Desenvolvimento e comparação de formulações de Bacillus thuringiensis visando à indução de esporos e cristais e ao escalonamento em biorreator

Abstract

The growing demand for sustainably produced food has driven the development of microbial bioinputs for agricultural applications. In this context, Bacillus thuringiensis stands out as one of the main microorganisms used in the production of bioinsecticides due to its ability to form spores and protein crystals with insecticidal activity. This study aimed to compare three culture medium formulations for the cultivation of Bacillus thuringiensis in order to identify the most efficient condition for cell growth, sporulation, and spore-crystal complex formation, as well as to evaluate its performance at an industrial scale. Initially, experiments were carried out in Erlenmeyer flasks, in which optical density, pH, viable cell concentration, and microscopic characteristics were monitored throughout the cultivation process. The results showed that all three formulations promoted microbial growth, reaching cell concentrations on the order of 10⁸ CFU/mL. However, differences in the physiological behavior of the cultures were observed. Formulation 1 showed delayed sporulation, whereas formulation 3 promoted early sporulation, reducing the period of cell multiplication. Formulation 2 presented the most balanced performance, achieving the highest viable cell concentration and allowing greater vegetative growth before the formation of spores and crystals. Based on these results, formulation 2 was selected for scale-up in an industrial bioreactor, maintaining high cell viability, intense spore-crystal complex formation, and absence of microbiological contamination throughout the process. It was concluded that formulation 2 showed the best performance among the evaluated conditions, demonstrating potential for application in industrial processes for the production of Bacillus thuringiensis-based bioinsecticides.