Otimização e escalonamento da produção do agente de controle biológico Beauveria bassiana em cultivo submerso

Abstract

The entomopathogenic fungus Beauveria bassiana is one of the main microorganisms used in the composition of biological products. Although commercial production of this bioagent is traditionally based on solid state cultivation, submerged cultivation has received increasing attention in the industry due to its numerous advantages compared to the solid cultivation process. In this context, the objective of this work was, in partnership with the company Dillon Biotechnology, to optimize the production of submerged spores (SS) of B. bassiana and scale up the submerged cultivation of the fungus in a pilot-scale bioreactor, with a focus on studying the IBCB 868, IBCB 66 and CBMAI 1306 strains. The submerged spores produced were formulated and subjected to stability and efficacy evaluations in controlling the two-spotted mite (Tetranychus urticae). The optimization of the culture medium, carried out using the Plackett-Burman (PB) experimental design followed by the central composite rotational design (CCRD), led to the achievement of SS concentrations exceeding 1×109 SS mL-1 in just three days of growth for the IBCB 868 strain of B. bassiana. Additionally, cultivations in a laboratory-scale bioreactor, conducted with the same strain, made it possible to identify the ideal pH and dissolved oxygen conditions for optimal growth of the fungus. Solid formulations were developed for the strains based on growth in the optimized culture medium. The formulated products proved effective in controlling the spider mite and remained stable after 90 days of storage under refrigeration (4 ± 1 ºC) with a UFC g-1 concentration exceeding 1×109. Finally, the scaling up of the cultivation conducted with the IBCB 868 strain in a 500-liter pilot-scale bioreactor, with a 350-liter operational volume, demonstrated the possibility of obtaining substantial quantities of B. bassiana SS, above 1×109 SS mL-1 , in a short period of just three days. The results obtained in this study represent an important contribution to expanding knowledge about liquid culture, a promising technology for the development of products based on entomopathogenic fungi. [resumo fornecido pelo autor]