Albumins derived from animal or human plasma present ethical and reproducibility challenges (e.g., contamination risks, batch-to-batch variability, and animal welfare). Additionally, the growing demand for serum albumin in the cultivated meat industry far exceeds the current production capacity of recombinant proteins. While yeast-based production has been explored, it remains complex. In contrast, bacterial production offers advantages in terms of speed, cost, and efficiency, but the complex structure of albumin has precluded its heterologous production, until now.

Using the PROSS computational platform, stable designs of human and bovine serum albumins (HSA and BSA) were developed, exhibiting superior thermal stability compared to plasma-derived counterparts, of up to 40°C and even beyond the boiling point. The optimized designs were robustly expressed in E. coli in 100s of mg/l culture in standard lab settings. By contrast, the natural albumins did not express solubly. The engineered HSA and BSA variants were not toxic to HEK293T and hybridoma cells, carried typical small-molecule ligands of albumins and exhibited potent activity in restriction enzyme reactions, thus enabling applications in cell culture, and molecular biology (Figure 1).

Figure 1. Stabilized HSA and BSA designs with improved thermal properties, generated through computational modeling for cell culture, and biotech applications.

All tested stabilized variants were highly expressed in E. coli and their functional properties were validated in cell culture and in vitro applications.