Year: 2015
Type: dissertation
Abstract: Bacteria are often thought as single cell organisms, however they can develop into morphologically complex multicellular communities composed of different subpopulations of specialized cell types. Biofilm is an example, in which bacteria organize for protection from harmful conditions in the host and to create nutrient-rich areas. In the last years biofilm have been show to comprise an important aspect of microbial persistence in the human gut. Endospore-formers, although thought not to be major constituents of the microbiota in the human intestine, cause several intestinal diseases, usually associated with antibiotic use. Whether these bacteria persist in the intestine in biofilms or as endospores is not totally elucidated since both, biofilms and endospores, are able to resist to antimicrobial agents. Most likely sporulation and biofilm formation are tightly linked processes. For some endosporeformers, spore differentiation is induced by a sub-population of cells within the biofilm. In this work we tackled the link between bacterial biofilms and endosporulation in Bacillus subtilis. We showed that endospores produced in biofilms have higher resistance to UV radiation. We revealed that a gene, remA, conserved among endosporeformers and essential for biofilm formation is expressed during sporulation. remA is expressed in the forespore soon after asymmetric division and in the mother cell after engulfment completion. GerE represses remA expression in the mother cell at late stages of sporulation. Consequently, we found components of the biofilm matrix, TasA and BslA, on the coat of endospores produced in biofilms. We suggest that components of the biofilm matrix may be part of mature endospores. We hypothesize that some of the structural proteins that confer integrity to the matrix biofilm, as TasA, may have a role as a scaffold for the assembly of the endospore surface layers.
Author: Inês Cunha Portinha
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Funder: Universidade de Lisboa
OpenAlex ID: W2797467043