Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae

Detalhes bibliográficos
Autor(a) principal: Solanki, Konil Hasmuk
Data de Publicação: 2022
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
Texto Completo: http://hdl.handle.net/10451/57470
Resumo: Tese de mestrado, Microbiologia Aplicada, 2022, Universidade de Lisboa, Faculdade de Ciências
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spelling Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniaeStreptococcus oralisStreptococcus mitisStreptococcus pneumoniaebacteriocinasbacterial cytological profilingTeses de mestrado - 2023Departamento de Biologia VegetalTese de mestrado, Microbiologia Aplicada, 2022, Universidade de Lisboa, Faculdade de CiênciasThe microbiota of the upper respiratory tract (URT) plays an important role in protecting the host against respiratory pathogens. Most of the microbial communities in the URT are commensal bacteria. However, some of the colonizers are opportunistic pathogens such as Streptococcus pneumoniae. S. pneumoniae is a Gram-positive bacterium responsible for causing infections such as otitis media, sinusitis, meningitis, bacteremia and pneumonia. Such infections remain common among children, elders and immunocompromised patients despite the introduction of vaccines. Furthermore, the emergence of antibiotic resistance has narrowed the treatment options. Previously at the Molecular Microbiology of Human Pathogens Laboratory, seven strains were identified as commensal streptococci - Streptococcus oralis and Streptococcus mitis - which inhibited most strains of a diverse pneumococcal collection. The genomic analysis of these commensal strains identified multiple putative bacteriocin loci. In this work, the inhibitory potential of three bacteriocin loci (B2 from a S. oralis strain and B6 and C3 from a S. mitis strain) against the pneumococci was evaluated. Deletion mutants for each locus were constructed and cell-free supernatants were obtained and tested for inhibitory potential. A partial loss of inhibition was observed when the supernatants of the B2 and B6 loci deletion mutants were tested against pneumococci in well-diffusion assays and during planktonic growth. Bacterial cytological profiling was performed to obtain insights on the mechanism of action of the bacteriocins in the loci under study. Fluorescence microscopy imaging suggested an increased permeability in cells treated with the supernatant of the S. mitis wild-type strain which was not observed in cells treated with the supernatant of the corresponding B6 deletion mutant. In conclusion, in the conditions tested the bacteriocins from the B2 and B6 loci have a small effect on the inhibition of S. pneumoniae. The B6 locus possibly targets the pneumococcal cell membrane leading to its disruption.Leão, Raquel SáChambel, Lélia Mariana Marcão, 1964-Repositório da Universidade de LisboaSolanki, Konil Hasmuk202320222025-11-28T00:00:00Z2023-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10451/57470TID:203492803enginfo:eu-repo/semantics/embargoedAccessreponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiainstacron:RCAAP2025-03-17T14:57:12Zoai:repositorio.ulisboa.pt:10451/57470Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireinfo@rcaap.ptopendoar:https://opendoar.ac.uk/repository/71602025-05-29T03:30:06.712928Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiafalse
dc.title.none.fl_str_mv Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
title Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
spellingShingle Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
Solanki, Konil Hasmuk
Streptococcus oralis
Streptococcus mitis
Streptococcus pneumoniae
bacteriocinas
bacterial cytological profiling
Teses de mestrado - 2023
Departamento de Biologia Vegetal
title_short Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
title_full Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
title_fullStr Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
title_full_unstemmed Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
title_sort Characterization of commensal strains with bacteriocinmediated inhibition against Streptococcus pneumoniae
author Solanki, Konil Hasmuk
author_facet Solanki, Konil Hasmuk
author_role author
dc.contributor.none.fl_str_mv Leão, Raquel Sá
Chambel, Lélia Mariana Marcão, 1964-
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Solanki, Konil Hasmuk
dc.subject.por.fl_str_mv Streptococcus oralis
Streptococcus mitis
Streptococcus pneumoniae
bacteriocinas
bacterial cytological profiling
Teses de mestrado - 2023
Departamento de Biologia Vegetal
topic Streptococcus oralis
Streptococcus mitis
Streptococcus pneumoniae
bacteriocinas
bacterial cytological profiling
Teses de mestrado - 2023
Departamento de Biologia Vegetal
description Tese de mestrado, Microbiologia Aplicada, 2022, Universidade de Lisboa, Faculdade de Ciências
publishDate 2022
dc.date.none.fl_str_mv 2022
2023
2023-01-01T00:00:00Z
2025-11-28T00:00:00Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/57470
TID:203492803
url http://hdl.handle.net/10451/57470
identifier_str_mv TID:203492803
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/embargoedAccess
eu_rights_str_mv embargoedAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron:RCAAP
instname_str FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron_str RCAAP
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reponame_str Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
collection Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
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repository.mail.fl_str_mv info@rcaap.pt
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