scholarly journals Genome-Wide Identification of Resveratrol Intrinsic Resistance Determinants in Staphylococcus aureus

Antibiotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 82
Author(s):  
Liping Liu ◽  
Hanne Ingmer ◽  
Martin Vestergaard
Keyword(s):  
Staphylococcus Aureus ◽  
Stress Response ◽  
Inhibitory Activity ◽  
Bacterial Species ◽  
Dna Integrity ◽  
Intrinsic Resistance ◽  
Potential Health ◽  
Cellular Effects ◽  
Development Of Resistance ◽  
Wide Range

Resveratrol has been extensively studied due to its potential health benefits in multiple diseases, for example, cancer, obesity and cardiovascular diseases. Besides these properties, resveratrol displays inhibitory activity against a wide range of bacterial species; however, the cellular effects of resveratrol in bacteria remain incompletely understood, especially in the human pathogen, Staphylococcus aureus. In this study, we aimed to identify intrinsic resistance genes that aid S. aureus in tolerating the activity of resveratrol. We screened the Nebraska Transposon Mutant Library, consisting of 1920 mutants with inactivation of non-essential genes in S. aureus JE2, for increased susceptibly to resveratrol. On agar plates containing 0.5× the minimum inhibitory concentration (MIC), 17 transposon mutants failed to grow. Of these, four mutants showed a two-fold reduction in MIC, being the clpP protease mutant and three mutants with deficiencies in the electron transport chain (menD, hemB, aroC). The remaining 13 mutants did not show a reduction in MIC, but were confirmed by spot-assays to have increased susceptibility to resveratrol. Several genes were associated with DNA damage repair (recJ, xerC and xseA). Treatment of S. aureus JE2 with sub-inhibitory concentrations of resveratrol did not affect the expression of recJ, xerC and xseA, but increased expression of the SOS–stress response genes lexA and recA, suggesting that resveratrol interferes with DNA integrity in S. aureus. Expression of error-prone DNA polymerases are part of the SOS–stress response and we could show that sub-inhibitory concentrations of resveratrol increased overall mutation frequency as measured by formation of rifampicin resistant mutants. Our data show that DNA repair systems are important determinants aiding S. aureus to overcome the inhibitory activity of resveratrol. Activation of the SOS response by resveratrol could potentially facilitate the development of resistance towards conventional antibiotics in S. aureus.

scholarly journals Global Regulatory Impact of ClpP Protease of Staphylococcus aureus on Regulons Involved in Virulence, Oxidative Stress Response, Autolysis, and DNA Repair

2006 ◽  
Vol 188 (16) ◽  
pp. 5783-5796 ◽  
Author(s):  
Antje Michel ◽  
Franziska Agerer ◽  
Christof R. Hauck ◽  
Mathias Herrmann ◽  
Joachim Ullrich ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Dna Repair ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Transcriptional Analysis ◽  
Expression Of Genes ◽  
Wide Range ◽  
Genes Encoding ◽  
Regulatory Impact

ABSTRACT Staphylococcus aureus is an important pathogen, causing a wide range of infections including sepsis, wound infections, pneumonia, and catheter-related infections. In several pathogens ClpP proteases were identified by in vivo expression technologies to be important for virulence. Clp proteolytic complexes are responsible for adaptation to multiple stresses by degrading accumulated and misfolded proteins. In this report clpP, encoding the proteolytic subunit of the ATP-dependent Clp protease, was deleted, and gene expression of ΔclpP was determined by global transcriptional analysis using DNA-microarray technology. The transcriptional profile reveals a strong regulatory impact of ClpP on the expression of genes encoding proteins that are involved in the pathogenicity of S. aureus and adaptation of the pathogen to several stresses. Expression of the agr system and agr-dependent extracellular virulence factors was diminished. Moreover, the loss of clpP leads to a complete transcriptional derepression of genes of the CtsR- and HrcA-controlled heat shock regulon and a partial derepression of genes involved in oxidative stress response, metal homeostasis, and SOS DNA repair controlled by PerR, Fur, MntR, and LexA. The levels of transcription of genes encoding proteins involved in adaptation to anaerobic conditions potentially regulated by an Fnr-like regulator were decreased. Furthermore, the expression of genes whose products are involved in autolysis was deregulated, leading to enhanced autolysis in the mutant. Our results indicate a strong impact of ClpP proteolytic activity on virulence, stress response, and physiology in S. aureus.

scholarly journals Microbial contamination of raw meat and its environment in retail shops in Karachi, Pakistan

2010 ◽  
Vol 4 (06) ◽  
pp. 382-388 ◽  
Author(s):  
Nafisa Hassan Ali ◽  
Amber Farooqui ◽  
Adnan Khan ◽  
Ameera Yahya Khan ◽  
Shahana Urooj Kazmi
Keyword(s):  
Staphylococcus Aureus ◽  
Environmental Samples ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Raw Meat ◽  
Food Borne Pathogens ◽  
Food Borne ◽  
Shigella Species ◽  
Wide Range ◽  
Meat Samples

Background: This study was conducted to examine the frequency of contamination in retail meat available in Karachi, Pakistan. Methodology: Raw meat samples (250) and surface swabs (90) from meat processing equipment and the surrounding environment were analyzed for microbiological contamination. Results: Out of 340 samples, 84% were found to be contaminated with bacterial species, including Klebsiella, Enterobacter, Staphylococcus aureus and Bacillus subtilis. A total of 550 (66%) of the bacterial isolates were potential pathogens. Of these, 342 and 208 isolates were from meat and environmental samples respectively. Food-borne pathogens isolated from meat samples included Escherichia coli O157:H7, Listeria, Salmonella Enteritidis and Shigella species whereas environmental samples yielded Staphylococcus aureus and Shigella species. Four strains of Brucella species were also isolated from meat samples. Total aerobic counts ranged between 108 -1010 CFU/g or cm2. Resistance to a wide range of antibiotics was observed. Resistance rates to ampicillin, amoxicillin, novobiocin and cefaclor were from 62 to 75% in general. Thirty-three percent of Salmonella isolates were resistant to ampicillin.  No quinolone resistance was observed. Biofilm formation was observed among 88 (16%) pathogenic bacteria including E. coli, Klebsiella, Enterobacter species and Staphylococcus aureus. Conclusions: Food-borne pathogens found in retail shops could be sources for horizontal contamination of meat. Our data confirm the circulation of antibiotic resistant and biofilm forming pathogens in raw meat and its environment in retail shops in Pakistan, which could play a role in the spread of antimicrobial resistance amongst food-borne bacteria.

scholarly journals Effect of Capsicum grossum L. and Allium cepal L. Juice on some bacterial species isolated from contamiinated vegetable salad

2007 ◽  
Vol 4 (1) ◽  
pp. 35-40
Author(s):  
Baghdad Science Journal
Keyword(s):  
Staphylococcus Aureus ◽  
Bacillus Subtilis ◽  
Inhibitory Activity ◽  
Bacterial Species ◽  
Diffusion Method ◽  
Bacterial Isolates ◽  
Salmonella Spp ◽  
Marked Activity ◽  
Agar Well Diffusion Method

Twenty four bacterial isolates were identified from (10) places for wandering sellers in south Baghdad city (Bayaa garage). They were Staphylococcus aureus (9 isolates), Bacillus subtilis (6 isolates), Salmonella spp. (4 isolates) and Psudomonas aeruginosa (5 isolates). Agar well diffusion method was used to definition sensitivity of the fresh and dried juice of Capsicum grossum L. and Allium cepal L. at different concentrations. The fresh juice had no inhibitory activity against the bacterial isolates in contrast to the fresh juice , dried juice which show marked activity against all bacterial isolates at (30) mg/ml.

scholarly journals Inhibition of the ATP Synthase Eliminates the Intrinsic Resistance of Staphylococcus aureus towards Polymyxins

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Martin Vestergaard ◽  
Katrine Nøhr-Meldgaard ◽  
Martin Saxtorph Bojer ◽  
Christina Krogsgård Nielsen ◽  
Rikke Louise Meyer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Atp Synthase ◽  
Bacterial Infections ◽  
Polymyxin B ◽  
Important Class ◽  
Intrinsic Resistance ◽  
Gram Positive ◽  
Gram Negative ◽  
Bacterial Diseases ◽  
Development Of Resistance

ABSTRACT Staphylococcus aureus is intrinsically resistant to polymyxins (polymyxin B and colistin), an important class of cationic antimicrobial peptides used in treatment of Gram-negative bacterial infections. To understand the mechanisms underlying intrinsic polymyxin resistance in S. aureus, we screened the Nebraska Transposon Mutant Library established in S. aureus strain JE2 for increased susceptibility to polymyxin B. Nineteen mutants displayed at least 2-fold reductions in MIC, while the greatest reductions (8-fold) were observed for mutants with inactivation of either graS, graR, vraF, or vraG or the subunits of the ATP synthase (atpA, atpB, atpG, or atpH), which during respiration is the main source of energy. Inactivation of atpA also conferred hypersusceptibility to colistin and the aminoglycoside gentamicin, whereas susceptibilities to nisin, gallidermin, bacitracin, vancomycin, ciprofloxacin, linezolid, daptomycin, and oxacillin were unchanged. ATP synthase activity is known to be inhibited by oligomycin A, and the presence of this compound increased polymyxin B-mediated killing of S. aureus. Our results demonstrate that the ATP synthase contributes to intrinsic resistance of S. aureus towards polymyxins and that inhibition of the ATP synthase sensitizes S. aureus to this group of compounds. These findings show that by modulation of bacterial metabolism, new classes of antibiotics may show efficacy against pathogens towards which they were previously considered inapplicable. In light of the need for new treatment options for infections with serious pathogens like S. aureus, this approach may pave the way for novel applications of existing antibiotics. IMPORTANCE Bacterial pathogens that cause disease in humans remain a serious threat to public health, and antibiotics are still our primary weapon in treating bacterial diseases. The ability to eradicate bacterial infections is critically challenged by development of resistance to all clinically available antibiotics. Polymyxins constitute an important class of antibiotics for treatment of infections caused by Gram-negative pathogens, whereas Gram-positive bacteria remain largely insusceptible towards class of antibiotics. Here we performed a whole-genome screen among nonessential genes for polymyxin intrinsic resistance determinants in Staphylococcus aureus. We found that the ATP synthase is important for polymyxin susceptibility and that inhibition of the ATP synthase sensitizes S. aureus towards polymyxins. Our study provides novel insights into the mechanisms that limit polymyxin activity against S. aureus and provides valuable targets for inhibitors to potentially enable the use of polymyxins against S. aureus and other Gram-positive pathogens. IMPORTANCE Bacterial pathogens that cause disease in humans remain a serious threat to public health, and antibiotics are still our primary weapon in treating bacterial diseases. The ability to eradicate bacterial infections is critically challenged by development of resistance to all clinically available antibiotics. Polymyxins constitute an important class of antibiotics for treatment of infections caused by Gram-negative pathogens, whereas Gram-positive bacteria remain largely insusceptible towards this class of antibiotics. Here we performed a whole-genome screen among nonessential genes for polymyxin intrinsic resistance determinants in Staphylococcus aureus. We found that the ATP synthase is important for polymyxin susceptibility and that inhibition of the ATP synthase sensitizes S. aureus towards polymyxins. Our study provides novel insights into the mechanisms that limit polymyxin activity against S. aureus and provides valuable targets for inhibitors to potentially enable the use of polymyxins against S. aureus and other Gram-positive pathogens.

scholarly journals Generally Stressed Out Bacteria: Environmental Stress Response Mechanisms in Gram-Positive Bacteria

2020 ◽  
Vol 60 (1) ◽  
pp. 126-133
Author(s):  
Carla Y Bonilla
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Environmental Stress ◽  
Bacterial Species ◽  
Dynamic Environments ◽  
System Level ◽  
Environmental Stress Response ◽  
Gram Positive ◽  
Bacterial Physiology ◽  
Wide Range

Abstract The ability to monitor the environment for toxic chemical and physical disturbances is essential for bacteria that live in dynamic environments. The fundamental sensing mechanisms and physiological responses that allow bacteria to thrive are conserved even if the molecular components of these pathways are not. The bacterial general stress response (GSR) represents a conceptual model for how one pathway integrates a wide range of environmental signals, and how a generalized system with broad molecular responses is coordinated to promote survival likely through complementary pathways. Environmental stress signals such as heat, osmotic stress, and pH changes are received by sensor proteins that through a signaling cascade activate the sigma factor, SigB, to regulate over 200 genes. Additionally, the GSR plays an important role in stress priming that increases bacterial fitness to unrelated subsequent stressors such as oxidative compounds. While the GSR response is implicated during oxidative stress, the reason for its activation remains unknown and suggests crosstalk between environmental and oxidative stress sensors and responses to coordinate antioxidant functions. Systems levels studies of cellular responses such as transcriptomes, proteomes, and metabolomes of stressed bacteria and single-cell analysis could shed light into the regulated functions that protect, remediate, and minimize damage during dynamic environments. This perspective will focus on fundamental stress sensing mechanisms and responses in Gram-positive bacterial species to illustrate their commonalities at the molecular and physiological levels; summarize exciting directions; and highlight how system-level approaches can help us understand bacterial physiology.

The Study of Bacillus Subtils Antimicrobial Activity on Some of the Pathological Isolates

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Hussein A Kadhum ◽  
Thualfakar H Hasan2
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Bacillus Subtilis ◽  
Bacterial Growth ◽  
Broad Spectrum ◽  
Inhibitory Activity ◽  
Bacterial Pathogens ◽  
Inhibitory Ability ◽  
Selection Of

The study involved the selection of two isolates from Bacillus subtilis to investigate their inhibitory activity against some bacterial pathogens. B sub-bacteria were found to have a broad spectrum against test bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. They were about 23-30 mm and less against Klebsiella sp. The sensitivity of some antibodies was tested on the test samples. The results showed that the inhibitory ability of bacterial growth in the test samples using B. subtilis extract was more effective than the antibiotics used.

Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

2017 ◽  
Author(s):  
Jana Shen ◽  
Zhi Yue ◽  
Helen Zgurskaya ◽  
Wei Chen
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Conformational Transition ◽  
Conformational Dynamics ◽  
Proton Release ◽  
Intrinsic Resistance ◽  
Constant Ph ◽  
Wide Range ◽  
Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood. <p><br></p>

scholarly journals In vitro activities of Acacia nilotica (L.) Delile bark fractions against Oral Bacteria, Glucosyltransferase and as antioxidant

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ali Mahmoud Muddathir ◽  
Ebtihal Abdalla M. Mohieldin ◽  
Tohru Mitsunaga
Keyword(s):  
Antioxidant Activity ◽  
Antibacterial Activity ◽  
Gallic Acid ◽  
Crude Extract ◽  
Inhibitory Activity ◽  
Oral Bacteria ◽  
Acacia Nilotica ◽  
Assay Method ◽  
Medicinal Uses ◽  
Wide Range

Abstract Background Dental caries and periodontal disease are the most common chronic infectious oral diseases in the world. Acacia nilotica was commonly known in Sudan as Garad or Sunt has a wide range of medicinal uses. In the present study, antibacterial activity of oral bacteria (Streptococcus sobrinus and Porphyromonas gingivalis), inhibitory activity against glucosyltransferase (GTF) enzyme and antioxidant activity were assayed for methanolic crude extract of A. nilotica bark and its fractions. Methods Methanoilc crude extract of A. nilotica bark was applied to a Sephadex LH-20 column and eluted with methanol, aqueous methanol, and finally aqueous acetone to obtain four fractions (Fr1- Fr4). Furthermore, the crude extract and fractions were subjected to analytical high performance liquid chromatography (HPLC). The crude extract and its fractions were assayed for antibacterial activity against S. sobrinus and P. gingivalis using a microplate dilution assay method to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), as well as GTF inhibition and antioxidant activity using ABTS radical scavenging method. Results Fractions (Fr1 and Fr2) exhibited MIC values of 0.3 mg/ml against the P. gingivalis. Additionally, Fr2 displayed MBC value of 1 mg/ml against two types of bacteria. Fr4 showed an especially potent GTF inhibitory activity with IC50 value of 3.9 μg/ml. Fr1 displayed the best antioxidant activity with IC50 value of 1.8 μg/ml. The main compound in Fr1 was identified as gallic acid, and Fr2 was mostly a mixture of gallic acid and methyl gallate. Conclusions The results obtained in this study provide some scientific rationale and justify the use of this plant for the treatment of dental diseases in traditional medicine. A. nilotica bark, besides their antibacterial potentiality and GTF inhibitory activity, it may be used as adjuvant antioxidants in mouthwashes. Further studies in the future are required to identify the rest of the active compounds.

scholarly journals Trends in Molecular Diagnosis and Diversity Studies for Phytosanitary Regulated Xanthomonas

2021 ◽  
Vol 9 (4) ◽  
pp. 862
Author(s):  
Vittoria Catara ◽  
Jaime Cubero ◽  
Joël F. Pothier ◽  
Eran Bosis ◽  
Claude Bragard ◽  
...  
Keyword(s):  
Molecular Diagnosis ◽  
Bacterial Species ◽  
Management Strategies ◽  
Diagnostic Methods ◽  
Plant Diseases ◽  
Wild Plants ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Wide Range ◽  
Diversity Studies

Bacteria in the genus Xanthomonas infect a wide range of crops and wild plants, with most species responsible for plant diseases that have a global economic and environmental impact on the seed, plant, and food trade. Infections by Xanthomonas spp. cause a wide variety of non-specific symptoms, making their identification difficult. The coexistence of phylogenetically close strains, but drastically different in their phenotype, poses an added challenge to diagnosis. Data on future climate change scenarios predict an increase in the severity of epidemics and a geographical expansion of pathogens, increasing pressure on plant health services. In this context, the effectiveness of integrated disease management strategies strongly depends on the availability of rapid, sensitive, and specific diagnostic methods. The accumulation of genomic information in recent years has facilitated the identification of new DNA markers, a cornerstone for the development of more sensitive and specific methods. Nevertheless, the challenges that the taxonomic complexity of this genus represents in terms of diagnosis together with the fact that within the same bacterial species, groups of strains may interact with distinct host species demonstrate that there is still a long way to go. In this review, we describe and discuss the current molecular-based methods for the diagnosis and detection of regulated Xanthomonas, taxonomic and diversity studies in Xanthomonas and genomic approaches for molecular diagnosis.

scholarly journals Discovery of novel community-relevant small proteins in a simplified human intestinal microbiome

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Hannes Petruschke ◽  
Christian Schori ◽  
Sebastian Canzler ◽  
Sarah Riesbeck ◽  
Anja Poehlein ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Intestinal Microbiota ◽  
De Novo ◽  
Bacterial Species ◽  
Intestinal Microbiome ◽  
Single Strain ◽  
Small Proteins ◽  
Human Intestinal Microbiota ◽  
Wide Range

Abstract Background The intestinal microbiota plays a crucial role in protecting the host from pathogenic microbes, modulating immunity and regulating metabolic processes. We studied the simplified human intestinal microbiota (SIHUMIx) consisting of eight bacterial species with a particular focus on the discovery of novel small proteins with less than 100 amino acids (= sProteins), some of which may contribute to shape the simplified human intestinal microbiota. Although sProteins carry out a wide range of important functions, they are still often missed in genome annotations, and little is known about their structure and function in individual microbes and especially in microbial communities. Results We created a multi-species integrated proteogenomics search database (iPtgxDB) to enable a comprehensive identification of novel sProteins. Six of the eight SIHUMIx species, for which no complete genomes were available, were sequenced and de novo assembled. Several proteomics approaches including two earlier optimized sProtein enrichment strategies were applied to specifically increase the chances for novel sProtein discovery. The search of tandem mass spectrometry (MS/MS) data against the multi-species iPtgxDB enabled the identification of 31 novel sProteins, of which the expression of 30 was supported by metatranscriptomics data. Using synthetic peptides, we were able to validate the expression of 25 novel sProteins. The comparison of sProtein expression in each single strain versus a multi-species community cultivation showed that six of these sProteins were only identified in the SIHUMIx community indicating a potentially important role of sProteins in the organization of microbial communities. Two of these novel sProteins have a potential antimicrobial function. Metabolic modelling revealed that a third sProtein is located in a genomic region encoding several enzymes relevant for the community metabolism within SIHUMIx. Conclusions We outline an integrated experimental and bioinformatics workflow for the discovery of novel sProteins in a simplified intestinal model system that can be generically applied to other microbial communities. The further analysis of novel sProteins uniquely expressed in the SIHUMIx multi-species community is expected to enable new insights into the role of sProteins on the functionality of bacterial communities such as those of the human intestinal tract.

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