Banca de QUALIFICAÇÃO: LETÍCIA RODRIGUES CUEBAS HERNANDES
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : LETÍCIA RODRIGUES CUEBAS HERNANDES
DATA : 08/03/2021
HORA: 09:00
LOCAL: Link a ser definido pelo Presidente
TÍTULO:
Development and evaluation of biodegradable microcapsules containing biofungicide for agriculture.
PÁGINAS: 102
GRANDE ÁREA: Outra
ÁREA: Multidisciplinar
RESUMO:
Along with the great agriculture development, using disease control agents in plants has become essential to increase crop yield production demanded by the last century’s fast-growing human population. Among the many technologies used for pest control, microcapsules containing microbiological control agents stand out for being an alternative to chemical control, leaving no residue in the soil, and having host specificity. This work aimed to develop calcium alginate microcapsules (less than 150 μm) containing Bacillus amyloliquefaciens employing the emulsification method. It was used four process parameters [surfactant type (SpanTM 20, TweenTM 20, SpanTM 80, TweenTM 80), alginate concentration (3.5% and 5.0%), surfactant concentration (1%, 3%, and 5%) and stirring rate (500 rpm, 1000 rpm, 1500 rpm). A Full Factorial Design (FFD) was performed to determine the optimal microencapsulation conditions. For a deep understanding of emulsification and microcapsules formation steps, an I-Optimal Design (IOD) was carried out. A growth curve was obtained to verify the bacterial development phases and select the required cultivation time to reach the stationary phase. Bacteria microencapsulation happened after the selection of the optimal formulation in FFD. FFD showed that the surfactant Span20 formed the smallest microcapsules, between 47 and 94 μm in diameter, and indicated through response surfaces the lowest concentrations of alginate and the highest stirring rates led to smaller particle sizes, regardless of the type of surfactant. In IOD results, it was found that the ‘type of surfactant’ was the most statistically significant in the emulsification step, while in the formation of the microparticles, all parameters show the same significance. Fourier-transform infrared spectroscopy (FT-IR) spectra showed absorption bands at 1594 cm-1 and 1415 cm-1 for calcium alginate microcapsules, which were different from those initially presented by sodium alginate (1600 cm-1 and 1411 cm-1). This fact is attributed to sodium alginate cross-linking, and it evidences the calcium alginate formation. The same difference was also seen in the thermogravimetric analysis (TGA), which presented distinct curves between the raw material and microcapsules. The first event of moisture loss represented 13.5% and 83.0% of sodium and calcium alginate, respectively, and the second event related to polymeric chain degradation of sodium alginate was observed at 262 ºC and was not observed for calcium alginate. Bacteria growth curve showed the stationary phase was reached after 27.5 hours of cultivation. FFD results revealed the formulations (3.5% and 5.0% alginate, 1000 and 1500 rpm) had encapsulation efficiency greater than 90%, except for the 3.5% alginate sample at 1000 rpm was 51.7%.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1676364 - JULIANA MARCHI
Membro Titular - Examinador(a) Externo ao Programa - 1844792 - AMEDEA BAROZZI SEABRA
Membro Titular - Examinador(a) Externo à Instituição - EDUARDO ROBERTO DE ALMEIDA BERNARDO
Membro Suplente - Examinador(a) Interno ao Programa - 035.297.869-42 - RUBIA FIGUEREDO GOUVEIA - UNICAMP
Membro Suplente - Examinador(a) Interno ao Programa - 1763443 - MARCIA APARECIDA DA SILVA SPINACE
Membro Suplente - Examinador(a) Externo à Instituição - DANIEL BELCHIOR ROCHA