Increasing concerns about dependence on fossil fuels has generated r.pdf
- 1. Increasing concerns about dependence on fossil fuels has generated research and development of renewable fuels, such as ethanol. Ethanol can be produced from grains (for example, corn) or from plant biomass (tree chips and sawdust, composted food waste or paper products). The production of ethanol is an industrial application of fermentation studied in introductory biology laboratories. Using information from your laboratory experiments, propose the components necessary for converting corn to ethanol. (Consider reactants, products, and environmental conditions). Corn plants store energy as starch, which cannot enter the fermentation pathway directly. Based on your knowledge of the molecular structure of starch, include components necessary to convert starch to simple sugars. Solution Ethanol production from corn is a very recent and important bio-chemical process which can be used as an environmental friendly way to generate fuel. The method is simple and requires following inputs: 1. Corn source: Freshly isolted corn bolts are required for the process with sufficient water content. The dried up corn bolts are difficult to hydrolyze by enzymatic actions. 2. Enzymes: Sequential degradation of the corn's carbohydrates and sugar is brought about by activity of various enzymes. Firstly, the corn is milled into smaller pieces in liquid media which is acted upon by enzyme amylase. The amylase enzyme degrades the complex sugars into smaller carbohydrate units which can be further digested by other carbohydrate digesting enzymes. 3. Fermentation: After activity of amylase, yeast mediated fermentaion of corn is performed. This fermentation is performed under controlled environment of oxygen and temperature along with humidity and nutrients. Bio-chemically, the glucose derived from amylase action on the corn is converted into pyruvate while generating 2 molecules of ATP per glucose molecule and generation of two molecules of NADH. This pyruvate can enter glycolysis in the yeast and simultaneously fermented into acetaldehyde and generation of ethanol with consumption of two NADH molecules. Carbon dioxide is released as a by-product. Thus, this explains the utilizty of various enzymes and microbes in ethanol fermentation by yeast to generate ethanol under controlled environment.