Bio-valorization of Dairy Whey for Bioethanol by Stress-Tolerant Yeast

Ethanol as a fuel has been used during the course of mankind industrial and social history. But due to the tax burden on ethanol and the cheaper cost of kerosene oil, it quickly substitutes ethanol. Ethanol is obtained by anaerobic fermentation by preferably yeast using sugars. Various different agro-industrial residues were used for the production of bioethanol at pilot scale. One important substrate, i.e., lactose, mainly present in milk and recognized as a huge unexplored waste remains from all the different kinds of cheese produced worldwide by the dairy processing sector. The global production of cheese whey is over 160 million tons production per year, showing a 1–2% annual growth rate. During fermentation of sugar to ethanol, yeast strains have to be capable to endure certain physiological stress and still growing actively at economically and in principle suitable standards. The future of ethanol production using stress-tolerant yeast to make the process more economically viable is very important. Utilization of high gravity substrate like concentrated cheese whey required the yeast strains with better and higher osmotolerant strains.