Biolistic Transformation and Expression of Functional Chymosin from a Codon-Optimized Synthetic Bovine Gene in Tobacco Plants

Chymosin is an important milk clotting enzyme, massively used in the dairy industry. Due to the limited amount of natural chymosin, the recombinant enzyme produced in different organisms is the main source of chymosin. Plants have several advantages for large scale cost-effective production of recombinant chymosin. Here, we used a synthetic codon-optimized version of bovine prochymosin gene for ideal expression in the tobacco host. In this study, we utilized biolistic co-transformation method to introduce the synthetic bovine prochymosin gene into the tobacco genome. Several transgenic plants were regenerated on a selective medium. Molecular analysis confirmed successful integration and expression of prochymosin gene in several transgenic candidates. Total soluble protein extracts from transgenic plants were successfully applied for milk coagulation experiments, demonstrating the production of functional prochymosin in transgenic lines. In conclusion, here, we report successful expression of functional chymosin in tobacco plants from a novel synthetic version of the bovine prochymosin gene. Our experimental data support that plants could serve as a reliable source for safe and cost-effective production of recombinant chymosin enzyme for industrial usage.