Person:
Domenech Lucas, Miriam

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First Name
Miriam
Last Name
Domenech Lucas
URI
https://hdl.handle.net/20.500.14352/80736
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Biológicas
Department
Genética, Fisiología y Microbiología
Area
Microbiología
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Author: Ernesto García × End date: 2009 ×

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    Versatility of the capsular genes during biofilm formation by Streptococcus pneumoniae
    (Environmental Microbiology, 2009) Domenech Lucas, Miriam; Ernesto García; Miriam Moscoso
    Streptococcus pneumoniae forms part of the natural microbiota of the nasopharynx. For the pneumococcus to cause infection, colonization needs to occur and this process is mediated by adherence of bacteria to the respiratory epithelium. Although the capsular polysaccharide (CPS) of S. pneumoniae is known to be important for infection to occur, its role in colonization is controversial. Biofilm models are starting to emerge as a promising tool to investigate the role of CPS during nasopharyngeal carriage, which is the first step in the dissemination and initiation of a pneumococcal infection. Using a well-defined model system to analyse in vitro biofilm formation in pneumococcus, here we explore the molecular changes underlying the appearance of capsular mutants using type 3 S. pneumoniae cells. Spontaneous colony phase variants show promoter mutations, as well as duplications, deletions and point mutations in the cap3A gene, which codes for a UDP-glucose dehydrogenase (UDP-GlcDH). Increased biofilm-forming capacity could usually be correlated with a reduction both in colony size and in the relative amount of CPS present on the cell surface of each colony variant. However, a mutation in Cap3A Thr83Ile (a strictly conserved residue in bacterial UDP-GlcDHs) that resulted in very low CPS production also led to impaired biofilm formation. We propose that non-encapsulated mutants of pneumococcal type 3 strains are essentially involved in the initial stages (the attachment stage) of biofilm formation during colonization/pathogenesis.