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Despite the bactericidal effects of ethanol, acidifying effects of fermentation, and low oxygen conditions of industrial alcohol production, bacteria that undergo lactic acid fermentation can contaminate such facilities because lactic acid has a low pKa of 3.86 to avoid decoupling the pH membrane gradient that supports regulated transport. [7]
The dominant ethanol feedstock in warmer regions is sugarcane. [8] In temperate regions, corn or sugar beets are used. [8] [9] In the United States, the main feedstock for the production of ethanol is currently corn. [8] Approximately 2.8 gallons of ethanol are produced from one bushel of corn (0.42 liter per kilogram).
Ethanol is the most commonly used biofuel and can be produced on large scale via fermentation. The maximum theoretical yield for the production of ethanol was achieved around 20 years. [14] [15] A plasmid that carried the pyruvate decarboxylase and alcohol dehydrogenase genes from the bacteria Z. mobilis was used by scientists.
Ethanol from coal is the ethanol produced using coal as its carbon source. The anaerobic bacterium Clostridium ljungdahlii produces ethanol and acetic acid from CO, CO 2, and H 2 in synthesis gas. Early studies with C. ljungdahlii showed that relatively high concentrations of ethanol were produced. This process involves three main steps:
The production of butanol by biological means was first performed by Louis Pasteur in 1861. [5] In 1905, Austrian biochemist Franz Schardinger found that acetone could similarly be produced. [5] In 1910 Auguste Fernbach (1860–1939) developed a bacterial fermentation process using potato starch as a feedstock in the production of butanol. [6]
Ethanol production depends on development of cellulosic technology. Breeding efforts underway to increase yields. Higher biomass production is possible with mixed species of perennial grasses. Poplar: 3700–6000 L/ha, 400–640 gal/acre 51%–100% 3 9 [98] Fast-growing tree. Ethanol production depends on development of cellulosic technology.
At lower quantities of production, Wang finds it appropriate to credit corn ethanol based on the input energy requirement of the feed product or good that the ethanol by-product displaces. [8] In 2004, a USDA report found that co-products accounting made the difference between energy ratios of 1.06 and 1.67.
In the production of bio-ethanol, the medium may consist mostly of whatever inexpensive carbon source is available. [ citation needed ] Carbon sources are typically sugars or other carbohydrates, although in the case of substrate transformations (such as the production of vinegar) the carbon source may be an alcohol or something else altogether.