Chemists boost biofuel production
2 Oct 2014
Chemical engineers in the US have modified yeast tolerance to enhance biofuel production capacity, new research suggests.
Large concentrations of ethanol can be toxic to the yeast which is used to transform corn and other plant materials into biofuels - thereby limiting the production capacity of many yeast strains used in industry.
“Toxicity is probably the single most important problem in cost-effective biofuels production,” said Massachusetts Institute of Technology (MIT) chemical engineer Gregory Stephanopoulos, who led the study on industrial biofuel production.
“The more we understand about why a molecule is toxic, the more people will attack other, more severe problems of toxicity
MIT chemical engineer Gregory Stephanopoulos
Now, however, Stephanopoulos, alongside a research team at MIT, claims to have identified a new way to boost yeast tolerance to ethanol by altering the composition of the medium in which certain yeasts are grown.
According to researchers, ethanol and other alcohols can disrupt yeast cell membranes, eventually killing the cells.
The MIT team discovered that adding potassium and hydroxide ions to the medium in which yeast grow can help cells compensate for the cellular membrane damage.
In making these changes, the researchers were able to boost yeast’s ethanol production by around 80%.
“The more we understand about why a molecule is toxic, and methods that will make these organisms more tolerant, the more people will get ideas about how to attack other, more severe problems of toxicity,” said Stephanopoulos.
Before yeast begin their work producing ethanol, the starting material, usually corn, must be broken down into glucose.
According to the researchers, a significant feature of the study is that the experiments were conducted at very high concentrations of glucose.
While many studies have examined ways to boost ethanol tolerance at low glucose levels, the MIT team used concentrations of about 300 grams per litre; similar to what would be found in an industrial biofuel fermenter.
“If you really want to be relevant, you’ve got to go to these levels. Otherwise, what you learn at low ethanol levels is not likely to translate to industrial production,” Stephanopoulos said.
