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Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/20/1994
Publication Date: N/A
Citation: Interpretive Summary: A number of studies have been conducted which add microorganisms to the rumen or intestinal tract of animals. The objective is to produce a beneficial fermentation in the gastrointestinal tract. One successful study has been the transfer of ruminal fluid from Hawaiian goats to Australian cattle to overcome the toxic component in the Leucaena plant. In our study we tried to increase the degradation of fiber in the rumen and in the intestinal tract of pigs by adding a large dose of a very active fiber degrading bacterium, originally isolated from the rumen of a bison and a steer. The ruminal contents were completely removed from three cows. Buffer solution and the bacterium were added. The bacterium was the largest population of bacteria for five hours after being added. After 24 hours the number of the fiber degrading bacterium added was less than the normally found fiber degrading bacteria in the rumen. After 48 hours the added bacterium was not detected in the rumens. The same bacterium was infused as a large dose into the intestine of seven pigs. It could not be recovered in fecal samples at 24, 48 or 72 hours after infusion. The unsuccessful introduction of this ruminal bacterium into the rumen or intestinal tract of pigs emphasizes the competition that must be overcome to successfully add microorganisms to the intestinal tract or rumen. Genetically modified microorganisms will need to be highly engineered to give them a selective advantage to compete in these ecosystems.
Technical Abstract: Studies were conducted to determine if intestinal cellulolytic bacteria could be introduced into the rumen or pig large intestine. In the first study, the ruminal fluid of three cows was evacuated and replaced with 20 l of buffer and 6 l of the ruminal or swine cellulolytic organism, Clostridium longisporum or C. herbivorans, respectively. The introduced organisms were the predominant cellulolytic bacterium in the fluid (> 10**7 cells ml**-1) at 0 h. C. longisporum was still the predominant cellulolytic organism after 5 h, 0.55 x 10**7 cells ml**-1; however, after 24 h it decreased to 0.05 x 10**7 compared to 2.8 x 10**7 cells ml**-1 for the total cellulolytic organisms. After 48 h, C. longisporum was no longer detectable. C. herbivorans was identified in only one of the three cows after 24 h, and was not detected at 72 h. In a second study, when C. longisporum (50 ml, 10**7 cells ml**-1) was infused into the terminal ileum of seven pigs, it was not recovered when fecal samples were evaluated at 24, 48 or 72 h after infusion. These studies emphasize the competition that must be overcome to successfully introduce organisms into an intestinal ecosystem. Furthermore, these studies suggest that C. longisporum is a transient organism in the rumen; however, C. herbivorans is part of the normal intestinal flora of pigs and may play a major role in fiber degradation.