Disruption of agr quorum sensing for enhancing biofilm formation and butanol production in Clostridium acetobutylicum

Clostridium acetobutylicum has been extensively exploited as a crucial platform for the production of biofuels and bulk chemicals and its biofilm could significantly enhance the productivity. Here, we characterized biofilms and associated phenotypes to assess the impact of agr in mutants. The agrB mutant exhibited the formation of more robust biofilms owing to the alterations in motility, chemotaxis and adhesion. Additionally, a more efficient butanol metabolism was observed, resulting in the butanol accumulation of 11.3 g/L. The exogenous supplementation of methyl viologen modified the carbon flux, achieving a maximum butanol production of 12.8 g/L and a butanol ratio of 77.1 %. Consequently, a biofilm-based fermentation was conducted, leading to an increase in butanol production from 8.7 g/L to 14.3 g/L and an enhancement in productivity from 0.14 g/L/h to 0.40 g/L/h, indicating agrB mutant held significant potential for butanol production in biofilm-based immobilized fermentation. This study provided valuable insights into the regulation of biofilm formation and solventogenesis by agr in Clostridium species, paving the way for further engineering of biofilm-based industrial processes.