Direct recovery of malate dehydrogenase from highly viscous yeast cell homogenate by a fluidized bed contactor equipped with an agitator

A fluidized bed adsorption system equipped with an agitator was utilized in this study to direct recover malate dehydrogenase enzyme (MDH) from highly turbid yeast cell homogenate. The adsorption and desorption characteristics of STREAMLINE Direct HST, a high-density mixed-mode adsorbent, for the recovery of MDH from the complex cell homogenate were investigated using equilibrium and kinetic studies. The adsorption of MDH was influenced by adsorption pH, ionic strength, feedstock hydrophobicity, and loading of cell homogenate. The elution of MDH from the adsorbent in packed-bed mode was also demonstrated. Subsequently, dynamic binding performance of STREAMLINE Direct HST in stirred fluidized bed adsorption (SFBA) mode was studied using different rotating speeds of agitator, process liquid velocities, and types of cell homogenate. The effect of cell homogenate viscosity on fluidization characteristics was evaluated. MDH was successfully recovered from 100 mL of crude yeast cell homogenate in a single step, recording 80.45% of MDH yield and a purification factor of 73.23. The SFBA process was scaled up using a 50-mm (internal diameter) adsorption column. The scale-up operation showed a similar performance of MDH purification, proving the linear scalability of this adsorption technique. The elution efficiency and purification factor for MDH can be improved to ∼90% and 73–79 folds by using 10 mM NADH/0.1 M NaCl as a specific eluent.