Choline-based ionic liquids for planktonic and biofilm growth control of Bacillus cereus and Pseudomonas fluorescens

Choline-based ionic liquids (ILs) emerge as promising alternatives for microbial growth control due to their relevant antimicrobial activity, in addition to eco-, bio-friendly and cost-effective properties. Nevertheless, data on choline-based ILs antibiofilm activity is still scarce. In this study, two choline-based ILs: choline alaninate - [Ch] [Ala] and choline glycinate - [Ch] [Gly] were evaluated in terms of antimicrobial and antibiofilm activity against Bacillus cereus and Pseudomonas fluorescens. Two quaternary ammonium compounds (QACs): benzalkonium chloride - BAC and cetyltrimethylammonium chloride - CTAC were used for comparison. [Ch] [Ala] and [Ch] [Gly] demonstrated antibacterial activity against B. cereus and P. fluorescens. However, their activity was lower than that of BAC and CTAC. The mode of action of the selected ILs on planktonic cells was found to be related to the dysfunction and disruption of the bacterial outer layer(s). Moreover, the ILs demonstrated an important action in biofilm control, causing significant removal of biomass (90%) and reduction of culturable population (3 log CFU/cm(2)). The dual combinations between the ILs and QACs caused additive antibiofilm effects. This study demonstrates the potential of choline-based ILs to be used alone or in combination with QACs, as a sustainable alternative for biofilm control. (C) 2021 Elsevier B.V. All rights reserved.