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Athabasca University

Shawn Lewenza, PhD

Associate Professor
Environmental Health,
Faculty of Science and Technology



My undergraduate BSc and graduate PhD degrees were completed in Microbiology, with a specialization in studying bacterial pathogens and how they cause disease. I did postdoctoral fellowships at the University of British Columbia, and the Institut Pasteur in Paris, France. Most of my research to date has been focussed on studying how bacteria that are ubiquitous in the environment also cause disease in individuals that are immunocompromised. The problems of interest are the mechanisms of antibiotic resistance, immune evasion and how biofilms promote long-term survival.

I am a member of the Athabasca River Basin Research Institute (ARBRI) and also an Adjunct Associate Professor at the University of Calgary, in the Department of Microbiology, Immunology and Infectious Diseases.


We are now into a genomic era where countless bacterial genome sequences are available due to breakthroughs in rapid and low cost DNA sequencing technology. Genomic methods are therefore needed to understand the systems biology of any single organism, or to compare the genomes of different organisms. New technologies in DNA synthesis and sequencing are accelerating the pace of discovery and in creating new biotechnologies. Examples include the use of microbes to produce biofuels, using sunlight or wood waste as an energy source, or the production of pharmaceuticals in yeast.

My current research interest is to design bacterial technologies for use in detecting toxins in industrial or municipal waste water. Using genomic and metagenomic methods, we are also interested in studying the bacterial communities in the oil sands process-affected water (OSPW) to understand the natural bioremediation capacity of organisms growing in this toxic environment. The goal of this research is to build new technologies to improve environmental monitoring of water, and to ultimately improve bioremediation and treatment of organic toxins in the tailings ponds, the water from which will ultimately be returned to the Athabasca River.


Synthetic biology employs genetic engineering to microbes with the goal of producing new technologies that have great potential to transform our health and the environment. Visit my blog to learn more about these new technologies and ideas.


DNA is an antimicrobial component of neutrophil extracellular traps. Halverson TW, Wilton M, Poon KK, Petri B, Lewenza S. PLoS Pathog. 2015 Jan 15;11(1):e1004593. doi: 10.1371/journal.ppat.1004593. eCollection 2015 Jan.

Feeding behaviour of Caenorhabditis elegans is an indicator of Pseudomonas aeruginosa PAO1 virulence. Lewenza S, Charron-Mazenod L, Giroux L, Zamponi AD. PeerJ. 2014 Aug 12;2:e521. doi: 10.7717/peerj.521. eCollection 2014.

Extracellular DNA-induced antimicrobial peptide resistance in Salmonella enterica serovar Typhimurium. Johnson L, Horsman SR, Charron-Mazenod L, Turnbull AL, Mulcahy H, Surette MG, Lewenza S. BMC Microbiol. 2013 May 24;13(1):115. [Epub ahead of print]

Extracellular DNA-induced antimicrobial peptide resistance mechanisms in Pseudomonas aeruginosa. Lewenza S. Front Microbiol. 2013;4:21. doi: 10.3389/fmicb.2013.00021.

Calcium chelation by alginate activates the type III secretion system in mucoid Pseudomonas aeruginosa biofilms. Horsman SR, Moore RA, Lewenza S. PLoS One. 2012;7(10):e46826. doi: 10.1371/journal.pone.0046826. Epub 2012 Oct 8.

Inhibition of bacterial biofilm formation and swarming motility by a small synthetic cationic peptide. de la Fuente-Núñez C, Korolik V, Bains M, Nguyen U, Breidenstein EB, Horsman S, Lewenza S, Burrows L, Hancock RE. Antimicrob Agents Chemother. 2012 May;56(5):2696-704. doi: 10.1128/AAC.00064-12. Epub 2012 Feb 21.

Surface-localized spermidine protects the Pseudomonas aeruginosa outer membrane from antibiotic treatment and oxidative stress. Johnson L, Mulcahy H, Kanevets U, Shi Y, Lewenza S. J Bacteriol. 2011 Dec 9. [Epub ahead of print]

Drosophila melanogaster as an Animal Model for the Study of Pseudomonas aeruginosa Biofilm Infections In Vivo. Mulcahy H, Sibley CD, Surette MG, Lewenza S. PLoS Pathog. 2011 Oct;7(10):e1002299. Epub 2011 Oct 6.

Magnesium Limitation Is an Environmental Trigger of the Pseudomonas aeruginosa Biofilm Lifestyle. Mulcahy H, Lewenza S.PLoS One. 2011;6(8):e23307. Epub 2011 Aug 16.

Identification of bacterial contaminants in sinus irrigation bottles from chronic rhinosinusitis patients. Lewenza S, Charron-Mazenod L, Cho JJ, Mechor B. J Otolaryngol Head Neck Surg. 2010 Aug;39(4):458-63.

Pseudomonas aeruginosa produces an extracellular deoxyribonuclease that is required for utilization of DNA as a nutrient source. Mulcahy H, Charron-Mazenod L, Lewenza S. Environ Microbiol. 2010 Jun;12(6):1621-9. Epub 2010 Mar 29.

Extracellular DNA chelates cations and induces antibiotic resistance in Pseudomonas aeruginosa biofilms. Mulcahy H, Charron-Mazenod L, Lewenza S. PLoS Pathog. 2008 Nov;4(11):e1000213. Epub 2008 Nov 21.

Novel inner membrane retention signals in Pseudomonas aeruginosa lipoproteins. Lewenza S, Mhlanga MM, Pugsley AP.J Bacteriol. 2008 Sep;190(18):6119-25. Epub 2008 Jul 18.

Identification of genes involved in swarming motility using a Pseudomonas aeruginosa PAO1 mini-Tn5-lux mutant library. Overhage J, Lewenza S, Marr AK, Hancock RE. J Bacteriol. 2007 Mar;189(5):2164-9. Epub 2006 Dec 8.

Contribution of the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems to Mg2+-induced gene regulation in Pseudomonas aeruginosa. McPhee JB, Bains M, Winsor G, Lewenza S, Kwasnicka A, Brazas MD, Brinkman FS, Hancock RE.    J Bacteriol. 2006 Jun;188(11):3995-4006.

Direct visualization of red fluorescent lipoproteins indicates conservation of the membrane sorting rules in the family Enterobacteriaceae. Lewenza S, Vidal-Ingigliardi D, Pugsley AP. J Bacteriol. 2006 May;188(10):3516-24.

Construction of a mini-Tn5-luxCDABE mutant library in Pseudomonas aeruginosa PAO1: a tool for identifying differentially regulated genes. Lewenza S, Falsafi RK, Winsor G, Gooderham WJ, McPhee JB, Brinkman FS, Hancock RE. Genome Res. 2005 Apr;15(4):583-9.

Genome-wide identification of Pseudomonas aeruginosa exported proteins using a consensus computational strategy combined with a laboratory-based PhoA fusion screen. Lewenza S, Gardy JL, Brinkman FS, Hancock RE. Genome Res. 2005 Feb;15(2):321-9.

Cationic antimicrobial peptides activate a two-component regulatory system, PmrA-PmrB, that regulates resistance to polymyxin B and cationic antimicrobial peptides in Pseudomonas aeruginosa. McPhee JB, Lewenza S, Hancock RE. Mol Microbiol. 2003 Oct;50(1):205-17.

Interspecies communication between Burkholderia cepacia and Pseudomonas aeruginosa. Lewenza S, Visser MB, Sokol PA.Can J Microbiol. 2002 Aug;48(8):707-16.

Updated September 16 2015 by Student & Academic Services

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