Glycerol is a by-product in the production of biodiesel from plant oils, and it is produced in quantities that are approximately 10% (w/w) of the biodiesel produced. As the demand for biodiesel increases, there are fears that high biodiesel production would result in a "glycerol glut", and problems may arise in glycerol management/disposal. Although glycerol can be used for pharmecutical and other applications, the high volumes of this by-product (generated from biodiesel operations) have prompted research into other resource-recovery strategies. One option is the fermentation of glycerol to ethanol. In this production scenario, two biofuels can be produced: biodiesel (from plant oils), and bioethanol (from the fermentation of the by-product, glycerol). Compared with lignocellulosic feedstocks, the ethanol production from glycerol is considered to be cheaper because no feedstock pretreatment is required. One of the challenges in the fermentation of glycerol to ethanol, however, is finding an efficient microorganism for the process. Korean scientists from the Jeonbuk Branch Institute, Chonnam National University, Chonbuk National University, and the Korea Atomic Energy Research Institute, reported the development of a microbial strain which efficiently produces ethanol from glycerol. They obtained a mutant strain of Klebsiella pneumoniae GEM167, which was obtained by gamma-irradiation of the microorganism. Ethanol production of the mutant strain increased to 21.5 g/L, and this was reported to be the "highest level [of ethanol yield from glycerol fermentation] reported to date". Genetic engineering of the mutant strain further increased the ethanol yield to 25.0 g/L. The results are published in the journal, Bioresource Technology (URL above).