Yeasts as production hosts for bulk chemicals

Industrial biotechnology is increasingly important for our society in providing sustainable technologies in production of fuels, chemicals and materials. Use of plant carbohydrates provides a replacement for oil-based raw materials with corresponding reductions in carbon dioxide release to the atmosphere. Yeasts, Saccharomyces cerevisiae in particular, have a long record as robust hosts for large scale industrial production. Bulk products such as bioethanol are produced in increasing amounts. For the processes to be ecoefficient lignocellulosic waste needs to be used, including hemicellulose-derived pentose sugars (e.g. xylose) for production of bioethanol or other products such as xylitol, lactic acid or other organic acids that can serve as precursors for biopolymer production. Substantial metabolic engineering efforts have been carried out to engineer yeasts for efficient pentose fermentation. Non-conventional yeasts can also turn out to be attractive production hosts due to their broader substrate range or tolerance towards higher temperatures and low pH. Furthermore, research towards simultaneous production of (hemi)cellulolytic enzymes and chemicals in yeast paves the way towards consolidated processes. To compete with petrochemistry bioprocesses need to be highly efficient. The full use of genome information and systems biology combined with classical mutagenesis and evolutionary engineering are needed in strain engineering.