Directed Evolution of Pectin Methylesterase to Higher Activity

Abstract

Biofuels have become an increasing interest over the last decade as the cost of fuel has continued to fluctuate and the sources of fossil fuels have been slowly depleting (Faaij 2006). In general, biofuels, also known as alternative fuel, are renewable energy sources that are produced from raw biological resources referred to as biomass (Demirbas 2009). Several advantages to biofuels include the high availability of biomass, the reduction in greenhouse gas emissions, and the elimination of dependence on fossil fuels found in other countries. Unlike fossil fuels, biofuels are renewable energy sources meaning they can be produced or replenished within a short period of time (Ragauskas 2006). Fossil fuels, such as crude oil that is formed from the buried remains of plants and animals that lived millions of years ago, will soon run out at the rate at which the fossil fuels are currently being consumed. On the other hand, biofuels are produced at a much faster rate and the supply of biomass feedstocks is not fixed. These feedstocks can include plant and algal material such as food and agricultural waste as well as municipal solid waste and yard clippings. These wastes, that would normally be unused, can now be used to generate energy, thus recycling waste that would be otherwise unusable. In addition, energy biomass crops such as switchgrass, energy beets, or poplars are being considered as other potential feedstocks (Demirbas 2009).