|Thomas, S - CORNELL UNIVERSITY|
Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2004
Publication Date: March 1, 2004
Citation: Thomas, S., Russell, J.B. 2004. The effect of cellobiose, glucose and cellulose on the survival of fibrobacter succinogenes a3c cultures grown under ammonia limitation. Current Microbiology. 88:219-223. Interpretive Summary: Cellulose is the most abundant carbohydrate in nature, but mammals lack enzymes that can degrade this material. Ruminants developed the capacity to digest cellulose by exploiting a symbiotic relationship with cellulolytic ruminal bacteria. The rumen normally operate as a carbohydrate-limited system, but ammonia and nitrogen sources can also be limiting. F. succinogenes S85 digests cellulose at a rapid rate, but previous work indicate that cellobiose, an end-product of cellulose digestion, could kill this bacterium when ammonia was limiting. In this manuscript we examined the effect of another soluble carbohydrate (glucose) and cellulose on the viability of F. succinogenes. Results indicated that glucose also killed F. succinogenes but cellulose did not. Research of ruminal cellulose digestion has the potential to enhance cattle productivity and decrease the cost of cattle production.
Technical Abstract: The ruminal, cellulolytic bacterium, Fibrobacter succinogenes A3C, grew rapidly on cellulose, cellobiose or glucose, but it could not withstand long periods of energy source starvation. If ammonia was limiting and either cellobiose or glucose was in excess, the viability declined even faster. The carbohydrate-excess, ammonia-limited cultures did not spill energy, but they accumulated large amounts of cellular polysaccharide. Cultures that were carbohydrate-limited had approximately 4 nmol ATP mg cell protein-1, but ATP could not be detected in cultures that had an excess of soluble carbohydrates. However, if F. succinogenes A3C was provided with excess-cellulose and ammonia was limiting, ATP did not decline and the cultures digested the cellulose soon after additional nitrogen sources were added. Based on these results, it appears that excess-soluble carbohydrates can promote the death of F. succinogenes, but cellulose does not.