DEVELOPMENT OF FED-BATCH IN YEAST PRODUCTION

This study aimed to optimize brewer's yeast replication, aiming to increase cell biomass and culture efficiency, focusing on the development and adjustment of a fed-batch system and its instrumentation. An adapted bioreactor (Nalgene Clearboy) with aeration controlled by PFTE membrane and sintered stone, and magnetic agitation was used. For the fed-batch regime, a peristaltic pump (3D printed housing designed using Fusion360®/Cura®) was designed and manufactured powered by a NEMA 17 stepper motor, driven with a model A4988 driver and controlled by an Arduino-Nano programmed through the IDE-ARDUINO.® The control software dynamically adjusted the feed flow rate, estimating the demand for sugars to compensate for the absence of glucose sensors in real time, the feed estimate was calculated through the mass balance in the conversion of sugars into cell mass; pH (pH meter MS Tecnopon) and density (ATC refractometer) were monitored offline. The results showed a significant increase in cell density, reaching 5.1×10⁸ cells/mL in the fed-batch system, five times higher than previously obtained in batch. The correction of the C:N ratio and the use of yeast extract were crucial, which helped to maintain the pH around 5. The customized peristaltic pump allowed for the implementation of the fed-batch, although the feed rate was adjusted empirically due to the absence of real-time sensors for glucose, dissolved oxygen, and pH, and limitations in medium agitation were also observed, restricting the efficiency of the magnetic bar