Harnessing quorum sensing to enhance butanol production and tolerance in Clostridium acetobutylicum

Abstract

Butanol production is hindered by butanol toxicity on solventogenic clostridia during acetone-butanol-ethanol fermentation. Despite numerous efforts made on strain engineering to enhance butanol tolerance, effectively improving butanol production remains challenging. Here, we investigated the regulatory roles of the AgrCA two-component system involved in quorum sensing in Clostridium acetobutylicum. Through modification of agrC and agrA, we found that overexpression of agrCA increased butanol production by 12.8 % while maintaining vegetative cell morphology during free-cell fermentation. The concentration that inhibited cell growth by 50 % increased from 9.0 to 11.6 g/L, demonstrating a 28.9 % improvement in butanol tolerance. Moreover, overexpressing agrCA promoted biofilm formation in immobilized-cell fermentation, resulting in 17.2 g/L butanol with a productivity of 0.48 g/L/h, compared to 12.5 g/L and 0.26 g/L/h in the control strain, respectively. These findings highlight the pleiotropic regulation of AgrCA in C. acetobutylicum, providing a promising strategy for enhancing microbial production via quorum sensing manipulation.