Characterization of Disinfectant and Phage Resistance Determinants of Listeria monocytogenes
Year: 2011
Type: article
Abstract: DUTTA, VIKRANT.Characterization of Disinfectant and Phage Resistance Determinants of Listeria monocytogenes.(Under the direction of Dr. Sophia Kathariou).Environmental contamination of food plays a key role in transmission of Listeria monocytogenes.Adaptations such as ability to grow under refrigeration, biofilm formation, disinfectant resistance, and resistance to phage are crucial to the survival of L. monocytogenes in the environment.Here we have investigated some of the adaptations that may contribute towards environmental persistence of this pathogen.These include disinfectant (quaternary ammonium compounds, QAC) resistance, temperature-dependent resistance to phage among epidemic clone II strains, triphenylmethane dye reduction and resistance to heavy metals such as cadmium.Using in silico analysis, we have analyzed the prevalence of cadAC efflux systems associated with cadmium resistance among different Listeria genomes.Of the three distinct cadAC types known to date in L. monocytogenes, two (cadA1C1 and cadA2C2) were harbored by plasmids and were encountered in diverse strains of L. monocytogenes and (in the case of cadA2C2) non-pathogenic Listeria spp.Large plasmids from two different epidemicassociated strains of L. monocytogenes harbored cadA2C2 together with a drug efflux system (bcrABC), and both determinants were associated with a putative IS1216 transposon.Plasmid-cured derivatives of these strains were susceptible both to cadmium and to BC. Genetic analyses revealed that cadA2C2 was sufficient for restoring resistance to cadmium to a plasmid-cured derivative of L. monocytogenes H7550.Furthermore, bcrABC was sufficient for restoring resistance to high levels of QAC to the plasmid-cured strain.The transcription of bcrABC was temperature-dependent, with higher transcript levels at 37°C than at 25°C or below.The bcrABC system was encountered among L. monocytogenes DEDICATION I would like to dedicate this dissertation to my grandmother Tara Devi Dutta whose unconditional love, values, and vision have been and will be a sole source of inspiration throughout my life.
Author: Vikrant Dutta
Language: English
Subfield: Biotechnology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W72664489