The Impact of Nickel on Lux I/LuxR-Type Quorum Sensing and Biofilm Formation of Environmental Proteobacterial Species
Alvarez, Pedro J.
Doctor of Philosophy
The ability to control the establishment and development of a biofilm is important in environmental engineering where biofilms are used to recycle wastes and remove toxins from the environment, or conversely, reduce the life of infrastructure due to corrosion. This thesis reports on the metal nickel and its influence on biofilm formation. Using a combination of bench top and molecular methods, I demonstrate that nickel ions decrease the expression of N-acyl homoserine lactone synthase and transcriptional activator genes and subsequently, biofilm formation in Burkholderia multivorans ATCC 17616 without affecting overall viability. I further demonstrate that this phenomenon is not limited to nickel and/or B. multivorans. I have identified an additional heavy metal, cadmium that down regulates the expression of homoserine lactone genes and subsequently decreases surface colonization. Traits such as twitching motility, elastase and pyocyanin production, which are influenced by quorum sensing mechanisms in Burkholderia and Pseudomonas, are also inhibited by nickel and cadmium ions.
Biofilm; Quorum sensing; N-acyl homoserine lactone; Nickel; Cadmium