Different assembly of acid and salt tolerance response in two dairy Listeria monocytogenes wild strains
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ORIGINAL PAPER
Different assembly of acid and salt tolerance response in two dairy Listeria monocytogenes wild strains Jessie Melo • Peter William Andrew Maria Leonor Faleiro
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Received: 2 December 2012 / Revised: 11 February 2013 / Accepted: 14 February 2013 / Published online: 2 March 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract A lack on the association between acid tolerance response (ATR) and osmotolerance response (OTR) among Listeria monocytogenes dairy isolates was found. In order to evaluate how wild L. monocytogenes isolates mount tolerance responses under a sub-lethal pH and a low sodium chloride concentration (pH 5.5 and 3.5 % [w/v] NaCl), a proteomic approach was used. The ATR and OTR of two L. monocytogenes cheese dairy isolates (strain T8, serotype 4b and A9, serotype 1/2b or 3b) were determined. The proteomes of the adapted and non-adapted cultures were evaluated by 2-DE. One strain displayed an ATR, but not an OTR and the other displayed an OTR, but not an ATR. The ATR positive strain showed the over-production of proteins related with protein synthesis, protein folding, attainment of reduction power, ribose production and cell wall. In contrast, in the OTR-positive-strain proteins related with glycolysis, general stress and detoxification were identified. Keywords Listeria monocytogenes Stress response Acid adaptation Salt adaptation Proteome
Communicated by Wofgang Buckel. J. Melo M. L. Faleiro (&) Faculdade de Cieˆncias e de Tecnologia (FCT), Centro de Biomedicina Molecular e Estrutural (IBB), Universidade do Algarve, IBB-CBME, Campus de Gambelas, 8000-117 Faro, Portugal e-mail: [email protected] P. W. Andrew Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, UK
Introduction Listeria monocytogenes is a food-borne human pathogen, responsible for listeriosis, a severe invasive infection with a high mortality rate (Swaminathan and Gerner-Smidt 2007). This pathogen can survive under a wide-range of environmental stress conditions encountered both in foods, food-processing environments and inside the host (Gahan and Hill 1999). While L. monocytogenes has been isolated from a variety of food sources (Kathariou 2002), listeriosis outbreaks have been strongly associated with the consumption of dairy products, in particular cheese (Rudolf and Siegfried 2001; Swaminathan and Gerner-Smidt 2007). During cheese manufacturing processes, L. monocytogenes is exposed to a sub-lethal low pH environment and salt content that may induce tolerance responses (Faleiro et al. 2003). The exposure to moderate acid and salt stress can trigger physiological and genetic changes which allow the bacteria to survive lethal stress conditions (Cataldo et al. 2006). The ability of this pathogen to overcome stressful conditions is of particular interest in food safety, as the exposure to hostile environments frequently provides cross-protection against additional stresses, which the pathogen can encounter during the colonization of the host (Hill et al. 2002; Garn
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