Contributions of Francisella tularensis subsp. novicida chitinases and Sec secretion system to biofilm formation on chitin.

TitleContributions of Francisella tularensis subsp. novicida chitinases and Sec secretion system to biofilm formation on chitin.
Publication TypeJournal Article
Year of Publication2010
AuthorsMargolis, JJ, El-Etr S, Joubert L-M, Moore E, Robison R, Rasley A, Spormann AM, Monack DM
JournalApplied and environmental microbiology
Date Published2010 Jan
KeywordsAcetylglucosamine, Animals, Bacterial Proteins, Biofilms, Cells, Cultured, Chitin, Chitinase, Female, Francisella tularensis, Mice, Mice, Inbred C57BL
AbstractFrancisella tularensis, the zoonotic cause of tularemia, can infect numerous mammals and other eukaryotes. Although studying F. tularensis pathogenesis is essential to comprehending disease, mammalian infection is just one step in the ecology of Francisella species. F. tularensis has been isolated from aquatic environments and arthropod vectors, environments in which chitin could serve as a potential carbon source and as a surface for attachment and growth. We show that F. tularensis subsp. novicida forms biofilms during the colonization of chitin surfaces. The ability of F. tularensis to persist using chitin as a sole carbon source is dependent on chitinases, since mutants lacking chiA or chiB are attenuated for chitin colonization and biofilm formation in the absence of exogenous sugar. A genetic screen for biofilm mutants identified the Sec translocon export pathway and 14 secreted proteins. We show that these genes are important for initial attachment during biofilm formation. We generated defined deletion mutants by targeting two chaperone genes (secB1 and secB2) involved in Sec-dependent secretion and four genes that encode putative secreted proteins. All of the mutants were deficient in attachment to polystyrene and chitin surfaces and for biofilm formation compared to wild-type F. novicida. In contrast, mutations in the Sec translocon and secreted factors did not affect virulence. Our data suggest that biofilm formation by F. tularensis promotes persistence on chitin surfaces. Further study of the interaction of F. tularensis with the chitin microenvironment may provide insight into the environmental survival and transmission mechanisms of this pathogen.
Alternate JournalAppl. Environ. Microbiol.
0 November 24, 2010