In a recently paper published in the Journal of Bacteriology scientists outlined a process to manipulate the Imidazolium Ionic Liquid tolerance which can be useful to overcome a key gap in biofuel and biochemical production processes.
Although plant cell walls contain renewable and limitless supply of sugars, retrieving these sugars aren’t easy. For instance, Imidazolium Ionic Liquid (IIL) solvents are one of the best sources for extracting sugars from plants but, these sugars are contaminated with residual IILs that inhibit growth in bacteria and yeast, thus blocking biochemical production of these organisms.
However, Lawrence Livermore National Laboratory (LLNL) scientists and collaborators at the Joint BioEnergy Institute have identified a molecular mechanism in bacteria that can be manipulated to promote IIL tolerance.
“Ionic liquid toxicity is a critical roadblock in many industrial biosynthetic pathways,” said LLNL biologist Michael Thelen, lead author of the paper. “We were able to find microbes that are resistant to the cytotoxic effects.”
During the course of their study, the researchers used four bacillus strains that were isolated from compost along with a mutant E. coli bacterium. The scientists found that two of the strains and the E. coli mutant can withstand the high levels of widely used IILs.
Afterwards, Douglas Higgins tried to understand how the bacteria achieves this process. Interestingly, he identified a membrane transporter that is responsible for exporting the toxic IIL. Moreover, he found two instances in which the pump gene contained alterations in the RNA sequence of regulatory guanidine riboswitch. Guanidine is a toxic byproduct of normal biological processes and cells need to get rid of before accumulating it. In order to do so, the normal riboswitch interacts with guanidine and undergoes a conformational change that causes the pump to switch on and protect cells resistant to IILs.
With their latest findings, the researchers expect that they will be able to identify genetic engineering strategies that will improve conversion of cellulosic sugars into biofuels and biochemicals in processes.