Date Approved

2016

Date Posted

4-27-2016

Degree Type

Open Access Senior Honors Thesis

Department or School

Biology

First Advisor

Daniel Clemans

Second Advisor

Kristin E. Judd

Abstract

Coaggregation has been indicated as a key mechanism in the formation of biofilms. This research sought to characterize the interactions occurring between native gastrointestinal Bacteroides & Parabacteroides and the probiotic strain Lactobacillus rhamnosus GG (LGG) cultured in Todd Hewitt (TH), deMan, Rogosa, and Sharpe (MRS), and Brain Heart Infusion (BHI) using in vitro coaggregation assays. In the coaggregation survey of interactions, a trend of growth medium-dependent coaggregation variability was displayed with LGG grown in TH displaying the widest spectrum of coaggregation with Bacteroides/Parabacteroides strains and narrower spectrum from the other cultures of LGG. By protease inhibition, it was confirmed that the presence of novel adhesin(s) occurs on LGG, mediating coaggregation with moderate strength to a variety of Bacteroides & Parabacteroides strains abundant in the large intestine, including selective interactions with capsule-deficient mutants of B. thetaiotaomicron VPI-5482. In the case of LGG grown in MRS, bimodal adhesin interaction with involvement of Bacteroides/Parabacteroides partners was observed. These interactions were not reversed by the addition of a variety of simple sugars, providing no support for the presence of a lectin-like adhesion on LGG, and thus the affinity of the adhesin(s) involved remains to be characterized.

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