Microbes that ferment ethanol from glycerol, a by-product of biodiesel production, could add an economically valuable new ingredient to the biofuel industry, researchers report.
Industrial plants that make biodiesel by processing vegetable oils and animal fats churn out about 10 kilograms of glycerol for every 100 kg of fuel. Increasing biodiesel production has generated a glycerol glut, with much of this previously useful product now going to waste. Its market value has plummeted by 90 percent since 2004.
But certain microbes can anaerobically ferment glycerol into biofuels and other marketable chemicals, say Ramon Gonzalez and his colleagues at Rice University in Houston in the June Current Opinion in Biotechnology.
The researchers tweaked growth conditions for Escherichia coli so that the bacteria efficiently produced ethanol from glycerol in a benchtop fermenter. Although the process is currently about 40 percent slower than yeast fermentatio