Date of this Version
Oney, E. 2019. A Comparative Analysis of the Fermentation Capabilities of Various Bifidobacterium Strains. Undergraduate Honors Thesis. University of Nebraska-Lincoln.
Bifidobacterium is a genus of anaerobic bacteria that are commonly found to inhabit the gastrointestinal tract of many members of the animal kingdom. These microorganisms are adapted to obtain their carbon from the breakdown of complex carbohydrates. Marmosets, a mammal whose gut microbiome is inhabited by high levels of Bifidobacteria, consume gum Arabic as a major part of their diet. The purpose of this experiment is to determine whether Bifidobacterium strains isolated from the guts of marmosets are able to degrade and ferment this complex carbohydrate or one of its main constituents, arabinose. This was accomplished by inoculating isolates of Bifidobacterium species into tubes containing basal MRS medium supplemented with gum Arabic or arabinose and monitoring pH (color change) over time. Each of the 12 marmoset-derived isolates were tested in liquid media containing either 5% arabinose, 3% gum Arabic, or 1% gum Arabic. A positive phenotype indicating fermentation of the substrate was visualized by a shift in the media’s color from purple to yellow. The fermentative capabilities of the marmoset strains were then compared to 13 other Bifidobacterium strains that were isolated from other mammals such as rats, pigs, and humans. Two strains from each group expressed a negative phenotype for arabinose, while all other strains were positive. In the marmoset group, 6 of the strains expressed positive phenotypes for the 1% gum and 8 were positive for the 3% concentration. The group of strains from non-marmoset origins sported 5 positive phenotypes for the 1% concentration of gum Arabic, while 6 strains tested positive for the 3% concentration.