Starch Granule Utilization by Streptococcus Bovis and Ruminobacter Amylophilus
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Ruminant animals depend on microbial activity to ferment polysaccharides to organic acids which the ruminant can absorb. Rapidly fermented starch comprises the grains fed to cattle in intensive livestock production. The result of this rapid digestion is rapid production organic acids, which can be produced too rapidly ror the ruminant to absorb or buffer. The build up of lactic acid in the rumen is a condition called acute acidosis, which is characterized by low rumen and blood pH, reduced food intake, and respiratory distress. Methods were developed to monitor insoluble starch degradation by the anaerobic ruminal bacteria, Streptococcus bovis and Ruminobacter amylophilus. Conditions were established in which these organisms could be inoculated, grown, and harvested. Experiments were conducted with these organisms to study the roles of adherence, digestion and extracellular amylases in utilization of starch. S. bovis did not exhibit adherence, but digested starch granules, while R. amylophilus adhered to starch granules but did not to digest them. Because of this, R. amylophilus was not included in the remaining studies. The need for extracellular amylases by S. bovis was studied by incubating maltose-grown cells and soluble starch-grown cells in 3% starch granule media. Some of the samples were treated with chloramphenicol and rifampin, which inhibit protein production. Although the experiment was a pilot and needs repetition, cells without extracellular amylases present continued to digest starch, leading. to the conclusion that extracellular amylases are not necessary for starch degradation.