Introduction

Society is facing a number of key socio-economic and environmental challenges: global warming, extinction of species in key ecosystems, malnutrition, shortages of water and other natural resources. All of these are human-made problems, and they require innovative solutions. While precious natural resources continue to dwindle, the number of consumers and polluters is growing. A major challenge for the future is development of products that are less hazardous, pollute less and require less energy. It is here that enzymes can make an impact on the future of society. In 1878, Kühne coined the term ‘enzyme’ from the Greek enzumos, which refers to the leavening of bread by yeast. However, the modern term refers to biological catalysts in the form of globular proteins that facilitate chemical reactions in the cells of all living organisms. Enzyme-catalysed reactions take place under relatively mild and ecologically friendly conditions, are highly specific and greatly accelerate the rates of the reactions in which they participate. Enzymes make better use of raw materials, save water and energy, and often replace toxic chemical processes. For example, the enzymes from bacteria and fungi in forest litter are primarily responsible for the breakdown of decaying plant biomass and, thus, they are critical in the recycling process we recognise as the global carbon cycle. These microbial enzymes may one day be harnessed to convert waste plant materials, such as corn stover, straw and grasses, into fuel and simple carbon compounds used for the synthesis of chemical and pharmaceutical intermediates, thereby decreasing our dependence on petroleum-based carbon.