O2. The objective of this work is to show that a smarter monitoring of a process variable such as DO (for which on-line measurement can be inexpensively obtained) enables the proposal and implementation of efficient dosage strategies. The work explores the application of a recent proposed strategy consisting of: (i) initial H2O2 addition, (ii) continuous H2O2 addition until a DO set up is reached, and (iii) automatic H2O2 addition by an on-off control system based on DO slope monitoring, and applies it to the treatment of different individual contaminants and their mixtures (paracetamol and sulfamethazine). The assays performed following this dosage strategy showed improved values of TOC removed per H2O2 consumed. For the case of sulfamethazine, this improvement increased up to 25-35% with respect to the efficiency obtained without dosage. Furthermore, a deeper analysis of the results allowed detecting and assessing the opportunity to redesign the dosage scheme and reduce its complexity and the number of control parameters. The promising results obtained are discussed in regard of future research into further increasing the simplicity and robustness of this generalized control strategy that improves the applicability of the photo-Fenton process by reducing its operating costs and increasing automation.

An experimental approach to the optimization of the dosage of hydrogen peroxide for Fenton and photo-Fenton processes.

The determination of the hydrogen peroxide dosage scheme that minimizes hydrogen peroxide consumption while meeting the specified treatment outcome is crucial for Fenton and photo-Fenton processes. The challenge is building a methodology that provides the optimal dosage profile. However, the lack of detailed dynamic models prevents exploiting model-based optimization methods that have proved successful in other applications. Thus, this work addresses this challenge by providing a problem formulation identifying and discussing objectives and constraints, and the nature of the optimal solution. From this point, the work presents a novel dosage model and a consequent methodology aimed at experimentally optimizing the dosage profile along a discretized time horizon following recipe optimization concepts. The approach is parallel to the numerical solution of the model-based optimization problem posed by hydrogen peroxide dosage. The proposed methodology is validated in the remediation of a Paracetamol (PCT) solution, and the obtained results are assessed and discussed in regard of the evolution of the concentration of hydrogen peroxide, the contaminant (PCT), and Total Organic Carbon (TOC). The concentration of dissolved oxygen (DO), which is also monitored, allows providing a more comprehensive explanation of the nature of the process.