Chemist Badal Saha (left) discusses control parameters of mannitol production by fermentation with technician Greg Kennedy (center) and student aide Ohiole Ake. Click the image for more information about it.

Bacteria-based Production Method Patented

By Jan Suszkiw
March 30, 2005

Look on a package of gum and you'll probably notice the word mannitol. Scientifically described as a sugar alcohol, mannitol is a minty-tasting ingredient found in many foods and boasts fewer calories than table sugar.

Though made by some plants and algae, mannitol is commercially produced by chemical means. In February, however, the Agricultural Research Service (ARS) obtained a patent (US 6,855,526, B2) on a method that weds nature with modern technology. ARS chemist Badal Saha calls his method "biobased" because it involves feeding high-fructose corn syrup to the bacterial species Lactobacillus intermedius in a deep-tank fermentor. There, over several hours' time, the bacteria convert 72 percent of the syrup into mannitol.

Mannitol, to L. intermedius, is little more than a metabolic waste product. But to food processors, mannitol is a valuable bodying agent, preservative and diabetic-friendly sweetener, according to Saha, with the ARS National Center for Agricultural Utilization Research at Peoria, Ill.

Mannitol also has pharmaceutical and medical uses, such as an osmotic diuretic and a hypertension treatment. Manufacturers traditionally produce mannitol by subjecting a 50-50 mixture of fructose and glucose to a nickel catalyst and high-pressure hydrogenation. Besides producing chemical wastes, the process is time-consuming and converts only 25 percent of these sugars to mannitol, sold for around $3.25 a pound.

Saha's Lactobacillus bacterium uses powerful enzymes to do this far more efficiently--and not just with fructose. In Saha's trials at the ARS center's Fermentation Biotechnology Research Unit, the bacterium also produced mannitol from sucrose and other sugars.

Since 2002, Saha has collaborated with zuChem, Inc., of Chicago, Ill., to scale-up and refine the approach under a cooperative research and development agreement. Last fall, zuChem successfully petitioned the Food and Drug Administration to approve mannitol produced by microbial fermentation. Saha's research reflects the ARS center's overarching mission of creating new, value-added markets for agricultural commodities, especially from corn and soybeans.

ARS is the U.S. Department of Agriculture's chief scientific research agency.