Projeto de dimensionamento de biorreator em escala piloto para produção de Bradyrhizobium sp.

Abstract

Inoculants, biotechnological products formed by a pool of beneficial bacteria, have been positively impacting productivity and sustainability in crops. Among the inoculants, those containing pregnancy-fixing bacteria stand out, being the best known and applied according to the genus Bradyrhizobium sp. These plants establish a symbiotic relationship with leguminous roots, improving water and nutrient absorption and increasing the plant's ability to withstand environmental stresses. The inoculants are produced in aerated and mechanically agitated bioreactors. Bioreactors are simultaneous systems to favor cell growth by homogenizing the culture medium with the cells, maintaining the physical and metabolic integrity of the microorganism. The great growth of the inoculant market and the complexity of its production process, bring to light the need to deepen research and development in the area, in order to generate more knowledge about the stages of preparation of a productive scale of this bioproduct. Therefore, the present objective work demonstrates the theoretical calculations of the scale-up of the production of Bradyrhizobium sp., in order to reach optimal conditions of cultivation in the pilot bioreactor. From the theoretical calculations of the scaling criteria (Reynolds Number – Nre; Power per unit volume – P/V; Velocity at the impeller end – Vtip; Volumetric oxygen transfer coefficient - KLa), it was concluded that the KLa is the most suitable for scaling up. By keeping the KLa constant (KLa = 7.07E-03) in the pilot bioreactor, the process parameters remained optimal, corroborating the fact that preserved oxygen is an essential factor for the growth of Bradyrhizobium sp. Furthermore, there will be no need to change the engine, making the cost of tank modifications lower and facilitating future practical tests.