Optogenetic Fine-Tuning of Sus scrofa Basic Fibroblast Growth Factor Expression in Escherichia coli

Basic fibroblast growth factor (bFGF) is a crucial protein with diverse applications in biotechnology and medicine. This study aims to investigate the use of EL222-based optogenetic control systems to fine-tune the expression of porcine (Sus scrofa) bFGF in Escherichia coli. The bioactivity and the productivity of blue light-induced bFGF were demonstrated to be comparable to those achieved using a conventional T7-expression system. Secondly, through systematic optimization of regulatory elements, optimal expression of bFGF was achieved using a medium-strength promoter for EL222 expression, a strong RBS upstream of the bFGF gene, and an optimized C120 configuration within the blue light-inducible promoter. Moreover, various parameters of blue light illumination during fermentation were investigated, including initial cell density, light intensity, illumination duration, and pulsed illumination patterns. The results identified optimal conditions for maximizing bFGF yield in E. coli, specifically an initial OD600 of 0.6, 800 lux blue light intensity, and 8 h total illumination in a 2 h on/off pattern. Overall, this successful implementation of optogenetically controlled bFGF expression in E. coli serves as a proof-of-concept for light-responsive systems in industrial biotechnology, highlighting the potential of optogenetic control for biologically active protein production.