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United States Department of Agriculture

Agricultural Research Service

Title: Isolation and Characterization of Microorganisms with Alternan Hydrolytic Activity

Authors
item Wyckoff, Herbert
item Cote, Gregory
item Biely, Peter - SLOVAK ACADEMY

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 1995
Publication Date: N/A

Interpretive Summary: An ongoing trend in food product formulation is to develop food items with fewer calories. Many food companies do this by using artificial or alternative sweeteners. Most of these sweeteners are added in smaller amounts than traditional sweeteners, and the loss in volume is usually replaced with bulking agents. A commonly used bulking agent is gum arabic. Gum arabic supplies can be unpredictable and prices may vary significantly because it is imported from the Middle East. A promising replacement for gum arabic is alternan, a polysaccharide produced by microorganisms, which may be grown on domestic agricultural commodities such as beet or cane sugar and corn milling byproducts. To be most useful as a bulking agent, alternan must be modified by breaking into smaller particles. The purpose of this research was to isolate bacteria that produce enzymes which separate the polymer alternan. Using a new screening procedure, we isolated from soil and plant material, several bacterial strains which grew on the microbial polysaccharide alternan. These newly isolated bacteria produced enzymes that broke down alternan into the types of products that could be useful as bulking agents for use in new low calorie foods.

Technical Abstract: Alternan is an unusual alpha-D-glucan containing alternating (1-3), (1-6) linkages that exhibits remarkable resistance to enzymatic hydrolysis. The commercial potential of the polysaccharide may be enhanced by the ability to economically modify the native form into fractions of varying molecular weight. By employing isolation procedures using covalently dyed alternan as the substrate, several bacterial isolates that produced endohydrolytic activity were obtained in pure culture. The activity was confirmed by decreases in viscosity and by direct examination of the hydrolysis products using thin layer chromatography. Analysis of the hydrolysis products established that all isolates produced enzymes with identical alternan depolymerizing activity. All alternanase activity was shown to be extracellularly located. A single strain exhibited constitutive production of alternanase while all other isolates required the presence of alternan in the growth media for enzyme production. All isolates were phenotypically similar, produced heat resistant spores and were tentatively identified as members of the genus Bacillus.

Last Modified: 12/22/2014
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