| Increasing prevalence of multidrug-resistance bacteria from extensive antibiotic usage and shortages of new classes of antibiotics have created urgent needs for alternative prevention and treatment options for infections. Based on the hypothesis that lactic acid bacteria (LAB) and their metabolites can prevent and treat infections, this thesis aims to demonstrate this by developing probiotic applications to target the problem of metritis in the dairy industry, and evaluate LAB synthesized glycans for their potential in preventing and treating post-weaning diarrhoea (PWD) in swine production.;Using culture-dependent analysis, PCR clone library construction, and quantitative PCR (qPCR), main bacterial species that constituted the microbiota of both healthy and infected bovine reproductive tracts were isolated and identified. Using selected LAB from healthy cows, freeze dried probiotics were prepared and used as intravaginal administrations for treating infected cows. Animal trial results obtained by Dr. Ametaj’s research group have indicated improvements in the reproductive performance of the treated cows.;In terms of evaluating LAB derived glycans for preventing and treating PWD in swine, the porcine erythrocyte haemagglutination model was used to test for anti-adhesion properties in LAB exopolysaccharides (EPS). Glycans including reuteran, glucan and levan that were produced by Lactobacillus reuteri were found to exhibit anti-adhesion properties. However, animal studies will need to be conducted to confirm potential in vivo effects. In order to produce novel and potentially anti-adhesive glycans that can prevent a wider range of pathogenic bacteria from adhering to their target hosts, alpha-galactosidases (α-Gal) from Lb. reuteri, which are capable of producing alpha-galacto-oligosaccharides (α-GOS) were cloned and characterized. Using different acceptor sugars, the production of a variety of α-GOS was detected by high performance liquid chromatography (HPLC) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). Both in vitro and in vivo anti-adhesion studies will be required to further studies the potential anti-adhesive properties of novel enzyme-synthesized α-GOS.;Results obtained from this thesis research will facilitate the development of versatile novel probiotics and therapeutic glycans for applications in food and feed products in order to enhance the health of farm animals and humans alike. |
