scholarly journals Listeria monocytogenes Shows Temperature-Dependent and -Independent Responses to Salt Stress, Including Responses That Induce Cross-Protection against Other Stresses

2012 ◽  
Vol 78 (8) ◽  
pp. 2602-2612 ◽  
Author(s):  
Teresa M. Bergholz ◽  
Barbara Bowen ◽  
Martin Wiedmann ◽  
Kathryn J. Boor
Keyword(s):  
Salt Stress ◽  
Listeria Monocytogenes ◽  
Osmotic Stress ◽  
Parent Strain ◽  
Cross Protection ◽  
Temperature Dependent ◽  
Short Term ◽  
Transcript Levels ◽  
Content Type ◽  
Short Term Adaptation

ABSTRACTThe food-borne pathogenListeria monocytogenesexperiences osmotic stress in many habitats, including foods and the gastrointestinal tract of the host. During transmission,L. monocytogenesis likely to experience osmotic stress at different temperatures and may adapt to osmotic stress in a temperature-dependent manner. To understand the impact of temperature on the responses this pathogen uses to adapt to osmotic stress, we assessed genome-wide changes in theL. monocytogenesH7858 transcriptome during short-term and long-term adaptation to salt stress at 7°C and 37°C. At both temperatures, the short-term response to salt stress included increased transcript levels ofsigBand SigB-regulated genes, as well asmrpABCDEFG, encoding a sodium/proton antiporter. This antiporter was found to play a role in adaptation to salt stress at both temperatures; ΔmrpABCDEFGhad a significantly longer lag phase than the parent strain in BHI plus 6% NaCl at 7°C and 37°C. The short-term adaptation to salt stress at 7°C included increased transcript levels of two genes encoding carboxypeptidases that modify peptidoglycan. These carboxypeptidases play a role in the short-term adaptation to salt stress only at 7°C, where the deletion mutants had significantly different lag phases than the parent strain. Changes in the transcriptome at both temperatures suggested that exposure to salt stress could provide cross-protection to other stresses, including peroxide stress. Short-term exposure to salt stress significantly increased H2O2resistance at both temperatures. These results provide information for the development of knowledge-based intervention methods against this pathogen, as well as provide insight into potential mechanisms of cross-protection.

Imperfect crowding adaptation of mammalian cells towards osmotic stress and its modulation by osmolytes

2017 ◽  
Vol 13 (11) ◽  
pp. 2218-2221 ◽  
Author(s):  
David Gnutt ◽  
Oliver Brylski ◽  
Eugen Edengeiser ◽  
Martina Havenith ◽  
Simon Ebbinghaus
Keyword(s):  
Osmotic Stress ◽  
Mammalian Cells ◽  
Short Term ◽  
Short Term Adaptation

The short-term adaptation of cellular crowding after osmotic stress is imperfect but can be modulated by the osmolyte TMAO.

scholarly journals Mutant and Recombinant Phages Selected from In Vitro Coevolution Conditions Overcome Phage-Resistant Listeria monocytogenes

2020 ◽  
Vol 86 (22) ◽  
Author(s):  
Tracey Lee Peters ◽  
Yaxiong Song ◽  
Daniel W. Bryan ◽  
Lauren K. Hudson ◽  
Thomas G. Denes
Keyword(s):  
Listeria Monocytogenes ◽  
Host Range ◽  
Foodborne Pathogen ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Short Term ◽  
Content Type ◽  
Life Threatening ◽  
The Impact

ABSTRACT Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes. Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a two-phage cocktail on the regrowth of phage-resistant L. monocytogenes and the adaptation of the phages to overcome this resistance. We used whole-genome sequencing to identify mutations in the target host that confer phage resistance and in the phages that alter host range. We found that infections with Listeria phages LP-048, LP-125, or a combination of both select for different populations of phage-resistant L. monocytogenes bacteria with different regrowth times. Phages isolated from the end of the coevolution experiments were found to have gained the ability to infect phage-resistant mutants of L. monocytogenes and L. monocytogenes strains previously found to be broadly resistant to phage infection. Phages isolated from coinfected cultures were identified as recombinants of LP-048 and LP-125. Interestingly, recombination events occurred twice independently in a locus encoding two proteins putatively involved in DNA binding. We show that short-term coevolution of phages and their hosts can be utilized to obtain mutant and recombinant phages with adapted host ranges. These laboratory-evolved phages may be useful for limiting the emergence of phage resistance and for targeting strains that show general resistance to wild-type (WT) phages. IMPORTANCE Listeria monocytogenes is a life-threatening bacterial foodborne pathogen that can persist in food processing facilities for years. Phages can be used to control L. monocytogenes in food production, but phage-resistant bacterial subpopulations can regrow in phage-treated environments. Coevolution experiments were conducted on a Listeria phage-host system to provide insight into the genetic variation that emerges in both the phage and bacterial host under reciprocal selective pressure. As expected, mutations were identified in both phage and host, but additionally, recombination events were shown to have repeatedly occurred between closely related phages that coinfected L. monocytogenes. This study demonstrates that in vitro evolution of phages can be utilized to expand the host range and improve the long-term efficacy of phage-based control of L. monocytogenes. This approach may also be applied to other phage-host systems for applications in biocontrol, detection, and phage therapy.

scholarly journals Nisin Resistance of Listeria monocytogenes Is Increased by Exposure to Salt Stress and Is Mediated via LiaR

2013 ◽  
Vol 79 (18) ◽  
pp. 5682-5688 ◽  
Author(s):  
Teresa M. Bergholz ◽  
Silin Tang ◽  
Martin Wiedmann ◽  
Kathryn J. Boor
Keyword(s):  
Salt Stress ◽  
Listeria Monocytogenes ◽  
Safety Concern ◽  
Response Regulator ◽  
Brain Heart Infusion ◽  
Control Measures ◽  
Protective Effects ◽  
Wild Type ◽  
Content Type ◽  
Type Strains

ABSTRACTGrowth ofListeria monocytogeneson refrigerated, ready-to-eat food is a significant food safety concern. Natural antimicrobials, such as nisin, can be used to control this pathogen on food, but little is known about how other food-related stresses may impact how the pathogen responds to these compounds. Prior work demonstrated that exposure ofL. monocytogenesto salt stress at 7°C led to increased expression of genes involved in nisin resistance, including the response regulatorliaR. We hypothesized that exposure to salt stress would increase subsequent resistance to nisin and that LiaR would contribute to increased nisin resistance. Isogenic deletion mutations inliaRwere constructed in 7 strains ofL. monocytogenes, and strains were exposed to 6% NaCl in brain heart infusion broth and then tested for resistance to nisin (2 mg/ml Nisaplin) at 7°C. For the wild-type strains, exposure to salt significantly increased subsequent nisin resistance (P< 0.0001) over innate levels of resistance. Compared to the salt-induced nisin resistance of wild-type strains, ΔliaRstrains were significantly more sensitive to nisin (P< 0.001), indicating that induction of LiaFSR led to cross-protection ofL. monocytogenesagainst subsequent inactivation by nisin. Transcript levels of LiaR-regulated genes were induced by salt stress, and lmo1746 andtelAwere found to contribute to LiaR-mediated salt-induced nisin resistance. These data suggest that environmental stresses similar to those on foods can influence the resistance ofL. monocytogenesto antimicrobials such as nisin, and potential cross-protective effects should be considered when selecting and applying control measures for this pathogen on ready-to-eat foods.

scholarly journals Role of ctc from Listeria monocytogenes in Osmotolerance

2003 ◽  
Vol 69 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Rozenn Gardan ◽  
Ophélie Duché ◽  
Sabine Leroy-Sétrin ◽  
Jean Labadie
Keyword(s):  
Salt Stress ◽  
Heat Stress ◽  
Listeria Monocytogenes ◽  
Osmotic Stress ◽  
Minimal Medium ◽  
Stress Protein ◽  
Transcriptional Level ◽  
Osmotic Stress Tolerance ◽  
Electron Microscopy Analysis

ABSTRACT Listeria monocytogenes is a food-borne pathogen with the ability to grow under conditions of high osmolarity. In a previous study, we reported the identification of 12 proteins showing high induction after salt stress. One of these proteins is highly similar to the general stress protein Ctc of Bacillus subtilis. In this study, induction of Ctc after salt stress was confirmed at the transcriptional level by using RNA slot blot experiments. To explore the role of the ctc gene product in resistance to stresses, we constructed a ctc insertional mutant. No difference in growth was observed between the wild-type strain LO28 and the ctc mutant either in rich medium after osmotic or heat stress or in minimal medium after heat stress. However, in minimal medium after osmotic stress, the growth rate of the mutant was increased by a factor of 2. Moreover, electron microscopy analysis showed impaired morphology of the mutant grown under osmotic stress conditions in minimal medium. Addition of the osmoprotectant glycine betaine to the medium completely abolished the osmotic sensitivity phenotype of the ctc mutant. Altogether, these results suggest that the Ctc protein of L. monocytogenes is involved in osmotic stress tolerance in the absence of any osmoprotectant in the medium.

Role of Sigma B Factor in the Alkaline Tolerance Response of Listeria monocytogenes 10403S and Cross-Protection against Subsequent Ethanol and Osmotic Stress

2008 ◽  
Vol 71 (7) ◽  
pp. 1481-1485 ◽  
Author(s):  
EFSTATHIOS S. GIOTIS ◽  
MUDCHAREE JULOTOK ◽  
BRIAN J. WILKINSON ◽  
IAN S. BLAIR ◽  
DAVID A. MCDOWELL
Keyword(s):  
Listeria Monocytogenes ◽  
Osmotic Stress ◽  
Surface Cleaning ◽  
Cross Protection ◽  
Ethanol Stress ◽  
Alkaline Ph ◽  
Alkaline Tolerance ◽  
Wide Range ◽  
Type Strains

Many of the considerable abilities of Listeria monocytogenes to persist and grow in a wide range of adverse environmental conditions are thought to be at least partly under the control of the alternative sigma factor (σB), encoded by the sigB gene. However, little is known about the role of this master regulon in the impressive ability of Listeria to persist and grow under conditions of alkaline pH. In this study, Northern blot analysis of parent Listeria mRNA revealed that alkali adaptation (pH 9.5 for 1 h) significantly increased the expression of sigB-derived mRNA. The study included a comparison of the relative survival of mid-exponential populations of adapted and nonadapted parent type (σB expressing) and mutant (not σB expressing, ΔsigB) Listeria strains during subsequent alkaline (pH 12.0), osmotic (25% NaCl, wt/vol), or ethanol (16.5%) stress. Alkali-adapted parent strains were more resistant to pH 12.0 than were adapted ΔsigB type strains, but both alkali-adapted parent and ΔsigB strains were more resistant to pH 12.0 than were nonadapted strains. Alkali-adapted parent strains were more resistant to osmotic stress than were adapted ΔsigB type strains. No significant differences in viability were observed between alkali-adapted parent and ΔsigB strains after ethanol stress, suggesting that cross-protection against osmotic stress is mediated by σB whereas cross-protection against ethanol is σB independent. Overall, alkali-induced cross-protection against osmotic and ethanol challenges may have serious implications for food safety and human health because such stress conditions are routinely used as part of food preservation and surface cleaning processes.

scholarly journals To Modulate Survival under Secondary Stress Conditions, Listeria monocytogenes 10403S Employs RsbX To Downregulate σBActivity in the Poststress Recovery Stage or Stationary Phase

2015 ◽  
Vol 82 (4) ◽  
pp. 1126-1135 ◽  
Author(s):  
Ye Xia ◽  
Yongping Xin ◽  
Xiaoliang Li ◽  
Weihuan Fang
Keyword(s):  
Listeria Monocytogenes ◽  
Stationary Phase ◽  
Parent Strain ◽  
Recovery Period ◽  
Negative Regulator ◽  
Secondary Stress ◽  
Initial State ◽  
Recovery Stage ◽  
Content Type ◽  
Primary Stress

ABSTRACTListeria monocytogenesis a saprophytic bacterium that thrives in diverse environments and causes listeriosis via ingestion of contaminated food. RsbX, a putative sigma B (σB) regulator, is thought to maintain the ready state in the absence of stress and reset the bacterium to the initial state in the poststress stage inBacillus subtilis. We wondered whether RsbX is functional inL. monocytogenesunder different stress scenarios. Genetic deletion and complementation of thersbXgene were combined with survival tests and transcriptional and translational analyses of σBexpression in response to stresses. We found that deletion ofrsbXincreased survival under secondary stress following recovery of growth after primary stress or following stationary-phase culturing. The ΔrsbXmutant had higher expression of σBthan its parent strain in the recovery stage following primary sodium stress and in stationary-phase cultures. Apparently, increased σBexpression had contributed to improved survival in the absence of RsbX. There were no significant differences in survival rates or σBexpression levels in response to primary stresses between thersbXmutant and its parent strain during the exponential phase. Therefore, we provide clear evidence that RsbX is a negative regulator ofL. monocytogenesσBduring the recovery period after a primary stress or in the stationary phase, thus affecting its survival under secondary stress.

scholarly journals OnfD, an AraC-Type Transcriptional Regulator Encoded by Rhizobium tropici CIAT 899 and Involved in Nod Factor Synthesis and Symbiosis

2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Pablo del Cerro ◽  
Paula Ayala-García ◽  
Pablo Buzón ◽  
Roger Castells-Graells ◽  
Francisco Javier López-Baena ◽  
...  
Keyword(s):  
Salt Stress ◽  
Osmotic Stress ◽  
Transcriptional Activation ◽  
Structural Model ◽  
Stress Conditions ◽  
Broad Host Range ◽  
Rhizobial Strain ◽  
Rhizobium Tropici ◽  
Symbiotic Interaction ◽  
Content Type

ABSTRACT Rhizobium tropici CIAT 899 is a broad-host-range rhizobial strain that establishes symbiotic interactions with legumes and tolerates different environmental stresses such as heat, acidity, or salinity. This rhizobial strain produces a wide variety of symbiotically active nodulation factors (NF) induced not only by the presence of plant-released flavonoids but also under osmotic stress conditions through the LysR-type transcriptional regulators NodD1 (flavonoids) and NodD2 (osmotic stress). However, the activation of NodD2 under high-osmotic-stress conditions remains elusive. Here, we have studied the role of a new AraC-type regulator (named as OnfD) in the symbiotic interaction of R. tropici CIAT 899 with Phaseolus vulgaris and Lotus plants. We determined that OnfD is required under salt stress conditions for the transcriptional activation of the nodulation genes and therefore the synthesis and export of NF, which are required for a successful symbiosis with P. vulgaris. Moreover, using bacterial two-hybrid analysis, we demonstrated that the OnfD and NodD2 proteins form homodimers and OnfD/NodD2 form heterodimers, which could be involved in the production of NF in the presence of osmotic stress conditions since both regulators are required for NF synthesis in the presence of salt. A structural model of OnfD is presented and discussed. IMPORTANCE The synthesis and export of rhizobial NF are mediated by a conserved group of LysR-type regulators, the NodD proteins. Here, we have demonstrated that a non-LysR-type regulator, an AraC-type protein, is required for the transcriptional activation of symbiotic genes and for the synthesis of symbiotically active NF under salt stress conditions.

scholarly journals A Novel Restriction-Modification System Is Responsible for Temperature-Dependent Phage Resistance in Listeria monocytogenes ECII

2012 ◽  
Vol 78 (6) ◽  
pp. 1995-2004 ◽  
Author(s):  
Jae-Won Kim ◽  
Vikrant Dutta ◽  
Driss Elhanafi ◽  
Sangmi Lee ◽  
Jason A. Osborne ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Low Temperatures ◽  
Phage Resistance ◽  
Type Ii ◽  
Temperature Dependent ◽  
Epidemic Clone ◽  
Modification System ◽  
Content Type ◽  
Restriction Modification System ◽  
Restriction Modification

ABSTRACTListeria monocytogenesepidemic clone II (ECII) strains are unusual in being completely resistant to phage when grown at low temperatures (≤30°C). In the current study we constructed and characterized amariner-based mutant (J46C) of the ECII strain H7550-CdSthat lacked temperature-dependent resistance to phage. The transposon was localized in LMOh7858_2753 (open reading frame [ORF] 2753), a member of a 12-ORF genomic island unique to ECII strains. ORF 2753 and ORF 2754 exhibited homologies to restriction endonucleases and methyltransferases associated with type II restriction-modification (RM) systems.In silico-based predictions of the recognition site for this putative RM system were supported by resistance of DNA from ECII strains to digestion by BfuI, a type II restriction enzyme specific for GTATCC (N6/5). Similarly to J46C, a mutant harboring an in-frame deletion of ORF 2753 was susceptible to phage regardless of temperature of growth (25°C or 37°C). Genetic complementation restored phage resistance in 25°C-grown cells of ORF 2753 mutants. Reverse transcription (RT) and quantitative real-time PCR data suggested enhanced transcription of ORF 2753 at low temperatures (≤25°C) compared to 37°C. In contrast, available transcriptional data suggested that the putative methyltransferase (ORF 2754) was constitutively expressed at all tested temperatures (4 to 37°C). Thus, temperature-dependent resistance ofL. monocytogenesECII to phage is mediated by temperature-dependent expression of the restriction endonuclease associated with a novel RM system (LmoH7) unique to this epidemic clone.

Global Gene Expression of Listeria monocytogenes to Salt Stress

2012 ◽  
Vol 75 (5) ◽  
pp. 906-912 ◽  
Author(s):  
DONGRYEOUL BAE ◽  
CONNIE LIU ◽  
TING ZHANG ◽  
MARCUS JONES ◽  
SCOTT N. PETERSON ◽  
...  
Keyword(s):  
Gene Expression ◽  
Salt Stress ◽  
Listeria Monocytogenes ◽  
Cell Growth ◽  
Expression Profiles ◽  
Brain Heart Infusion ◽  
Global Gene Expression ◽  
Phosphotransferase System ◽  
Transcript Levels ◽  
Qrt Pcr

Outbreaks of listeriosis caused by the ingestion of Listeria-contaminated ready-to-eat foods have been reported worldwide. Many ready-to-eat foods, such as deli meat products, contain high amounts of salt, which can disrupt the maintenance of osmotic balance within bacterial cells. To understand how Listeria monocytogenes adapts to salt stress, we examined the growth and global gene expression profiles of L. monocytogenes strain F2365 under salt stress using oligonucleotide probe-based DNA array and quantitative real-time PCR (qRT-PCR) analyses. The growth of L. monocytogenes in brain heart infusion (BHI) medium with various concentrations of NaCl (2.5, 5, and 10%) was significantly inhibited (P &lt; 0.01) when compared with growth in BHI with no NaCl supplementation. Microarray data indicated that growth in BHI medium with 1.2% NaCl upregulated 4 genes and down-regulated 24 genes in L. monocytogenes, which was confirmed by qRT-PCR. The transcript levels of genes involved in the uptake of glycine betaine/l-proline were increased, whereas genes associated with a putative phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS), metabolic enzymes, and virulence factor were down-regulated. Specifically, the expression levels of PTS transport genes were shown to be dependent on NaCl concentration. To further examine whether the down-regulation of PTS genes is related to decreased cell growth, the transcript levels of genes encoding components of enzyme II, involved in the uptake of various sugars used as the primary carbon source in bacteria, were also measured using qRT-PCR. Our results suggest that the decreased transcript levels of PTS genes may be caused by salt stress or reduced cell growth through salt stress. Here, we report global transcriptional profiles of L. monocytogenes in response to salt stress, contributing to an improved understanding of osmotolerance in this bacterium.

scholarly journals Phosphotransferase System-Dependent Extracellular Growth of Listeria monocytogenes Is Regulated by Alternative Sigma Factors σLand σH

2014 ◽  
Vol 80 (24) ◽  
pp. 7673-7682 ◽  
Author(s):  
Siyun Wang ◽  
Renato H. Orsi ◽  
Silin Tang ◽  
Wei Zhang ◽  
Martin Wiedmann ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Carbon Source ◽  
Parent Strain ◽  
Carbon Sources ◽  
Maximum Growth ◽  
Fine Tuning ◽  
Lag Phase ◽  
Phosphotransferase System ◽  
Phase Duration ◽  
Content Type

ABSTRACTAlternative sigma (σ) factors and phosphotransferase systems (PTSs) play pivotal roles in the environmental adaptation and virulence ofListeria monocytogenes. The growth of theL. monocytogenesparent strain 10403S and 15 isogenic alternative σ factor mutants was assessed in defined minimal medium (DM) with PTS-dependent or non-PTS-dependent carbon sources at 25°C or 37°C. Overall, our results suggested that the regulatory effect of alternative σ factors on the growth ofL. monocytogenesis dependent on the temperature and the carbon source. One-way analysis of variance (one-way ANOVA) showed that the factor “strain” had a significant effect on the maximum growth rate (μmax), lag phase duration (λ), and maximum optical density (ODmax) in PTS-dependent carbon sources (P< 0.05) but not in a non-PTS-dependent carbon source. Also, the ODmaxwas not affected by strain for any of the three PTS-dependent carbon sources at 25°C but was affected by strain at 37°C. Monitoring by quantitative real-time PCR (qRT-PCR) showed that transcript levels forlmo0027, a glucose-glucoside PTS permease (PTSGlc-1)-encoding gene, were higher in the absence of σL, and lower in the absence of σH, than in the parent strain. Our data thus indicate that σLnegatively regulateslmo0027and that the increased μmaxobserved for the ΔsigLstrain in DM with glucose may be associated with increased expression of PTSGlc-1 encoded bylmo0027. Our findings suggest that σHand σLmediate the PTS-dependent growth ofL. monocytogenesthrough complex transcriptional regulations and fine-tuning of the expression of specificptsgenes, includinglmo0027. Our findings also reveal a more important and complex role of alternative σ factors in the regulation of growth in different sugar sources than previously assumed.

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