scholarly journals Stress Resistance and Pathogenicity of Nonthermal-Plasma-Induced Viable-but-Nonculturable Staphylococcus aureus through Energy Suppression, Oxidative Stress Defense, and Immune-Escape Mechanisms

2020 ◽  
Vol 87 (2) ◽  
Author(s):  
Xinyu Liao ◽  
Weicheng Hu ◽  
Donghong Liu ◽  
Tian Ding
Keyword(s):  
Oxidative Stress ◽  
Stress Resistance ◽  
Immune Escape ◽  
Nonthermal Plasma ◽  
Host Cells ◽  
Viable But Nonculturable ◽  
Content Type ◽  
Oxidative Stress Defense ◽  
Vbnc Bacteria ◽  
Potential Risks

ABSTRACT The occurrence of viable-but-nonculturable (VBNC) bacteria poses a potential risk to food safety due to failure in conventional colony detection. In this study, induction of VBNC Staphylococcus aureus was conducted by exposure to an atmospheric-pressure air dielectric barrier discharge-nonthermal-plasma (DBD-NTP) treatment with an applied energy of 8.1 kJ. The stress resistance profiles and pathogenicity of VBNC S. aureus were further evaluated. We found that VBNC S. aureus showed levels of tolerance of heat, acid, and osmosis challenges comparable to those shown by culturable S. aureus, while VBNC S. aureus exhibited enhanced resistance to oxidative and antibiotic stress, relating to the mechanisms of cellular energy depletion, antioxidant response initiation, and multidrug efflux pump upregulation. Regarding pathogenicity, NTP-induced VBNC S. aureus retained the capacity to infect the HeLa host cells. Compared with the culturable counterparts, VBNC S. aureus caused reduced immune responses (Toll-like receptor [TLR], nucleotide-binding oligomerization domain [NOD]) in HeLa cells, which was attributed to suppression of biosynthesis of the recognized surface ligands (e.g., peptidoglycan). Additionally, the proteomic analysis revealed that upregulation of several virulence factors (ClfB, SdrD, SCIN, SasH, etc.) could ensure that VBNC S. aureus would adhere to and internalize into host cells and avoid the host attack. The camouflaged mechanisms described above led to VBNC S. aureus causing less damage to the host cells, and their activity might result in longer intracellular persistence, posing potential risks during NTP processing. IMPORTANCE The consumer demand for freshness and nutrition has accelerated the development of mild decontamination technologies. The incomplete killing of nonthermal (NT) treatments might induce pathogens to enter into a viable-but-nonculturable (VBNC) status as a survival strategy. The use of nonthermal plasma (NTP) as a novel food decontamination technology received increased attention in food industry during recent decades. Our previous work confirmed that the foodborne pathogen S. aureus was induced into VBNC status in response to NTP exposure. This work further revealed the development of stress resistance and virulence retention of NTP-induced VBNC S. aureus through the mechanisms of energy suppression, oxidative stress defense, and immune escape. The data provide fundamental knowledge of the potential risks posed by NTP-induced VBNC S. aureus, which require further parameter optimization of the NTP process or combination with other techniques to avoid the occurrence of VBNC bacteria.

scholarly journals Nonthermal Plasma Induces the Viable-but-Nonculturable State in Staphylococcus aureus via Metabolic Suppression and the Oxidative Stress Response

2019 ◽  
Vol 86 (5) ◽  
Author(s):  
Xinyu Liao ◽  
Donghong Liu ◽  
Tian Ding
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Stress Response ◽  
Nonthermal Plasma ◽  
Energy Allocation ◽  
Oxidative Stress Response ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Content Type ◽  
Energy Dependent

ABSTRACT As a novel nonthermal technology, nonthermal plasma (NTP) has attracted a lot of attention. However, it could induce microorganisms into a viable but nonculturable (VBNC) state, posing a potential risk to food safety and public health. In this study, the molecular mechanisms of VBNC Staphylococcus aureus induced by NTP were investigated. With the use of a propidium monoazide quantitative PCR (PMA-qPCR) technique combined with a plate count method, we confirmed that 8.1 to 24.3 kJ NTP induced S. aureus into a VBNC state at a level of 7.4 to 7.6 log10 CFU/ml. The transcriptomic analysis was conducted and revealed that most energy-dependent physiological activities (e.g., metabolism) were arrested in VBNC S. aureus, while the oxidative stress response-related genes (katA, dps, msrB, msrA, and trxA) were significantly upregulated. In addition, this study showed that the ATP depletion by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) pretreatment could accelerate the formation of VBNC S. aureus. The NTP-generated oxidative stress triggers the staphylococcal oxidative stress response, which consumes part of cellular energy (e.g., ATP). The energy allocation is therefore changed, and the energy assigned for other energy-dependent physiological activities (cell growth and division, etc.) is reduced, subsequently forcing S. aureus into a VBNC state. Therefore, the alterations of energy allocation should be some of the major contributors to the induction of VBNC S. aureus with NTP exposure. This study provides valuable knowledge for controlling the formation of VBNC S. aureus during NTP treatment. IMPORTANCE In recent years, nonthermal plasma (NTP) technology has received a lot of attention as a promising alternative to thermal pasteurization in the food industry. However, little is known about the microbial stress response toward NTP, which could be a potential risk to food safety and impede the development of NTP. A viable but nonculturable (VBNC) state is one of the most common survival strategies employed by microorganisms against external stress. This study investigated the mechanisms of the formation of VBNC Staphylococcus aureus by NTP in a more comprehensive and systematic aspect than had been done before. Our work confirmed that the NTP-generated oxidative stress induced changes in energy allocation as a driving force for the formation of VBNC S. aureus. This study could provide better knowledge for controlling the occurrence of VBNC S. aureus induced by NTP, which could lead to more rational design and ensure the development of safe foods.

scholarly journals Pleiotropic Effects of the P5-Type ATPase SpfA on Stress Response Networks Contribute to Virulence in the Pathogenic Mold Aspergillus fumigatus

mBio ◽  
2021 ◽  
Author(s):  
José P. Guirao-Abad ◽  
Martin Weichert ◽  
Ginés Luengo-Gil ◽  
Sarah Sze Wah Wong ◽  
Vishukumar Aimanianda ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Resistance ◽  
Secretory Pathway ◽  
Pathogenic Fungi ◽  
Antifungal Drugs ◽  
Gene Encoding ◽  
Content Type ◽  
Downstream Target ◽  
P Type ◽  
Er Homeostasis

The fungal UPR is an adaptive signaling pathway in the ER that buffers fluctuations in ER stress but also serves as a virulence regulatory hub in species of pathogenic fungi that rely on secretory pathway homeostasis for pathogenicity. This study demonstrates that the gene encoding the ER-localized P5-type ATPase SpfA is a downstream target of the UPR in the pathogenic mold A. fumigatus and that it works together with a second ER-localized P-type ATPase, SrcA, to support ER homeostasis, oxidative stress resistance, susceptibility to antifungal drugs, and virulence of A. fumigatus .

scholarly journals The Helicobacter pylori CZB Cytoplasmic Chemoreceptor TlpD Forms an Autonomous Polar Chemotaxis Signaling Complex That Mediates a Tactic Response to Oxidative Stress

2016 ◽  
Vol 198 (11) ◽  
pp. 1563-1575 ◽  
Author(s):  
Kieran D. Collins ◽  
Tessa M. Andermann ◽  
Jenny Draper ◽  
Lisa Sanders ◽  
Susan M. Williams ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Helicobacter Pylori ◽  
Molecular Mechanisms ◽  
Reactive Oxygen ◽  
Host Cells ◽  
Oxygen Species ◽  
Content Type ◽  
Signaling Complex ◽  
H Pylori

ABSTRACTCytoplasmic chemoreceptors are widespread among prokaryotes but are far less understood than transmembrane chemoreceptors, despite being implicated in many processes. One such cytoplasmic chemoreceptor isHelicobacter pyloriTlpD, which is required for stomach colonization and drives a chemotaxis response to cellular energy levels. Neither the signals sensed by TlpD nor its molecular mechanisms of action are known. We report here that TlpD functions independently of the other chemoreceptors. When TlpD is the sole chemoreceptor, it is able to localize to the pole and recruits CheW, CheA, and at least two CheV proteins to this location. It loses the normal membrane association that appears to be driven by interactions with other chemoreceptors and with CheW, CheV1, and CheA. These results suggest that TlpD can form an autonomous signaling unit. We further determined that TlpD mediates a repellent chemotaxis response to conditions that promote oxidative stress, including being in the presence of iron, hydrogen peroxide, paraquat, and metronidazole. Last, we found that all testedH. pyloristrains express TlpD, whereas other chemoreceptors were present to various degrees. Our data suggest a model in which TlpD coordinates a signaling complex that responds to oxidative stress and may allowH. pylorito avoid areas of the stomach with high concentrations of reactive oxygen species.IMPORTANCEHelicobacter pylorisenses its environment with proteins called chemoreceptors. Chemoreceptors integrate this sensory information to affect flagellum-based motility in a process called chemotaxis. Chemotaxis is employed during infection and presumably aidsH. pyloriin encountering and colonizing preferred niches. A cytoplasmic chemoreceptor named TlpD is particularly important in this process, and we report here that this chemoreceptor is able to operate independently of other chemoreceptors to organize a chemotaxis signaling complex and mediate a repellent response to oxidative stress conditions.H. pyloriencounters and must cope with oxidative stress during infection due to oxygen and reactive oxygen species produced by host cells. TlpD's repellent response may allow the bacteria to escape niches experiencing inflammation and elevated reactive oxygen species (ROS) production.

scholarly journals Identification of Plasmalogens in the Cytoplasmic Membrane of Bifidobacterium animalis subsp. lactis

2011 ◽  
Vol 78 (3) ◽  
pp. 880-884 ◽  
Author(s):  
Taylor S. Oberg ◽  
Robert E. Ward ◽  
James L. Steele ◽  
Jeff R. Broadbent
Keyword(s):  
Oxidative Stress ◽  
Environmental Stress ◽  
Stress Resistance ◽  
Cell Membranes ◽  
Cytoplasmic Membrane ◽  
Eukaryotic Cell ◽  
Bacterial Membrane ◽  
Membrane Composition ◽  
Content Type ◽  
Bifidobacterium Animalis

ABSTRACTPlasmalogens are ether-linked lipids that may influence oxidative stress resistance of eukaryotic cell membranes. Since bacterial membrane composition can influence environmental stress resistance, we explored the prevalence of plasmalogens in the cytoplasmic membrane ofBifidobacterium animalissubsp.lactis. Results showed plasmalogens are a major component of theB. animalissubsp.lactismembrane.

scholarly journals Proline Metabolism IncreaseskatGExpression and Oxidative Stress Resistance in Escherichia coli

2014 ◽  
Vol 197 (3) ◽  
pp. 431-440 ◽  
Author(s):  
Lu Zhang ◽  
James R. Alfano ◽  
Donald F. Becker
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Mutant Strain ◽  
Stress Resistance ◽  
Proline Metabolism ◽  
Wild Type ◽  
Content Type ◽  
Oxidative Stress Resistance ◽  
Proline Utilization

The oxidation ofl-proline to glutamate in Gram-negative bacteria is catalyzed by the proline utilization A (PutA) flavoenzyme, which contains proline dehydrogenase (PRODH) and Δ1-pyrroline-5-carboxylate (P5C) dehydrogenase domains in a single polypeptide. Previous studies have suggested that aside from providing energy, proline metabolism influences oxidative stress resistance in different organisms. To explore this potential role and the mechanism, we characterized the oxidative stress resistance of wild-type andputAmutant strains ofEscherichia coli. Initial stress assays revealed that theputAmutant strain was significantly more sensitive to oxidative stress than the parental wild-type strain. Expression of PutA in theputAmutant strain restored oxidative stress resistance, confirming that depletion of PutA was responsible for the oxidative stress phenotype. Treatment of wild-type cells with proline significantly increased hydroperoxidase I (encoded bykatG) expression and activity. Furthermore, the ΔkatGstrain failed to respond to proline, indicating a critical role for hydroperoxidase I in the mechanism of proline protection. The global regulator OxyR activates the expression ofkatGalong with several other genes involved in oxidative stress defense. In addition tokatG, proline increased the expression ofgrxA(glutaredoxin 1) andtrxC(thioredoxin 2) of the OxyR regulon, implicating OxyR in proline protection. Proline oxidative metabolism was shown to generate hydrogen peroxide, indicating that proline increases oxidative stress tolerance inE. colivia a preadaptive effect involving endogenous hydrogen peroxide production and enhanced catalase-peroxidase activity.

scholarly journals Role of the Filifactor alocis Hypothetical Protein FA519 in Oxidative Stress Resistance

2021 ◽  
Author(s):  
Ezinne Aja ◽  
Arunima Mishra ◽  
Yuetan Dou ◽  
Hansel M. Fletcher
Keyword(s):  
Oxidative Stress ◽  
Periodontal Disease ◽  
Stress Resistance ◽  
Hypothetical Protein ◽  
Content Type ◽  
Genetic Tools ◽  
Oxidative Stress Resistance ◽  
Filifactor Alocis ◽  
Diagnostic Indicator

Filifactor alocis is an emerging member of the periodontal community and is now proposed to be a diagnostic indicator of periodontal disease. However, due to the lack of genetic tools available to study this organism, not much is known about its virulence attributes.

scholarly journals Farnesol Induces Hydrogen Peroxide Resistance in Candida albicans Yeast by Inhibiting the Ras-Cyclic AMP Signaling Pathway

2010 ◽  
Vol 9 (4) ◽  
pp. 569-577 ◽  
Author(s):  
Aurélie Deveau ◽  
Amy E. Piispanen ◽  
Angelyca A. Jackson ◽  
Deborah A. Hogan
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Candida Albicans ◽  
Adenylate Cyclase ◽  
Signaling Pathway ◽  
Stress Resistance ◽  
Ros Generation ◽  
Signaling Molecule ◽  
Content Type ◽  
Oxidative Stress Resistance

ABSTRACT Farnesol, a Candida albicans cell-cell signaling molecule that participates in the control of morphology, has an additional role in protection of the fungus against oxidative stress. In this report, we show that although farnesol induces the accumulation of intracellular reactive oxygen species (ROS), ROS generation is not necessary for the induction of catalase (Cat1)-mediated oxidative-stress resistance. Two antioxidants, α-tocopherol and, to a lesser extent, ascorbic acid effectively reduced intracellular ROS generation by farnesol but did not alter farnesol-induced oxidative-stress resistance. Farnesol inhibits the Ras1-adenylate cyclase (Cyr1) signaling pathway to achieve its effects on morphology under hypha-inducing conditions, and we demonstrate that farnesol induces oxidative-stress resistance by a similar mechanism. Strains lacking either Ras1 or Cyr1 no longer exhibited increased protection against hydrogen peroxide upon preincubation with farnesol. While we also observed the previously reported increase in the phosphorylation level of Hog1, a known regulator of oxidative-stress resistance, in the presence of farnesol, the hog1/hog1 mutant did not differ from wild-type strains in terms of farnesol-induced oxidative-stress resistance. Analysis of Hog1 levels and its phosphorylation states in different mutant backgrounds indicated that mutation of the components of the Ras1-adenylate cyclase pathway was sufficient to cause an increase of Hog1 phosphorylation even in the absence of farnesol or other exogenous sources of oxidative stress. This finding indicates the presence of unknown links between these signaling pathways. Our results suggest that farnesol effects on the Ras-adenylate cyclase cascade are responsible for many of the observed activities of this fungal signaling molecule.

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.

scholarly journals Staphylococcus aureus Adapts to Oxidative Stress by Producing H2O2-Resistant Small-Colony Variants via the SOS Response

2015 ◽  
Vol 83 (5) ◽  
pp. 1830-1844 ◽  
Author(s):  
Kimberley L. Painter ◽  
Elizabeth Strange ◽  
Julian Parkhill ◽  
Kathleen B. Bamford ◽  
Darius Armstrong-James ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Time Course ◽  
Strand Break ◽  
Host Cells ◽  
Wild Type ◽  
Small Colony Variants ◽  
Content Type ◽  
Dna Double Strand Break ◽  
Small Colony

The development of chronic and recurrentStaphylococcus aureusinfections is associated with the emergence of slow-growing mutants known as small-colony variants (SCVs), which are highly tolerant of antibiotics and can survive inside host cells. However, the host and bacterial factors which underpin SCV emergence during infection are poorly understood. Here, we demonstrate that exposure ofS. aureusto sublethal concentrations of H2O2leads to a specific, dose-dependent increase in the population frequency of gentamicin-resistant SCVs. Time course analyses revealed that H2O2exposure caused bacteriostasis in wild-type cells during which time SCVs appeared spontaneously within theS. aureuspopulation. This occurred via a mutagenic DNA repair pathway that included DNA double-strand break repair proteins RexAB, recombinase A, and polymerase V. In addition to triggering SCV emergence by increasing the mutation rate, H2O2also selected for the SCV phenotype, leading to increased phenotypic stability and further enhancing the size of the SCV subpopulation by reducing the rate of SCV reversion to the wild type. Subsequent analyses revealed that SCVs were significantly more resistant to the toxic effects of H2O2than wild-type bacteria. With the exception of heme auxotrophs, gentamicin-resistant SCVs displayed greater catalase activity than wild-type bacteria, which contributed to their resistance to H2O2. Taken together, these data reveal a mechanism by whichS. aureusadapts to oxidative stress via the production of a subpopulation of H2O2-resistant SCVs with enhanced catalase production.

scholarly journals Inactivation of the Organic Hydroperoxide Stress Resistance Regulator OhrR Enhances Resistance to Oxidative Stress and Isoniazid in Mycobacterium smegmatis

2014 ◽  
Vol 197 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Sankaralingam Saikolappan ◽  
Kishore Das ◽  
Subramanian Dhandayuthapani
Keyword(s):  
Oxidative Stress ◽  
Mutant Strain ◽  
Stress Resistance ◽  
Mycobacterium Smegmatis ◽  
Cumene Hydroperoxide ◽  
Wild Type ◽  
Mobility Shift ◽  
Organic Hydroperoxide ◽  
Content Type ◽  
Protein Levels

The organic hydroperoxide stress resistance regulator (OhrR) is a MarR type of transcriptional regulator that primarily regulates the expression of organic hydroperoxide reductase (Ohr) in bacteria. In mycobacteria, the genes encoding these proteins exist in only a few species, which include the fast-growing organismMycobacterium smegmatis. To delineate the roles of Ohr and OhrR in defense against oxidative stress inM. smegmatis, strains lacking the expression of these proteins were constructed by deleting theohrRandohrgenes, independently and together, through homologous recombination. The OhrR mutant strain (MSΔohrR) showed severalfold upregulation of Ohr expression, which could be observed at both the transcript and protein levels. Similar upregulation of Ohr expression was also noticed in anM. smegmatiswild-type strain (MSWt) induced with cumene hydroperoxide (CHP) andt-butyl hydroperoxide (t-BHP). The elevated Ohr expression in MSΔohrR correlated with heightened resistance to oxidative stress due to CHP andt-BHP and to inhibitory effects due to the antituberculosis drug isoniazid (INH). Further, this mutant strain exhibited significantly enhanced survival in the intracellular compartments of macrophages. In contrast, the strains lacking either Ohr alone (MSΔohr) or both Ohr and OhrR (MSΔohr-ohrR) displayed limited or no resistance to hydroperoxides and INH. Additionally, these strains showed no significant differences in intracellular survival from the wild type. Electrophoretic mobility shift assays (EMSAs) revealed that the overexpressed and purified OhrR interacts with theohr-ohrRintergenic region with a greater affinity and this interaction is contingent upon the redox state of the OhrR. These findings suggest that Ohr-OhrR is an important peroxide stress response system inM. smegmatis.

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