German scientists have developed a technique to produce the low calorie sweetener erythritol from straw using a new genetically modified fungus.
The new production method, published in AMB Express, reveals a new way to produce the calorie-free sweetener – which is currently produced using yeasts and glucose from wheat or corn starch.
However, the team led by Dr Astrid Mach-Aigner from the Vienna University of Technology, have now developed a method to produce the sweetener from ordinary straw with the help of a mould fungus.
"We knew that the mould fungus Trichoderma reesei is in principle capable of producing erythritol, but usually only in tiny quantities", said Professor Robert Mach, who also worked on the study. "By genetically modifying it, we managed to stimulate the production of an enzyme, which enables the large-scale production of the sweetener."
Experiments using the genetically modified fungus (rather than yeasts) have been a ‘big success’, said the team – who now plan to optimise the procedure for industrial use.
"We have proven that the new production method works", Mach added. "Now we want to improve it together with our industry partners so that it can be used for large-scale production."
The scientists used wheat straw pre-treated with an alkaline organic solvent to remove the lignin (polymer layer) to a residual concentration of about 1% (w/w) making it easier for the fungus to access the cellulose.
The treated straw was then exposed to the GM fungus strains - with some cultivated in shake flasks and others in bioreactors.
Results showed the modified fungus increased erythritol production ten-fold.
“We demonstrated that the production of erythritol on the renewable, non-food substrate wheat straw, using T. reesei is possible,” the report said.
“The alkaline organosolve pre-treatment process used for the wheat straw is compatible for subsequent fungal growth and provides an easily utilizible substrate.”
Source: AMB Express
Volume 4, Issue 34, doi: 10.1186/s13568-014-0034-y
‘Erythritol production on wheat straw using Trichoderma reesei’
Authors: Birgit Jovanović, Robert L Mach,a Astrid R Mach-Aigner