Enhancing Cell-Free Protein Synthesis Efficiency with Lactose-Eating Yeast

Lactose-Eating Yeast Boosts Yields and Cuts Costs for Cell-Free Protein Synthesis

The yeast Kluyveromyces lactis (K. lactis) shows promising potential as an efficient and cost-effective energy source for cell-free protein synthesis (CFPS) in biopharmaceutical manufacturing, aligning with the industry’s move towards a circular economy. It offers a notable three-to-fourfold increase in protein yields compared to Pichia pastoris (P. pastoris) CFPS systems. K. lactis stands out due to its ability to utilize lactose as its primary food source and metabolize it under aerobic conditions, contributing to improved sustainability.

Research led by Dr. Karen M. Polizzi of Imperial College London focused on developing a CFPS system utilizing K. lactis to produce proteins like erythropoietin (EPO) and green fluorescent protein (deGFP). Notably, the lactose-metabolizing capability is specific to the domestic variant of K. lactis, K. lactis var. lactis, while the wild variant, K. lactis var. drosophilarum, lacks this ability. The team evaluated 128 CFPS mixes for EPO and deGFP synthesis, determining optimal conditions at 30°C, with notable variations in activity at different temperatures.

Studies revealed that factors such as resuspension-to-pellet ratios and homogenization times significantly impact protein concentrations and overall CFPS yields. The team’s findings indicated that protein concentration serves as a reliable indicator of extract quality. Furthermore, the team observed that extending homogenization time beyond certain thresholds could influence endpoint signal strength for protein synthesis, with varying optimal times for different resuspension ratios.

Although K. lactis exhibits slower growth in lactose-based media compared to glucose-based media, the researchers highlighted the compensatory advantages of robust extracts that sustain high levels of protein synthesis in CFPS. The use of inexpensive feedstocks like whey can further offset any growth delays. The team’s identified reaction conditions consistently outperformed the initial P. pastoris-optimized mixes in terms of deGFP and EPO production, suggesting the superiority of K. lactis in this context.

The team concluded that incorporating lactose not only as a carbon source for cell growth and extract preparation but also as an energy source in the reaction mix significantly enhances CFPS productivity. This approach, using the generally-regarded-as-safe (GRAS) yeast K. lactis, presents a cost-effective strategy for producing enzymes, antibodies, and other proteins. Moreover, the potential cryoprotective role of lactose further underscores the multifaceted benefits of leveraging this yeast in CFPS applications.

Key Takeaways:
– Kluyveromyces lactis demonstrates superior protein yields and cost-effectiveness in cell-free protein synthesis (CFPS) compared to Pichia pastoris.
– Optimal synthesis conditions for proteins like erythropoietin and green fluorescent protein involve factors such as temperature, homogenization time, and resuspension ratios.
– Lactose, as a versatile carbon and energy source, enhances CFPS productivity and potentially serves as a cryoprotectant, expanding the utility of K. lactis in biopharmaceutical manufacturing.
– Leveraging lactose-eating yeast in CFPS can lead to increased efficiency, reduced costs, and improved sustainability in protein synthesis processes.

Tags: yeast, biotech