Technical note: A method for isolating glycogen granules from ruminal protozoa for further characterization

Authors: Hall, Mary Beth

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2015
Publication Date: 3/1/2016
Publication URL: https://handle.nal.usda.gov/10113/62660
Citation: Hall, M. 2016. Technical note: A method for isolating glycogen granules from ruminal protozoa for further characterization. Journal of Dairy Science. 99:1956-1958.

Interpretive Summary: In animals with a rumen, microbes aid with digestion by fermenting and degrading feedstuffs. Ruminal protozoa, one type of microbe found in the rumen, can convert a significant portion of dietary sugars and other carbohydrates into glycogen. Production of glycogen changes the rate of carbohydrate fermentation in the rumen and the type of nutrients that are available to the cow. Evaluations of physical, compositional, and digestion characteristics of protozoal glycogen are best performed on pure glycogen to avoid interference from other protozoal cell components. We developed a method to isolate protozoal glycogen granules based on sedimentation and separation of glycogen-laden protozoa. The simple method will allow researchers to isolate protozoal glycogen in order to assess its nutritional qualities. Such research will lead to a better understanding of the nutritional needs of dairy cattle in order to more efficiently produce food and maintain good environmental quality for our nation.

Technical Abstract: Evaluation of physical, compositional, and digestion characteristics of protozoal glycogen is best performed on a pure substrate in order to avoid interference from other cell components. A method for isolating protozoal glycogen without use of detergents was developed. Rumen inoculum was incubated anerobically in vitro with glucose. Glycogen-laden protozoa produced in the fermentation were allowed to sediment in a separatory funnel and were decanted. The protozoa were processed through repeated centrifugations and sonication to isolate glycogen granules free of feed and cellular debris. The final water-insoluble lyophilized product was analyzed as 98.3% alpha-glucan with rare starch granules. This isolated material is suitable for evaluating nutritionally and analytically relevant characteristics of protozoal glycogen granules.