Banca de DEFESA: RAFAELA NASCIMENTO FARIA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : RAFAELA NASCIMENTO FARIA
DATE: 18/02/2022
TIME: 13:30
LOCAL: defesa de forma remota. Link: meet.google.com/nag-bibe-btb
TITLE:

Immobilization of β-glucosidase from the fungus Trichoderma yunnanense on magnetic nanoparticles

KEY WORDS:

biocatalysis, beta-glucosidase, immobilization, biomaterial, magnetic nanoparticles.

PAGES: 52
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Química dos Produtos Naturais
SUMMARY:

The main objective of this work was to synthesize a biocatalytic material starting from magnetic nanoparticles and β-glucosidase enzyme for application in the conversion of isoflavones into soybean derivatives. The β-glucosidase enzyme was produced by the fungus Trichoderma yunnanense and partially purified using ion exchange chromatography. The immobilization of β-glucosidase was performed on magnetic nanoparticles modified with silanol and amino groups, where the immobilization maintained 58% of the relative activity of the purified enzyme. After the first cycle of use, the immobilized enzyme maintained 42% of the activity and around 20% of the activity for 3 subsequent cycles. After immobilization, biochemical characterization and material characterization were performed. The optimum temperature was 60 °C for both forms of the enzyme, free and immobilized. The optimal pH was also determined, being 6.5 and 5.5 for the free and immobilized enzymes, respectively. The free and immobilized enzymes showed sensitivity to most ions, losing activity. Exceptions were potassium chloride ions and copper sulfate which activated both enzymes. The immobilized enzyme showed better performance for thermostability at 50 °C, maintaining activity up to 280 minutes of pre-incubation, while the free enzyme remained active for 180 minutes. At 70 °C, the immobilized enzyme showed activity for up to 60 minutes of pre-incubation, while the free enzyme lost its activity completely. The characterization of the material was performed by scanning electron microscopy (SEM), infrared absorption spectroscopy and thermogravimetry. The micrographs revealed a smooth and homogeneous surface for the unmodified magnetic nanoparticles, and the material showed heterogeneity as groups were added. Magnetite, which was the material used as a magnetic nanoparticle for this work, showed a low rate of thermal degradation up to 800 °C. As the organic groups were added, the mass percentage of thermal degradation of the material increased. Little difference in the amount of thermal degradation was observed between the steps of addition of the amino group and immobilization of the enzyme.

BANKING MEMBERS:
Presidente - 2254152 - MAIRA NICOLAU DE ALMEIDA
Interno - 1222623 - MARCELO SIQUEIRA VALLE
Interno - 1727278 - LUIZ GUSTAVO DE LIMA GUIMARAES
Externa à Instituição - GABRIELA PICCOLO MAITAN-ALFENAS - UFV