{"id":{"repo_id":"uwo","oai_identifier":"oai:uwo.scholaris.ca:20.500.14721/27003"},"canonical_url":"https://search.dev.ndltd.org/etd/uwo/oai:uwo.scholaris.ca:20.500.14721/27003","repository":{"repo_id":"uwo","name":"Western University","base_url":"https://uwo.scholaris.ca/server/oai/request"},"display":{"title":"Evaluating the Co-commensal Lifestyles of Staphylococcus aureus and Staphylococcus epidermidis","abstract":"Staphylococcus epidermidis is a ubiquitous skin commensal, and produces a serine protease Esp that can eradicate nasal carriage of the opportunistic pathogen, Staphylococcus aureus. We evaluated the ability of S. epidermidis and S. aureus to express serine protease and compete with one another in response to acidic pH and unsaturated free fatty acids; conditions encountered on human skin. The hypervirulent USA300 strain of S. aureus was more competitive in co-culture conditions of acidic pH or 25 µM palmitoleic acid alone, but could not compete with S. epidermidis when these conditions were combined. Conversely, in pure culture, these conditions promoted abundant expression of the SspA serine protease by S. aureus, but repressed expression of the orthologous Esp protease by S. epiderimidis. Thus, in response to conditions that would be encountered on skin, pathogenic S. aureus maintained production of secreted virulence factors, but S. epidermidis had a competitive growth advantage.","abstract_html":"Staphylococcus epidermidis is a ubiquitous skin commensal, and produces a serine protease Esp that can eradicate nasal carriage of the opportunistic pathogen, Staphylococcus aureus. We evaluated the ability of S. epidermidis and S. aureus to express serine protease and compete with one another in response to acidic pH and unsaturated free fatty acids; conditions encountered on human skin. The hypervirulent USA300 strain of S. aureus was more competitive in co-culture conditions of acidic pH or 25 µM palmitoleic acid alone, but could not compete with S. epidermidis when these conditions were combined. Conversely, in pure culture, these conditions promoted abundant expression of the SspA serine protease by S. aureus, but repressed expression of the orthologous Esp protease by S. epiderimidis. Thus, in response to conditions that would be encountered on skin, pathogenic S. aureus maintained production of secreted virulence factors, but S. epidermidis had a competitive growth advantage.","abstract_has_math":false,"creators":["Gnanasuntharam, Piraveina"],"institution":"The University of Western Ontario","degree_name":"M Sc","degree_level":null,"degree_discipline":"Microbiology and Immunology","degree_department":null,"school":null,"contributors":[],"advisors":["Martin McGavin"],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-08-26","date_published":"2013-08-26","updated_at":"2026-07-27T21:56:16Z","subjects":["S. epidermidis","USA300","unsaturated free fatty acid","acidic pH","SspA","Esp"],"languages":["en_ca"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/20.500.14721/27003","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Martin McGavin"]},{"key":"dc:creator","label":"Author","values":["Gnanasuntharam, Piraveina"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-07-10T15:16:26Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-07-10T15:16:26Z"]},{"key":"dc:date.issued","label":"Date","values":["2013-08-26"]},{"key":"dc:publisher","label":"Institution","values":["The University of Western Ontario"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Microbiology and Immunology"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M Sc"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["S. epidermidis","USA300","unsaturated free fatty acid","acidic pH","SspA","Esp"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_ca"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/20.500.14721/27003"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The thesis cover page in the PDF document includes references to Western University’s previous institutional repository platform, known as Scholarship@Western, and links to that platform (beginning with ir.lib.uwo.ca). In citing or referring to this thesis, use the DOI or handle from this page instead. Sample citation: Author name, \"Thesis title.\" (Year). Western University Open Repository. https://doi.org/10.71858/123456."]},{"key":"dc:description.abstract","label":"Abstract","values":["Staphylococcus epidermidis is a ubiquitous skin commensal, and produces a serine protease Esp that can eradicate nasal carriage of the opportunistic pathogen, Staphylococcus aureus. We evaluated the ability of S. epidermidis and S. aureus to express serine protease and compete with one another in response to acidic pH and unsaturated free fatty acids; conditions encountered on human skin. The hypervirulent USA300 strain of S. aureus was more competitive in co-culture conditions of acidic pH or 25 µM palmitoleic acid alone, but could not compete with S. epidermidis when these conditions were combined. Conversely, in pure culture, these conditions promoted abundant expression of the SspA serine protease by S. aureus, but repressed expression of the orthologous Esp protease by S. epiderimidis. Thus, in response to conditions that would be encountered on skin, pathogenic S. aureus maintained production of secreted virulence factors, but S. epidermidis had a competitive growth advantage."]},{"key":"dc:title","label":"Title","values":["Evaluating the Co-commensal Lifestyles of Staphylococcus aureus and Staphylococcus epidermidis"]}]}],"canonical_facts":{"dc:contributor.advisor":["Martin McGavin"],"dc:creator":["Gnanasuntharam, Piraveina"],"dc:date.accessioned":["2025-07-10T15:16:26Z"],"dc:date.available":["2025-07-10T15:16:26Z"],"dc:date.issued":["2013-08-26"],"dc:description":["The thesis cover page in the PDF document includes references to Western University’s previous institutional repository platform, known as Scholarship@Western, and links to that platform (beginning with ir.lib.uwo.ca). In citing or referring to this thesis, use the DOI or handle from this page instead. Sample citation: Author name, \"Thesis title.\" (Year). Western University Open Repository. https://doi.org/10.71858/123456."],"dc:description.abstract":["Staphylococcus epidermidis is a ubiquitous skin commensal, and produces a serine protease Esp that can eradicate nasal carriage of the opportunistic pathogen, Staphylococcus aureus. We evaluated the ability of S. epidermidis and S. aureus to express serine protease and compete with one another in response to acidic pH and unsaturated free fatty acids; conditions encountered on human skin. The hypervirulent USA300 strain of S. aureus was more competitive in co-culture conditions of acidic pH or 25 µM palmitoleic acid alone, but could not compete with S. epidermidis when these conditions were combined. Conversely, in pure culture, these conditions promoted abundant expression of the SspA serine protease by S. aureus, but repressed expression of the orthologous Esp protease by S. epiderimidis. Thus, in response to conditions that would be encountered on skin, pathogenic S. aureus maintained production of secreted virulence factors, but S. epidermidis had a competitive growth advantage."],"dc:identifier.uri":["https://hdl.handle.net/20.500.14721/27003"],"dc:language.iso":["en_ca"],"dc:publisher":["The University of Western Ontario"],"dc:subject":["S. epidermidis","USA300","unsaturated free fatty acid","acidic pH","SspA","Esp"],"dc:title":["Evaluating the Co-commensal Lifestyles of Staphylococcus aureus and Staphylococcus epidermidis"],"dc:type":["thesis"],"thesis:degree_discipline":["Microbiology and Immunology"],"thesis:degree_name":["M Sc"]},"updated_at":"2026-07-27T21:56:16Z"}