Tapped for Carotenoid Production
By Jan Suszkiw
March 29, 2004
A fungus may hold the key to unlocking
new, value-added uses for corn fiber and distiller's dry grains with solubles
(DDGS) the "leftovers" of making ethanol. That's the hope of
Agricultural Research Service
scientists, who modified the fungus Fusarium sporotrichioides with genes
for making lycopene and other carotenoids.
Lycopene, a pigment that makes tomatoes red, is considered a
"nutraceutical" for its purported health benefits. Some research
suggests lycopene helps prevent certain cancers in people who routinely consume
foods containing the carotenoid. Supplements are available for consumers who
can't or don't want to eat these foods, but still desire lycopene's benefits,
notes geneticist Timothy Leathers, at the ARS
National Center for Agricultural
Utilization Research, Peoria, Ill.
In the modified fungus, Leathers sees a potential way to mass-produce
lycopene from ethanol co-products like corn fiber rather than extract and
purify the carotenoid from tomatoes. Corn fiber is ideal because it's abundant
and costs about five cents a pound. The U.S. ethanol industry generates four
million tons of the fiber annually, and sells it as livestock feed to avoid
disposal fees. The same applies for DDGS, notes Leathers, at the ARS center's
Fermentation Biotechnology Research
Proof-of-concept studies at the Peoria center showed that when cultured in
lab flasks, the modified fungus produced 0.5 milligram of lycopene per gram of
dry weight within six days. The plan now is to scale up the studies by
culturing the fungus in fermenters on a growth medium containing the corn fiber
To equip F. sporotrichioides for the job, the team first
"short-circuited" the metabolic pathways by which it makes natural
trichothecene toxins. Then, using a patented recombinant technique (6,372,479),
the team "re-wired" the fungus with new genes for making lycopene.
ARS patented the microbe on Feb. 24 (6,696,282). Leathers' colleagues are James
Jones of Northwestern University and
Thomas Hohn of Syngenta.
Both are former ARS scientists.
ARS is USDA's chief scientific research agency.