Immobilization of Horseradish Peroxidase on Ca Alginate-Starch Hybrid Support: Biocatalytic Properties and Application in Biodegradation of Phenol Red Dye.

In this study, horseradish peroxidase was extracted, purified, and immobilized on a calcium alginate-starch hybrid support by covalent bonding and entrapment. The immobilized HRP was used for the biodegradation of phenol red dye. A 3.74-fold purification was observed after precipitation with ammonium sulfate and dialysis. An immobilization yield of 88.33%, efficiency of 56.89%, and activity recovery of 50.26% were found. The optimum pH and temperature values for immobilized and free HRP were 5.0 and 50 °C and 6.5 and 60 °C, respectively. The immobilized HRP showed better thermal stability than its free form, resulting in a considerable increase in half-life time (t1/2) and deactivation energy (Ed). The immobilized HRP maintained 93.71% of its initial activity after 45 days of storage at 4 °C. Regarding the biodegradation of phenol red, immobilized HRP resulted in 63.57% degradation after 90 min. After 10 cycles of reuse, the immobilized HRP was able to maintain 43.06% of its initial biodegradative capacity and 42.36% of its enzymatic activity. At the end of 15 application cycles, a biodegradation rate of 8.34% was observed. In conclusion, the results demonstrate that the immobilized HRP is a promising option for use as an industrial biocatalyst in various biotechnological applications.

Immobilization of commercial horseradish peroxidase in calcium alginate-starch hybrid support and its application in the biodegradation of phenol red dye.

In this study, horseradish peroxidase (HRP) was immobilized for the first time on Ca alginate-starch hybrid beads and employed for the biodegradation of phenol red dye. The optimal protein loading was 50 mg/g of support. Immobilized HRP demonstrated improved thermal stability and maximum catalytic activity at 50 °C and pH 6.0, with an increase in half-life (t1/2) and enzymatic deactivation energy (Ed) compared to free HRP. After 30 days of storage at 4 °C, immobilized HRP retained 109% of its initial activity. Compared to free HRP, the immobilized enzyme exhibited higher potential for phenol red dye degradation, as evidenced by the removal of 55.87% of initial phenol red after 90 min, which was 11.5 times greater than free HRP. In sequential batch reactions, the immobilized HRP demonstrated good potential efficiency for the biodegradation of phenol red dye. The immobilized HRP was used for a total of 15 cycles, degrading 18.99% after 10 cycles and 11.69% after 15 cycles, with a residual enzymatic activity of 19.40% and 12.34%, respectively. Overall, the results suggest that HRP immobilized on Ca alginate-starch hybrid supports shows promise as a biocatalyst for industrial and biotechnological applications, particularly for the biodegradation of recalcitrant compounds such as phenol red dye.

Nutritional, textural and sensory properties of lasagna dough containing air yam, a non-conventional edible plant.

The incorporation of non-conventional edible plants into gluten-free food products shows potential and the ability to increase nutritional properties. Therefore, the aim of this study was to develop a gluten-free air yam-based lasagna dough and to evaluate the nutritional, textural, and sensory properties. First, the air yam flour was obtained by drying the tubers at 55 °C for 16 h and then, mixed with the water and egg powder, it constituted the lasagna dough. The nutritional composition and bioaccessible mineral content of air yam flour and lasagna dough were evaluated, as well as the texture, microbiological and sensory properties of the lasagna dough. The results indicated that air yam flour and the lasagna dough had high dietary fiber contents, 17.1% and 9.4%, respectively. Additionally, the low-fat content found means that the lasagna dough can be considered both gluten-free and fat-free. The most bioaccessible mineral present was K in both air yam flour and lasagna dough. In sensory analysis, the lasagna dough containing air yam showed an intermediate acceptability in relation to two already commercialized lasagna doughs. This study shows an application to this group of plants that are still little explored, allowing the development to consumers and industries.

Degradation of micropollutant cephalexin by ultraviolet (UV) and assessment of residual antimicrobial activity of transformation products.

Cephalexin (CEX) is an antibiotic commonly used to treat bacterial infections in humans and animals. However, it is also a micropollutant. Thus, this study evaluated the degradation of CEX using ultraviolet irradiation (UV-C) and analyzed the by-products as well as their residual antimicrobial activity. A reactor with a mercury vapor lamp was used for the degradation. Irradiated CEX solutions were collected over a period of 4 hours and analyzed using high-performance liquid chromatography coupled with mass spectrometry. For the residual antimicrobial activity the susceptibility test was performed using Staphylococcus aureus and Escherichia coli microorganisms by broth microdilution. It was found that CEX, after treatment, generated a metabolite with a mass of 150 m/z in 15 min. A four- and eightfold increase in the minimum inhibitory concentration of the drug against S. aureus and E. coli could be observed, respectively, after 20 min. Therefore, this treatment proved to be effective in the degradation of CEX, being able to degrade 81% of the initial molecule of the drug in 20 min. Furthermore, the antimicrobial activity of the CEX solution decreased as the irradiation time increased, indicating loss of antimicrobial function of the initial CEX molecule and the resulting by-products.