Enhancing ethanol production through light-induced discovery and multi-gene engineering of hyper-biofilm Saccharomyces cerevisiae

Biofilm formation in Saccharomyces cerevisiae significantly enhances ethanol production by improving resistance and metabolic activity. Optogenetics, celebrated for its precision and simplicity, has emerged as a powerful tool for microbial regulation. However, the mechanisms by which blue light influences biofilm formation remain poorly understood. This study demonstrates that specific blue light intensities inhibit biofilm formation in S. cerevisiae without compromising cell growth. Further investigation revealed that calcium signaling pathway (CSP) and cyclic adenosine monophosphate-dependent protein kinase A signaling pathway (cAMP-PKA, Abbreviated as PKA) play central roles in mediating this response. Building on these insights, we applied targeted genetic modifications to key genes (TPK1/2 encoding catalytic subunits of PKA, PDE2 encoding cAMP phosphodiesterase, CRZ1 encoding calcineurin-responsive zinc finger transcription factor) to construct a hyper-biofilm strain, 2Δ- + p(T-C). This strain exhibited enhanced biofilm formation, which was leveraged to optimize ethanol production. By the fifth batch, the fermentation period was reduced from 12.0 to 1.5 h, achieving a peak ethanol yield of 24.8 g/L and a productivity rate of 16.5 g/L/h. These findings highlight the synergy of environmental regulation and genetic engineering in advancing industrial ethanol production.