DYNAMIC MODELLING OF FED-BATCH PRODUCTION OF GLYCEROL-BASED POLY(3- HYDROXYBUTYRATE) (PHB)

• Main Author: Amala, Zulfah
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/65544
• Institution: Institut Teknologi Bandung

Poly(3-hydroxybutyrate) (PHB) is an intracellular carbon storage molecule synthesized by bacteria in growth-limiting conditions. PHB fermentation is often conducted in fed-batch mode with the purpose of increasing the efficiency of substrate utilization and preventing substrate inhibition. Formulation of a proper feeding strategy is the key to ensuring the success of fed-batch fermentation. This study aims to develop a feeding strategy that can maximize the final PHB concentration in a fed-batch fermentation system with Cupriavidus necator as the PHB producer and glycerol as the sole carbon source. Substrate feeding strategy is determined based on concentration profiles obtained during batch simulation with fermentation time set to 60 hours. The highest concentration of PHB is achieved by simultaneously feeding glycerol and nitrogen from the start of the simulation, terminating the nitrogen feed after 30 hours, and terminating the glycerol feed after 47 hours. The most suitable strategy is feeding the substrate in pulses every hour, resulting in a final PHB concentration of 12.53 g/L. This result is 26.18% higher than the PHB concentration obtained in batch simulation (9.93 g/L). Continuous feeding with linear flow rate of glycerol and nitrogen feed in the first stage (F = 0.0065t + 0.034 L/h) and a constant flow rate of glycerol-only feed in the second stage (F = 0.15 L/h) only gives a final PHB concentration of 11.79 g/L after optimization of parameters. The result of this study denotes that a twostage feeding strategy of carbon and nitrogen sources is suitable for application in a real fermentation setting. This simple optimization method may pose as an alternative way of developing a fed-batch feeding strategy for production of PHB as well as other molecules.