scholarly journals Fusidic Acid-Resistant Mutants of Salmonella enterica Serovar Typhimurium Have Low Levels of Heme and a Reduced Rate of Respiration and Are Sensitive to Oxidative Stress

2004 ◽  
Vol 48 (10) ◽  
pp. 3877-3883 ◽  
Author(s):  
Mirjana Macvanin ◽  
Andras Ballagi ◽  
Diarmaid Hughes
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Fusidic Acid ◽  
Salmonella Enterica ◽  
Heme Biosynthesis ◽  
Growth Media ◽  
Fluorescence Measurements ◽  
Serovar Typhimurium ◽  
Low Levels ◽  
Reduced Rate

ABSTRACT Mutations in the translation elongation factor G (EF-G) make Salmonella enterica serovar Typhimurium resistant to the antibiotic fusidic acid. Fusr mutants are hypersensitive to oxidative stress and rapidly lose viability in the presence of hydrogen peroxide. We show that this phenotype is associated with reduced activity of two catalase enzymes, HPI (a bifunctional catalase-hydroperoxidase) and HPII (a monofunctional catalase). These catalases require the iron-binding cofactor heme for their activity. Fusr mutants have a reduced rate of transcription of hemA, a gene whose product catalyzes the first committed step in heme biosynthesis. Hypersensitivity of Fusr mutants to hydrogen peroxide is abolished by the presence of δ-aminolevulinic acid, the precursor of heme synthesis, in the growth media and by the addition of glutamate or glutamine, amino acids required for the first step in heme biosynthesis. Fluorescence measurements show that the level of heme in a Fusr mutant is significantly lower than it is in the wild type. Heme is also an essential cofactor of cytochromes in the electron transport chain of respiration. We found that the rate of respiration is reduced significantly in Fusr mutants. Sequestration of divalent iron in the growth media decreases the sensitivity of Fusr mutants to oxidative stress. Taken together, these results suggest that Fusr mutants are hypersensitive to oxidative stress because their low levels of heme reduce both catalase activity and respiration capacity. The sensitivity of Fusr mutants to oxidative stress could be associated with loss of viability due to iron-mediated DNA damage in the presence of hydrogen peroxide. We argue that understanding the specific nature of antibiotic resistance fitness costs in different environments may be a generally useful approach in identifying physiological processes that could serve as novel targets for antimicrobial agents.

scholarly journals Salmonella enterica Serovar Typhimurium DT104 Displays a Rugose Phenotype

2001 ◽  
Vol 67 (9) ◽  
pp. 4048-4056 ◽  
Author(s):  
Yuda A. Anriany ◽  
Ronald M. Weiner ◽  
Judith A. Johnson ◽  
Christian E. De Rezende ◽  
Sam W. Joseph
Keyword(s):  
Oxidative Stress ◽  
Electron Microscopy ◽  
Hydrogen Peroxide ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Low Ph ◽  
Serovar Typhimurium ◽  
Extracellular Substances ◽  
Capsular Material ◽  
Scanning Electron

ABSTRACT Rugose phenotypes, such as those observed in Vibrio cholerae, have increased resistance to chlorine, oxidative stress, and complement-mediated killing. In this study we identified and defined a rugose phenotype in Salmonella entericaserovar Typhimurium DT104 and showed induction only on certain media at 25°C after 3 days of incubation. Incubation at 37°C resulted in the appearance of the smooth phenotype. Observation of the ultrastructure of the rugose form and a stable smooth variant (Stv), which was isolated following a series of passages of the rugose cells, revealed extracellular substances only in cells from the rugose colony. Observation of the extracellular substance by scanning electron microscopy (SEM) was correlated with the appearance of corrugation during development of rugose colony morphology over a 4-day incubation period at 25°C. In addition, the cells also formed a pellicle in liquid broth, which was associated with the appearance of interlacing slime and fibrillar structures, as observed by SEM. The pellicle-forming cells were completely surrounded by capsular material, which bound cationic ferritin, thus indicating the presence of an extracellular anionic component. The rugose cells, in contrast to Stv, showed resistance to low pH and hydrogen peroxide and an ability to form biofilms. Based on these results and analogy to the rugose phenotype in V. cholerae, we propose a possible role for the rugose phenotype in the survival of S. enterica serovar Typhimurium DT104.

Sanitization of Chicken Frames by a Combination of Hydrogen Peroxide and UV Light To Reduce Contamination of Derived Edible Products

2019 ◽  
Vol 82 (11) ◽  
pp. 1896-1900
Author(s):  
A. M. JONES-IBARRA ◽  
C. Z. ALVARADO ◽  
CRAIG D. COUFAL ◽  
T. MATTHEW TAYLOR
Keyword(s):  
Hydrogen Peroxide ◽  
Salmonella Enterica ◽  
Advanced Oxidation Process ◽  
Uv Light ◽  
Disease Outbreaks ◽  
Aerobic Bacteria ◽  
Chicken Carcass ◽  
Serovar Typhimurium ◽  
Uv C ◽  
Water Rinse

ABSTRACT Chicken carcass frames are used to obtain mechanically separated chicken (MSC) for use in other further processed food products. Previous foodborne disease outbreaks involving Salmonella-contaminated MSC have demonstrated the potential for the human pathogen to be transmitted to consumers via MSC. The current study evaluated the efficacy of multiple treatments applied to the surfaces of chicken carcass frames to reduce microbial loads on noninoculated frames and frames inoculated with a cocktail of Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium. Inoculated or noninoculated frames were left untreated (control) or were subjected to treatment using a prototype sanitization apparatus. Treatments consisted of (i) a sterile water rinse, (ii) a water rinse followed by 5 s of UV-C light application, or (iii) an advanced oxidation process (AOP) combining 5 or 7% (v/v) hydrogen peroxide (H2O2) with UV-C light. Treatment with 7% H2O2 and UV-C light reduced numbers of aerobic bacteria by up to 1.5 log CFU per frame (P < 0.05); reductions in aerobic bacteria subjected to other treatments did not statistically differ from one another (initial mean load on nontreated frames: 3.6 ± 0.1 log CFU per frame). Salmonella numbers (mean load on inoculated, nontreated control was 5.6 ± 0.2 log CFU per frame) were maximally reduced by AOP application in comparison with other treatments. No difference in Salmonella reductions obtained by 5% H2O2 (1.1 log CFU per frame) was detected compared with that obtained following 7% H2O2 use (1.0 log CFU per frame). The AOP treatment for sanitization of chicken carcass frames reduces microbial contamination on chicken carcass frames that are subsequently used for manufacture of MSC.

scholarly journals Sanitation of fresh green asparagus and green onions inoculated with Salmonella

2009 ◽  
Vol 27 (No. 6) ◽  
pp. 454-462 ◽  
Author(s):  
M.A. Martínez-Téllez ◽  
F.J. Rodríguez-Leyva ◽  
I.E. Espinoza-Medina ◽  
I. Vargas-Arispuro ◽  
A.A. Gardea ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Exposure Time ◽  
Salmonella Enterica ◽  
Fresh Produce ◽  
Clean Water ◽  
Effective Agent ◽  
Serovar Typhimurium ◽  
Postharvest Handling ◽  
Green Asparagus

The absence of good agricultural and manufacturing practices in the production and postharvest handling of fresh produce, such as green asparagus or green onions increase the contamination risk by biological hazards like Salmonella. The objective of this work was to investigate the efficacy of chlorine (200 and 250 ppm), hydrogen peroxide (1.5% and 2%), and lactic acid (1.5% and 2%) sanitisers during different exposure times (40, 60, and 90 s) on the reduction of <i>Salmonella enterica</i> subspecie <i>enterica</i> serovar Typhimurium in inoculated fresh green asparagus and green onions. Washing with clean water only reduced < 1 log10 CFU/g in both vegetables. The most effective sanitiser evaluated for fresh green asparagus and green onions disinfection appeared to be 2% lactic acid reducing <i>Salmonella</i> growth close to 3 log<sub>10</sub> CFU/g. Hydrogen peroxide was the least effective agent for <i>Salmonella</i> Typhimurium reduction. No effect was observed of the exposure time of inoculated product to sanitiser up to 90 seconds. These results confirm that lactic acid could be used as an alternative for fresh green asparagus and green onions sanitation.

scholarly journals Sub-Inhibitory Fosmidomycin Exposures Elicits Oxidative Stress in Salmonella enterica Serovar typhimurium LT2

PLoS ONE ◽  
2014 ◽  
Vol 9 (4) ◽  
pp. e95271 ◽  
Author(s):  
David T. Fox ◽  
Emily N. Schmidt ◽  
Hongzhao Tian ◽  
Suraj Dhungana ◽  
Michael C. Valentine ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Serovar Typhimurium

DsrA confers resistance to oxidative stress in Salmonella enterica serovar Typhimurium

Food Control ◽  
2021 ◽  
Vol 121 ◽  
pp. 107571
Author(s):  
Rui Dong ◽  
Xiaojie Qin ◽  
Shoukui He ◽  
Xiujuan Zhou ◽  
Yan Cui ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Serovar Typhimurium

scholarly journals Thioredoxin 1 Promotes Intracellular Replication and Virulence of Salmonella enterica Serovar Typhimurium

2006 ◽  
Vol 74 (9) ◽  
pp. 5140-5151 ◽  
Author(s):  
Eva Bjur ◽  
Sofia Eriksson-Ygberg ◽  
Fredrik Åslund ◽  
Mikael Rhen
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Salmonella Enterica ◽  
Nitric Oxide Donor ◽  
Intracellular Replication ◽  
Thioredoxin System ◽  
Serovar Typhimurium ◽  
Thioredoxin 1 ◽  
Disulfide Bond Isomerase

ABSTRACT The effect of the cytoplasmic reductase and protein chaperone thioredoxin 1 on the virulence of Salmonella enterica serovar Typhimurium was evaluated by deleting the trxA, trxB, or trxC gene of the cellular thioredoxin system, the grxA or gshA gene of the glutathione/glutaredoxin system, or the dsbC gene coding for a thioredoxin-dependent periplasmic disulfide bond isomerase. Mutants were tested for tolerance to oxidative and nitric oxide donor substances in vitro, for invasion and intracellular replication in cultured epithelial and macrophage-like cells, and for virulence in BALB/c mice. In these experiments only the gshA mutant, which was defective in glutathione synthesis, exhibited sensitization to oxidative stress in vitro and a small decrease in virulence. In contrast, the trxA mutant did not exhibit any growth defects or decreased tolerance to oxidative or nitric oxide stress in vitro, yet there were pronounced decreases in intracellular replication and mouse virulence. Complementation analyses using defined catalytic variants of thioredoxin 1 showed that there is a direct correlation between the redox potential of thioredoxin 1 and restoration of intracellular replication of the trxA mutant. Attenuation of mouse virulence that was caused by a deficiency in thioredoxin 1 was restored by expression of wild-type thioredoxin 1 in trans but not by expression of a catalytically inactive variant. These results clearly imply that in S. enterica serovar Typhimurium, the redox-active protein thioredoxin 1 promotes virulence, whereas in vitro tolerance to oxidative stress depends on production of glutathione.

scholarly journals Distinct Roles of the Salmonella enterica Serovar Typhimurium CyaY and YggX Proteins in the Biosynthesis and Repair of Iron-Sulfur Clusters

2014 ◽  
Vol 82 (4) ◽  
pp. 1390-1401 ◽  
Author(s):  
Jyoti Velayudhan ◽  
Joyce E. Karlinsey ◽  
Elaine R. Frawley ◽  
Lynne A. Becker ◽  
Margaret Nartea ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Salmonella Enterica ◽  
Active Sites ◽  
Nitrosative Stress ◽  
Iron Sulfur Cluster ◽  
Iron Sulfur Clusters ◽  
Content Type ◽  
Sulfur Cluster ◽  
Iron Sulfur ◽  
Serovar Typhimurium

ABSTRACTLabile [4Fe-4S]2+clusters found at the active sites of many dehydratases are susceptible to damage by univalent oxidants that convert the clusters to an inactive [3Fe-4S]1+form. Bacteria repair damaged clusters in a process that does not requirede novoprotein synthesis or the Isc and Suf cluster assembly pathways. The current study investigates the participation of the bacterial frataxin ortholog CyaY and the YggX protein, which are proposed to play roles in iron trafficking and iron-sulfur cluster repair. Previous reports found that individual mutations incyaYoryggXwere not associated with phenotypic changes inEscherichia coliandSalmonella entericaserovar Typhimurium, suggesting that CyaY and YggX might have functionally redundant roles. However, we have found that individual mutations incyaYoryggXconfer enhanced susceptibility to hydrogen peroxide inSalmonella entericaserovar Typhimurium. In addition, inactivation of thestm3944open reading frame, which is located immediately upstream ofcyaYand which encodes a putative inner membrane protein, dramatically enhances the hydrogen peroxide sensitivity of acyaYmutant. Overexpression of STM3944 reduces the elevated intracellular free iron levels observed in anS. Typhimuriumfurmutant and also reduces the total cellular iron content under conditions of iron overload, suggesting that thestm3944-encoded protein may mediate iron efflux. Mutations incyaYandyggXhave different effects on the activities of the iron-sulfur cluster-containing aconitase, serine deaminase, and NADH dehydrogenase I enzymes ofS. Typhimurium under basal conditions or following recovery from oxidative stress. In addition,cyaYandyggXmutations have additive effects on 6-phosphogluconate dehydratase-dependent growth during nitrosative stress, and acyaYmutation reducesSalmonellavirulence in mice. Collectively, these results indicate that CyaY and YggX play distinct supporting roles in iron-sulfur cluster biosynthesis and the repair of labile clusters damaged by univalent oxidants.Salmonellaexperiences oxidative and nitrosative stress within host phagocytes, and CyaY-dependent maintenance of labile iron-sulfur clusters appears to be important forSalmonellavirulence.

scholarly journals Fusidic Acid-Resistant Mutants of Salmonella enterica Serovar Typhimurium with Low Fitness In Vivo Are Defective in RpoS Induction

2003 ◽  
Vol 47 (12) ◽  
pp. 3743-3749 ◽  
Author(s):  
Mirjana Macvanin ◽  
Johanna Björkman ◽  
Sofia Eriksson ◽  
Mikael Rhen ◽  
Dan I. Andersson ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Fusidic Acid ◽  
Salmonella Enterica ◽  
Antimicrobial Agents ◽  
Relative Fitness ◽  
Infection Model ◽  
Macrophage Infection ◽  
Serovar Typhimurium

ABSTRACT Mutants of Salmonella enterica serovar Typhimurium resistant to fusidic acid (Fusr) have mutations in fusA, the gene encoding translation elongation factor G (EF-G). Most Fusr mutants have reduced fitness in vitro and in vivo, in part explained by mutant EF-G slowing the rate of protein synthesis and growth. However, some Fusr mutants with normal rates of protein synthesis still suffer from reduced fitness in vivo. As shown here, Fusr mutants could be similarly ranked in their relative fitness in mouse infection models, in a macrophage infection model, in their relative hypersensitivity to hydrogen peroxide in vivo and in vitro, and in the amount of RpoS production induced upon entry into the stationary phase. We identify a reduced ability to induce production of RpoS (σs) as a defect associated with Fusr strains. Because RpoS is a regulator of the general stress response, and an important virulence factor in Salmonella, an inability to produce RpoS in appropriate amounts can explain the low fitness of Fusr strains in vivo. The unfit Fusr mutants also produce reduced levels of the regulatory molecule ppGpp in response to starvation. Because ppGpp is a positive regulator of RpoS production, we suggest that a possible cause of the reduced levels of RpoS is the reduction in ppGpp production associated with mutant EF-G. The low fitness of Fusr mutants in vivo suggests that drugs that can alter the levels of global regulators of gene expression deserve attention as potential antimicrobial agents.

scholarly journals The BacterialiprAGene Is Conserved across Enterobacteriaceae, Is Involved in Oxidative Stress Resistance, and Influences Gene Expression in Salmonella enterica Serovar Typhimurium

2016 ◽  
Vol 198 (16) ◽  
pp. 2166-2179 ◽  
Author(s):  
Allison Herman ◽  
Jacquelyn Serfecz ◽  
Alexandra Kinnally ◽  
Kathleen Crosby ◽  
Matthew Youngman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Stress Resistance ◽  
Salmonella Enterica ◽  
Phosphotransferase System ◽  
Protein Activity ◽  
Altered Expression ◽  
Content Type ◽  
Oxidative Stress Resistance ◽  
Serovar Typhimurium

ABSTRACTTheiprAgene (formerly known asyaiVor STM0374) is located in a two-gene operon in theSalmonella entericaserovar Typhimurium genome and is associated with altered expression during spaceflight and rotating-wall-vessel culture conditions that increase virulence. However,iprAis uncharacterized in the literature. In this report, we present the first targeted characterization of this gene, which revealed thatiprAis highly conserved acrossEnterobacteriaceae. We found thatS. Typhimurium,Escherichia coli, andEnterobacter cloacaeΔiprAmutant strains display a multi-log-fold increase in oxidative stress resistance that is complemented using a plasmid-borne wild-type (WT) copy of theS. TyphimuriumiprAgene. This observation was also associated with increased catalase activity, increasedS. Typhimurium survival in macrophages, and partial dependence on thekatEgene and full dependence on therpoSgene. Our results indicate that IprA protein activity is sensitive to deletion of the N- and C-terminal 10 amino acids, while a region that includes amino acids 56 to 80 is dispensable for activity. RNA sequencing (RNA-Seq) analysis revealed several genes altered in expression in theS. Typhimurium ΔiprAmutant strain compared to the WT, including those involved in fimbria formation,spvABCD-mediated virulence, ethanolamine utilization, the phosphotransferase system (PTS) transport, and flagellin phase switching from FlgB to FliC (likely a stochastic event) and several genes of hypothetical or putative function.IMPORTANCEOverall, this work reveals that the conservediprAgene measurably influences bacterial biology and highlights the pool of currently uncharacterized genes that are conserved across bacterial genomes. These genes represent potentially useful targets for bacterial engineering, vaccine design, and other possible applications.

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