Adaptation of Salmonella enterica Hadar under static magnetic field: effects on outer membrane protein pattern

Abstract

BackgroundSalmonella enterica serovar Hadar (S. Hadar) is a highly prevalent foodborne pathogen and therefore a major cause of human gastroenteritis worldwide. Outer membrane proteins whose production is often regulated by environmental conditions also play important roles in the adaptability of bacterial pathogens to various environments.ResultsThe present study investigated the adaptation of S. Hadar under the effect of acute static magnetic field exposure (200 mT, 9 h) and the impact on the outer membrane protein pattern. Via two-dimensional electrophoresis (2-DE) and LC-MS/MS spectrometry, we compared the proteome of enriched-outer membrane fraction before and after exposure to a magnetic field. A total of 11 proteins, displaying more than a two-fold change, were differentially expressed in exposed cells, among which 7 were up-regulated and 4 down-regulated. These proteins were involved in the integrity of cell envelope (TolB, Pal), in the response to oxidative stress (OmpW, dihydrolipoamide dehydrogenase, UspF), in the oxidative stress status (bacterioferritin), in virulence (OmpX, Yfgl) or in motility (FlgE and UspF). Complementary experiments associated the down-regulation of FlgE and UspF with an alteration of swarming, a flagella-driven motility, under SMF. Furthermore, the antibiotic disc diffusion method confirmed a decrease of gentamicin susceptibility in exposed cells. This decrease could be partly associated with the up-regulation of TolC, outer membrane component of an efflux pump. OmpA, a multifunctional protein, was up-regulated.ConclusionsSMF (200 mT) seems to maintain the cell envelope integrity and to submit the exposed cells to an oxidative stress. Some alterations suggest an increase of the ability of exposed cells to form biofilms.

A Critical Role of Bacterioferritin in Salmonella pullorum-Induced IFN-β Expression in DF-1 Cells

“…Bfr, a 17-kDa protein that was previously identified as an outer membrane protein of S. hadar , is composed of 24 identical subunits along with the usual ferroxidase sites that have 12 binding sites for heme iron ( Wong et al, 2009 ; Snoussi et al, 2012 ). Bfr is also the major Fe storage protein in Salmonella ( Velayudhan et al, 2007 ).…”

“…The iron that is acquired by the pathogenic bacterium is used for numerous biochemical activities and any surplus iron that is available is stored within the bacterial cell in the form of Bfr ( Ratledge, 2007 ). Bfr belongs to an outer membrane protein in S. hadar as examined by a proteomic approach ( Snoussi et al, 2012 ). Bfr is a major iron storage protein and protects against hydrogen peroxide toxicity, and the haeme-containing Bfr was found exclusively in bacteria ( Velayudhan et al, 2007 ).…”

Identification of Salmonella enterica Serovar Typhimurium Genes Regulated during Biofilm Formation on Cholesterol Gallstone Surfaces

“…Thus, considering the effect of the ycfR mutation in E. coli (induction of acid, osmotic, oxidative, and heat stress response genes), we believe that during biofilm formation on cholesterol gallstones, ycfR is induced as a response to the stress generated during biofilm formation on cholesterol due to bacterial-membrane damage that has been reported to occur (86,87). The stress response during biofilm formation is a well-reported phenomenon in E. coli and Salmonella (88)(89)(90).…”

Effect of Temperature and Gamma Radiation on Salmonella Hadar Biofilm Production on Different Food Contact Surfaces

“…We have previously described the effects of stress conditions (gamma radiation and static magnetic field) on S. Hadar. [13,15]. In this work, we investigated the effect of ionizing radiation (gamma rays), temperature, materials, and the expression of agfD and adrA genes on Salmonella Hadar biofilm formation.…”