Project description:The aqueous extract of yerba mate, a South American tea beverage made from Ilex paraguariensis leaves, has demonstrated bactericidal and inhibitory activity against bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). The gas chromatography-mass spectrometry (GC-MS) analysis of two unique fractions of yerba mate aqueous extract revealed 8 identifiable small molecules in those fractions with antimicrobial activity. For a more comprehensive analysis, a data analysis pipeline was assembled to prioritize compounds for antimicrobial testing against both MRSA and methicillin-sensitive S. aureus using forty-two unique fractions of the tea extract that were generated in duplicate, assayed for activity, and analyzed with GC-MS. As validation of our automated analysis, we checked our predicted active compounds for activity in literature references and with used authentic standards to test for antimicrobial activity. 3,4-dihydroxybenzaldehyde showed the most antibacterial activity against MRSA at low concentrations in our bioassays. In addition, quinic acid and quercetin were identified using random forests analysis and 5-hydroxy pipecolic acid was identified using linear discriminant analysis. We additionally also generated a ranked list of unidentified compounds that may contribute to the antimicrobial activity of yerba mate against MRSA. Here we utilized GC-MS data to implement an automated analysis that resulted in a ranked list of compounds that likely contribute to the antimicrobial activity of aqueous yerba mate extract against MRSA.
Project description:Brevibacillus sp. SPR20 produced potentially antibacterial substances against MRSA. The synthe-sis of these substances is controlled by their biosynthetic gene clusters. Several mutagenesis methods are used to overcome the restriction of gene regulations when genetic information is ab-sent. Atmospheric and room temperature plasma (ARTP) is a powerful technique to make random mutagenesis for microbial strain improvement. This study utilized an argon-based ARTP to conduct the mutations on SPR20. The positive mutants of 40% occurred. The M27 mutant exhib-ited an increase in anti-MRSA activity when compared to the wild-type, by which the MIC values were 250500 and 500 g/mL, respectively. M27 had genetic stability because it exhibited con-stant activity throughout 15 generations. This mutant had similar morphology and antibiotic susceptibility to the wild-type. Comparative proteomic analysis identified some specific proteins that were upregulated in M27. These proteins were involved in the metabolism of amino acids, cell structure and movement, and catalytic enzymes. These might result in the enhancement of the anti-MRSA activity of the ARTP-treated SPR20 mutant. This study supports the ARTP technology to increase the production of valuable antibacterial agents.
Project description:Baicalin is the main flavonoid component extracted from Scutellaria root. It has multiple potent biological activities, including estrogen-like activity. In our study, we investigated the function of baicalin on mammary stem cell proliferation and mammary development. Our results demonstrated that baicalin significantly accelerates mammary gland development at puberty and during pregnancy; In vitro, baicalin significantly promotes colony formation ability of mammary basal epithelial cells in a three-dimensional (3D) culture system; In vivo, baicalin improved mammary regeneration efficiency in mouse xenograft model. But the mechanism was unknown. Therefore, transcriptome analysis of basal and luminal cells treatment with baicalin was performed.
Project description:Resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high rates of mortality. Antimicrobial peptides are source of molecules for new antimi-crobials development, such as melittin, a fraction of venom from Apis mellifera bee. The aims of this work were to evaluate antibacterial and antibiofilm activity of melittin and its association with oxa-cillin (meltoxa) on MRSA isolates and to investigate mechanisms of action on MRSA by using proteomic analysis.
Project description:To explore the Spermine(Spm)-based antibacterial targets in S. aureus, time course-dependent transcriptome analysis was conducted on Mu50 (MRSA) in the absence and presence of Spm.
Project description:Staphylococcus aureus (S. aureus) is a gram-positive bacterium that causes a wide range of diseases. Terpinen-4-ol is a monoterpene component contained in most plant essential oils with good antibacterial activity. In this study, terpinen-4-ol effectively inhibited 13 strains of S. aureus, and effectively inhibited the biofilm of MRSA. Metabolomics and transcriptomics were used to elucidate changes in MRSA cells exposed to terpinen-4-ol. Terpinen-4-ol significantly changed (greater than a 2- or less than a 2-fold change) the expression of 304 genes and the level of 847 metabolites (greater than a 1.5- or less than a 0.67-fold change) in MRSA. The levels of genes and metabolites related to the valine, leucine and isoleucine biosynthesis metabolism pathway, the purine and pyrimidine metabolism pathway, energy metabolism and β-lactam resistance were dramatically changed in biofilms exposed to terpinen-4-ol. To the best of our knowledge, this research is the first to report the metabolite and expression profiles of MRSA exposed to terpinen-4-ol.
Project description:Safe and efficient antibacterial materials are urgently needed to combat drug-resistant bacteria and biofilm-associated infections. The rational design of nanoparticles for flexible elimination of biofilms by alternative strategies remains challenging. Herein, we propose the fabrication of Janus-structured nanoparticles targeting extracellular polymeric substance to achieve dispersion or near-infrared (NIR) light-activated photothermal elimination of drug-resistant biofilms, respectively. Asymmetrical Janus-structured dextran-bismuth selenide (Dex-BSe) nanoparticles are fabricated by a facile strategy to exploit synergistic effects of both components. The biocompatible dextran domain with the maximum exposure endows the Janus nanoparticles with biofilm penetration, targeting, and dispersion functions. Interestingly, Janus Dex-BSe nanoparticles realize enhanced dispersal of biofilms over time compared with dextran nanoparticles while the underlying molecular mechanisms are further revealed by RNA-sequencing transcriptomics analysis. Alternatively, taking advantage of the preferential accumulation of nanoparticles at infection sites, the self-propelled active motion induced by the unique Janus structure enhances the photothermal killing effect under NIR light irradiation, thereby eradicating the biofilm. Given these favorable features, the antibiofilm activity of Janus Dex-BSe against methicillin-resistant Staphylococcus aureus (MRSA) was first validated in vitro. More importantly, the flexible application of Janus Dex-BSe nanoparticles for biofilm removal or NIR-triggered eradication in vivo was demonstrated by MRSA-infected mouse excisional wound model and abscess model, respectively. The currently developed Janus nanoplatform holds great promise for the efficient elimination of drug-resistant biofilms in diverse antibacterial scenarios.
Project description:<p>The discovery of antibiotics has led to the effective treatment of bacterial infections that were otherwise fatal and has had a transformative effect on modern medicine. Teixobactin is an unusual depsipeptide natural product that was recently discovered from a previously unculturable soil bacterium which is active against several Gram-positive pathogens, including methicillin- resistant Staphylococcus aureus and vancomycin-resistant Enterococci. One of the key attractive features of teixobactin as an antibiotic lead is that resistance could not be generated in a laboratory setting against S. aureus. This is proposed to be a result of the mechanism of action that involves binding to essential bacterial cell wall synthesis building blocks lipid II and lipid III.</p><p>In the present study, metabolomics was used to investigate the potential metabolic pathways and mode of action involved in mechanisms of antibacterial activity and bacterial killing of the synthetic teixobactin analog Leu10-teixobactin against an MRSA strain, S. aureus ATCC700699. The metabolomes of S. aureus ATCC700699 cells were compared at 1, 3 and 6 h following treatment with Leu10-teixobactin (0.5 µg/ml, i.e. 0.5x MIC) and the untreated controls. Leu10-teixobactin significantly perturbed bacterial membrane lipids (glycerophospholipids and fatty acids), peptidoglycan (lipid I and II) metabolism and cell wall teichoic acid (lipid III) biosynthesis as early as after 1 h of treatment reflecting an initial activity on the cell envelope. Concordant with its time-dependent antibacterial killing action, Leu10-teixobactin caused more perturbations in the levels of key intermediates in pathways of amino-sugar and nucleotide-sugar metabolism and their downstream peptidoglycan and teichoic acid biosynthesis at 3 and 6 h. Significant perturbations in arginine metabolism and interrelated tricarboxylic acid cycle, histidine metabolism, pantothenate and Coenzyme A biosynthesis were also observed at 3 and 6 h.</p><p>To conclude, this is the first study to provide novel metabolomics mechanistic information which lends to support the development of teixobactin as an antibacterial drug for the treatment of multi-drug resistant Gram-positive infections.</p>
Project description:Rhodomyrtone, purified from Rhodomyrtus tomentosa (Aiton) Hassk, exhibits a high degree of potency against methicillin-resistant Staphylococcus aureus (MRSA). We recently demonstrated that exposure of MRSA to a subinhibitory concentration (0.174 µg/ml) of rhodomyrtone resulted in the alteration of expression of several functional classes of bacterial proteins. To provide further insight into the antibacterial mode of action of this compound, we determined the impact of exposure to rhodomyrtone on the gene transcriptional profile of MRSA using microarray analysis. Exposure of MRSA to subinhibitory concentrations (0.5MIC; 0.5 µg/ml) of rhodomyrtone revealed significant modulation of gene expression, with induction of 64 genes and repression of 35 genes. Prominent changes in response to exposure to rhodomyrtone involved genes encoding proteins essential to metabolic pathways and processes such as amino acid metabolism, membrane function, ATP-binding cassette (ABC) transportation and lipoprotein and nucleotide metabolism. Genes involved in the synthesis of the aspartate family of amino acids, in particular proteins encoded by the dap operon were prominent. The diaminopimelate (DAP) biosynthetic pathway is the precursor of lysine synthesis and is essential for peptidoglycan biosynthesis. However, phenotypic analysis of the peptidoglycan amino acid content of rhodomyrtone-treated MRSA did not differ significantly from that extracted from control cells. Genes involved in the biosynthesis of amino acids and peptidoglycan, and a high affinity ATP-driven K (+) transport system, were investigated by quantitative reverse transcription-PCR (qRT-PCR) using EMRSA-16 1, 4, or 18 h after exposure to rhodomyrtone and in general the data concurred with that obtained by microarray, highlighting the relevance of the DAP biosynthetic pathway to the mode of action of rhodomyrtone. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-136]
Project description:Type I interferons were discovered as the primary antiviral cytokines and are now known to serve critical functions in host defense against bacterial pathogens. Accordingly, established mediators of interferon antiviral activity may mediate previously unrecognized antibacterial functions. RNase-L is the terminal component of an RNA decay pathway that is an important mediator of interferon-induced antiviral activity. Here we identify a novel role for RNase-L in the host antibacterial response. RNase-L-/- mice exhibited a dramatic increase in mortality following challenge with Bacillus anthracis and Escherichia coli; this increased susceptibility was due to a compromised immune response resulting in increased bacterial load. Investigation of the mechanisms of RNase-L antibacterial activity indicated that RNase-L is required for the optimal induction of proinflammatory cytokines that play essential roles in host defense from bacterial pathogens. RNase-L also regulated the expression of the endolysosomal protease, cathepsin-E, and endosome-associated activities, that function to eliminate internalized bacteria and may contribute to RNase-L antimicrobial action. Our results reveal a unique role for RNase-L in the antibacterial response that is mediated through multiple mechanisms. As a regulator of fundamental components of the innate immune response, RNase-L represents a viable therapeutic target to augment host defense against diverse microbial pathogens. two strains: wildtype and knockout, three time points: untreated, 2hours, and 8hours. three replication for each group. Totally 18 samples.