Optimization of recombinant human lysozyme using Kluyveromyces lactis K7

Optimization of recombinant human lysozyme production using Kluyveromyces lactis K7 was attempted in this study. Lysozyme has been known to be a natural antimicrobial agent, and it has already been used in the food industry in cheese making and in some alcoholic beverages. Currently its therapeutic uses are still being evaluated by other scientists. The main commercial source of lysozyme currently comes from hen egg white. However, human lysozyme has approximately 2.5 times higher antimicrobial activity than hen egg white lysozyme. Kluyveromyces lactis is proposed as a non-conventional yeast which has several advantages over other yeast such as Saccharomyces cerevisiae. In our study, the production of recombinant human lysozyme was optimized using a 1.25-Liter bioreactor. It was determined that 25°C was the optimal temperature for human lysozyme production. We observed that fermentation with no pH control during fermentation demonstrated higher yield than with pH controlled near neutrality. Oxygen limitation also resulted in higher yields for recombinant human lysozyme production. Overall, this study demonstrated that the yield of human lysozyme increased from 64.1 units/ml in flask study to 123.6 units/ml in fed-batch fermentation using 4.5% (w/v) glucose as initial carbon source and 9% lactose as feed.