Impact of host gut microbiome on pathogen colonization

• Main Author: Low, Wai Leong
• Other Authors: Yang Liang
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Biological sciences::Microbiology::Bacteria
• Online Access: http://hdl.handle.net/10356/63612
• Institution: Nanyang Technological University

The human gastrointestinal tract is colonized by at least 400 different microbial species, known as the gut microbiota, which play vital roles in our health. Most importantly, they are able to confer protection against intestinal diseases by limiting the colonization of exogenous pathogens in the gut. Compositional changes in this commensal gut microbiota result in the outgrowth of gut pathogens, but the mechanisms underlying this phenomenon remain largely unexplored. Hence, it would benefit the field of medical microbiology to understand the roles played by the gut microbiota in resisting the colonization of gut pathogens. In this study, we investigated the molecular mechanisms of opportunistic pathogen Pseudomonas aeruginosa, during its colonization in the mouse gut model. We demonstrated that the production of intracellular bis-(3’- 5’)-cyclic dimeric guanosine monophosphate is important for stable colonization of P. aeruginosa in the mouse gut. Unexpectedly, we also discovered that the bile salts which are normally present in the gut could promote P. aeruginosa gut colonization possibly by repressing swarming motility, enhancing surface adhesion and stimulating biofilm formation. Finally, we postulated that these colonization-promoting factors are being down-regulated by the commensal gut microbiota in the effort to resist the gut colonization by P. aeruginosa.