Effects of fed-batch and continuous fermentations on human lysozyme production by Kluyveromyces lactis K7 in biofilm reactors

Lysozyme is a lytic enzyme, which has antimicrobial activity. It has been used for food and pharmaceutical applications. This study was undertaken to evaluate fed-batch and continuous fermentations for the human lysozyme production in biofilm reactor. Results showed that addition of lactose the mid-log phase to make the concentration back to the initial level generates higher lysozyme production (177 U/ml) compared with lactose addition in late-log phase (174 U/ml) (p < 0.05). Moreover, fed-batch fermentation with glucose as initial carbon source and continuous addition of lactose with 0.6 ml/min for 10 h demonstrated significantly higher lysozyme production (187 U/ml) compared to the batch fermentation (173 U/ml) (p < 0.05). In continuous fermentation, biofilm reactor provided significantly higher productivity (7.5 U/ml/h) compared to the maximum productivity in suspended cell bioreactor (4 U/ml/h), because the biofilm reactor provided higher cell density at higher dilution rate compared to suspended cell reactor (p < 0.05).