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Title: Effect of the environment on gene transfer in Clostridium difficile
Author: Khodadoost, Ladan
ISNI:       0000 0004 8507 6476
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Clostridium difficile is a pathogenic bacterium that can colonise both humans and various animals. Toxin production leads to clinical symptoms ranging from mild to severe diarrhoea and can result in potentially fatal pseudomembranous colitis. These symptoms are caused by the disruption of the cytoskeleton and tight junctions of gut epithelial cells by the toxins. C. difficile responds to several biological compounds found in the human intestinal environment such as bile salts leading to spore germination and colonization. In this study we investigated the response of C. difficile to mammalian pancreatic α-amylase with production of a mucoid colony phenotype that results from increased secretion of extracellular proteins and carbohydrates. Furthermore, the effect of amylase on horizontal gene transfer in C. difficile was investigated using conjugative transposon Tn5397 and non-conjugative mobilisable plasmid pMTL9301. A significant increase in the frequency of Tn5397 transfer was observed when amylase was present. pMTL9301 transfer was not affected by amylase but significantly decreased when DNase was added to eliminate transformation. Further investigations into the molecular basis of the DNase-sensitive plasmid transfer into C. difficile showed that the oriT region of pMTL9301 (derived from RK2) is not required for transfer between E. coli and C. difficile strains 630Δerm and CD37 and that this oriT-independent transfer is abolished in the presence of DNase when CD37 is the recipient. Transfer to the 630Δerm strain is DNase resistant even without an obvious oriT, when E. coli CA434 is used as a donor and is sensitive to DNase when E. coli HB101 is the donor, suggesting that a 'novel cell-to-cell transformation-like mechanism' occurs in C. difficile.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available