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Title: Quorum sensing signals in biofilms : understanding the impact of AI-2 on the molecular mechanisms in Bacillus cereus biofilms
Author: Karunakaran, Esther
ISNI:       0000 0004 2742 4647
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2012
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In nature, bacteria can exist as a multi species consortium of cells adherent to a surface and able to co-ordinate cellular metabolism via quorum sensing molecules. The effect of biofilm formation can have both positive as well as negative impacts on human society. In order to engineer systems where the positive impacts of biofilms are enhanced and the negative impacts are curbed, a detailed understanding of the environmental signals and molecular mechanisms that trigger the formation and maintenance of biofilms is necessary. As a first step in this direction, the molecular mechanisms underlying the formation of biofilms arc investigated in Bacillus cereus; biofi Im formation in which has positive impacts on society such as. aiding waste water treatment and bioremediation as well as negative impacts such as biofouling of implants and causation of disease. This investigation of cell surface characteristics and production of extracellular polymeric substances via Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zetapotcntial analysis and various techniques in proteomics suggest that during biofilm formation, the surface chemistry of the cells and the composition of the EPS changes, most likely by glyeosylation of surface and secreted polymers, in order to aid biofilm formation and that biofilms arc predominantly stabilized by electrostatic interactions between the cell surface and EPS polymers. This work also establishes that the presence of other microorganisms in the culture environment, mimicked by the addition of quorum sensing signal, Al-2 affects the surface chemistry, motility, cellular metabolism and EPS production in Bacillus cereus and improves biofilm formation in Bacillus cereus. The use of quorum sensing signals could therefore be a possible mechanism for biofilm control. However, additional investigations into the glycobiome of Bacillus cereus and the regulation of post translation control need to be carried out before quorum sensing signals can be employed to reliably control biofilm formation in Bacillus cereus.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available