[Optimization and scale-up of recombinant elastomeric protein expression and fermentation process]

Recombinant elastomeric protein exhibits excellent biocompatibility, tunable mechanical properties, and biomimetic microenvironment characteristics, offering broad application prospects in the biomedical and food sectors. However, its low production efficiency has hindered further research and industrial translation. To address this challenge, this study established a stable and efficient large-scale preparation process through a multi-stage optimization strategy. First, codon optimization of ure(80) increased the yield to 0.42 g/L. Targeted truncation analysis identified amino acid residues 50-59 as a key region limiting expression. Subsequent secondary codon optimization and mRNA structure optimization targeting this region, combined with rational design of the ribosome-binding site (RBS), led to the construction of a high-producing engineered strain, Escherichia coli BL21(DE3)/pET-28a-80opt-R1, which achieved a yield of 0.62 g/L-a two-fold increase compared with the initial yield. Second, response surface methodology was employed to optimize the concentrations of carbon source, nitrogen source, trace elements, and vitamin B1 in a minimal salt medium, while fermentation parameters including induction temperature, induction duration, pH, and IPTG concentration were optimized, increasing the protein yield to 3.5 g/L. Upon scale-up in a fermenter, leveraging its superior mass transfer and process control capabilities, the final yield reached 5.0 g/L, representing a 16.7-fold increase over the initial yield (0.3 g/L). Cellular functional assays confirmed that cell proliferation and adhesion were not adversely affected. This study provides a reliable process for the large-scale preparation of recombinant elastomeric protein and offers a reference for the industrial production of other complex proteins.