Genetically engineering microbes to produce second-generation biofuels

Article By:

Pierce, Marcia M. Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky.

Last reviewed:November 2017

DOI:https://doi.org/10.1036/1097-8542.YB170501

Fuels that are produced biologically are known as biofuels. For example, anaerobic fermentation is one methodology that is used to convert biomass left over from agricultural production into energy. In contrast, traditional fuels are obtained from geologic processes that occurred over millions of years. Biofuels are renewable forms of fuel, whereas fossil fuels occur as the result of the decomposition of dead plant materials, taking millions of years to form. These fossil fuels, including coal, petroleum, and natural gas, cannot be renewed. Biofuels, though, can be either first- or second-generation fuels, based on the type of biomass used to produce the fuel. First-generation biofuels are made from sugars and vegetable oils extracted from crops grown specifically for that purpose. Ethanol extracted from corn crops is an example of a commonly used first-generation biofuel (Fig. 1). Second-generation biofuels are made from materials that are more difficult to convert. These materials include woody crops, which contain cellulose, or agricultural residues or waste. Because agricultural wastes are an untapped by-product or resource, scientists are working to identify novel microorganisms and enzymes that can increase the ability to extract fuels from these nonfood plant stocks. See also: Biochemical engineering; Biomass; Biosynthesis; Biotechnology; Cellulose; Energy sources; Enzyme; Ethyl alcohol; Fat and oil; Fermentation; Microbial ecology; Microbial interactions; Microbiology; Renewable resources

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