(American Society for Microbiology) -- An extract from the roots of the licorice plant is active against a number of microorganisms that can cause food contamination and may be an effective natural alternative to chemical preservatives. Researchers from the Higashimaru Shoyu Company in Japan report their findings in the May 2002 issue of the journal Antimicrobial Agents and Chemotherapy.

Licorice, the root and rhizome of the Glycyrrhiza species, has been used for centuries as a medicine because of its wide-ranging therapeutic properties and recent chemical analyses have found a wide variety of bioactive compounds in licorice. The researchers tested the extract, a compound known as licochalcone A, on 17 food spoilage microorganisms. They found that while the extract was not effective against fungi and gram-negative bacteria, it was effective against all gram-positive bacteria, especially the spore-forming Bacillus species.

"A recent trend in food processing is to avoid the use of chemical preservatives; thus, natural antimicrobial alternatives are required," say the researchers. "In the present study, salt-, heat-, and protease-resistant licochalcone A was suggested to be a promising lead compound for the development of agents against spore-forming bacteria."