Plastic may compete with paper in the grocery line, but
it doesn’t have to compete with the world’s food supply, according to Univ. of Florida researchers.
They’ve developed a way to produce plastic that doesn’t
use valuable natural resources, such as food or fuel, for raw materials.
The new method uses a strain of bacteria to create
bioplastic from discarded plant material, such as yard waste.
Bioplastic, or plastic from renewable resources, is
produced when an organism such as a bacterium creates lactic acid while
fermenting carbohydrates. The lactic acid can then be converted into long
chains of molecules to form plastic.
Current bioplastic production uses food carbohydrates,
such as cane sugar or corn starch, as raw materials. Traditional plastic
production requires petroleum.
Keelnatham Shanmugam, a UF microbiology and cell science
professor, Lonnie Ingram, a distinguished professor in microbiology and cell
science, and their co-workers made the development. Their research is published
in the Journal of Industrial Microbiology
and Biotechnology.
“As we start using more and more bioplastics, we are
infringing upon the use of food material,” said Shanmugam. “We’d like to switch
away from food-based carbohydrates to non-food-based carbohydrates for
producing plastics.”
Using discarded plant material to produce plastic helps
keep commodity prices down. The plastic produced from the process is both
biodegradable and recyclable, Shanmugam said.
In the study, the researchers tested the bacterium—Bacillus coagulans strain 36D1—for its
ability to produce lactic acid in a variety of conditions typical of bioplastic
production. The bacterium was collected from a geyser in Calistoga, Calif.,
which was one of the many places the researchers sampled for bacteria.
Previous attempts to produce lactic acid from discarded
plant materials using microorganisms have not yielded enough lactic acid and
weren’t cost effective.
However, Shanmugam and Ingram found that by adding
calcium carbonate to the process, they achieved lactic acid yields as high as
those achieved by organisms that fermented food carbohydrates.
Additionally, the heat-tolerant bacterial strain also
cut production costs significantly by allowing the process to run at a higher
temperature, which reduced the amount of expensive, plant-digesting enzymes
required by up to four times.
Cost savings are also achieved by eliminating the need
for food carbohydrates as raw materials since discarded plant waste is less
expensive. For example, using straw as a raw material is 13 times less
expensive than sugar and five times less expensive than corn or wheat.
Mark Ou, a UF biological scientist and the study’s lead
author, said increases in oil prices over the last several years have led to
more interest in petroleum alternatives for plastic production.
“If we can save some of our oil and turn our plants into
our plastic cups and packaging, then we can increase our national security by
reducing our dependence on foreign oil,” Ou said.
