Tobacco plants produce abundant biomass in more than 100 countries and could -- with certain genetic modifications -- be used to produce abundant biofuels, researchers say.
Researchers at the Biotechnology Foundation Laboratories of Thomas Jefferson University in Philadelphia, have successfully tested genetic manipulations to increase oil accumulation in the leaves of tobacco plants, according to a paper published online in Plant Biotechnology Journal.
"In the search for alternative biofuel plant resources, tobacco has been largely overlooked as it is considered primarily as an expensive crop grown for smoking," researchers Vyacheslav Andrianov and Nikolai Borisjuk wrote.
"When grown for energy production instead of smoking, tobacco can generate a large amount of inexpensive biomass more efficiently than almost any other agricultural crop," the researchers wrote.
In most plants, biofuel oil is extracted from the seeds rather than the leaves or stems. But while tobacco plants produce very oily seeds, they do not make large numbers of them, the researchers said.
To make tobacco plants more attractive as a feedstock, they tested two genetic modifications to shift oil production and accumulation into the tobacco plant's large and plentiful leaves.
By engineering plants to overexpress one gene, the researchers doubled the fatty acids extracted from a plant to 5.8 percent of the dry biomass weight for one tobacco strain and 6 percent for another.
A second genetic change made the plant accumulate up to 6.8 percent per dry weight of extracted fatty acids, they reported.
The researchers said further experimentation should be done to test whether making both of the changes in a single plant yields the full cumulative increase.
But if either of those gains could be secured at a large scale, tobacco could become a useful biofuel feedstock, they said.
Citing a 2008 study, the researchers said that if one assumed a conservative harvest of 170 metric tons per hectare for about 20 tons of dry biomass, engineered tobacco plants with 6 percent fatty acid by dry weight would produce at least twice as much biodiesel as a hectare of soybeans.
Extracting oil from the green parts of a plant is not as well understood as pressing it out of seeds, the authors noted, presenting a hurdle to commercial production. But the process could be expected to yield glycerin as a valuable byproduct, and the pressed leaves could be fermented to make ethanol, as well, they said.
"By generating both biofuel oil and ethanol, tobacco has the potential to produce more energy per hectare than any other non-food crop," they conclude.
Reprinted from Greenwire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500