Abstract
Bacteria that exhibit ionic-liquid (IL) tolerance are useful in chemical industries using renewable carbon sources pre-treated by ILs to produce biofuels and fine chemicals. An IL, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), has a remarkable ability to solubilize wood components, whereas [BMIM]Cl inhibits the growth of various bacterial hosts useful for bioconversion. We previously isolated a 10% [BMIM]Cl-tolerant bacterium Bacillus amyloliquefaciens CMW1. Here we report novel mechanisms of tolerance to [BMIM]Cl in strain CMW1 and a novel major facilitator superfamily transporter coded by an ionic-liquid tolerance (ILT) gene. First, using CMW1 cells grown in the presence or absence of 10% [BMIM]Cl, whole-transcriptome analysis and differentially expressed gene analysis were performed. Probable mechanisms of tolerance to [BMIM]Cl include the uptake of osmoprotectants from the culture medium toward CMW1 cells and the export of [BMIM] cations that accumulated in CMW1 cells. The finding represents a first step in elucidation of the mechanisms of IL resistance in Gram-positive bacteria. Second, we conferred tolerance to 5% [BMIM]Cl on [BMIM]Cl-susceptible Brevibacillus choshinensis using ILT gene. This finding provides a notable basis for engineering IL-tolerant bacterial hosts that are applicable for the effective and sustainable production of industrially important chemicals.
Disclosure statement
No potential conflict of interest was reported by the authors.
Data availability
The data that support the findings reported in this study are available at https://datadryad.org/stash/dataset/doi:10.5061/dryad.fj6q573st.