Banca de DEFESA: TÚLIO ALEXANDRE FREIRE DA SILVA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : TÚLIO ALEXANDRE FREIRE DA SILVA
DATE: 17/04/2024
TIME: 14:00
LOCAL: Remoto
TITLE:
Innovations in the Production of Bacillus thuringiensis Toxins with Larvicidal and Antimicrobial Activity:
Exploring the Influence of Oxygen Carriers and Microencapsulation Strategies
KEY WORDS:
Bacillus thuringiensis, Spodoptera frugiperda, delta-endotoxin, mastitis, microcapsules
PAGES: 110
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Infecciosas de Animais
SUMMARY:
Bacillus thuringiensis (Bt) is a bacterium well known in the industry for its toxins with entomotoxic and antimicrobial activity. Its production faces challenges due to the need for high levels of oxygen, which affect the production and toxicity of the toxins. An efficient technique to increase oxygenation of the culture medium is the use of oxygen carriers. Furthermore, the short half-life of toxins when applied to organic tissues or agricultural systems is a challenge that can be overcome by encapsulating the toxins using biopolymers. Therefore, the aim of this thesis was to evaluate the effect of oxygen carriers (corn, soybean, and sunflower oil) on toxin production by Bt. Additionally, the microencapsulation of delta-endotoxins and VIP toxins was also evaluated. Through factorial design, the best combination of oxygen carriers was defined as 3% corn oil and 3% sunflower oil, resulting in a significant increase in delta-endotoxin concentration. Toxins produced under this condition demonstrated an approximately 40% and 75% increase in toxicity against the etiological agents of mastitis and Spodoptera frugiperda, respectively. Furthermore, microencapsulation of delta-endotoxins was carried out using palm forage mucilage, achieving a maximum yield of approximately 60% and an efficiency of 65%. When tested against Staphylococcus aureus isolated from goat mastitis, the capsules showed higher activity compared to free toxins. On the other hand, VIP toxins were encapsulated using the polymer policaju, with a yield of 96%. These capsules demonstrated higher activity against S. frugiperda and provided protection against UV-B rays, thereby increasing their halflife. In summary, the combination of corn and sunflower oil can act as an oxygen carrier, increasing toxin production by Bt, thus contributing to an increase in toxicity. Additionally, the microencapsulation of deltaendotoxins and VIP toxins using the methods developed in this thesis suggests that these approaches could represent significant advancements in the practical application of Bt toxins, potentially positively impacting agriculture and public health.
COMMITTEE MEMBERS:
Presidente - ANA LUCIA FIGUEIREDO PORTO
Interna - TATIANA SOUZA PORTO
Interna - MARIA TACIANA CAVALCANTI VIEIRA SOARES
Interna - RAQUEL PEDROSA BEZERRA
Externa à Instituição - MARCIA NIEVES CARNEIRO DA CUNHA
Externo à Instituição - JOSÉ DE PAULA OLIVEIRA - IPA
Externo à Instituição - JOSÉ MANOEL WANDERLEY DUARTE NETO
Externo à Instituição - LEANDRO FRAGOSO LINS