scholarly journals The Ixodes scapularis Symbiont Rickettsia buchneri Inhibits Growth of Pathogenic Rickettsiaceae in Tick Cells: Implications for Vector Competence

2022 ◽  
Vol 8 ◽  
Author(s):  
Benjamin Cull ◽  
Nicole Y. Burkhardt ◽  
Xin-Ru Wang ◽  
Cody J. Thorpe ◽  
Jonathan D. Oliver ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Ixodes Scapularis ◽  
Vector Competence ◽  
Gene Clusters ◽  
Selective Advantage ◽  
Inhibitory Effect ◽  
Infection Dynamics ◽  
Antibiotic Effect ◽  
Tick Survival ◽  
Obligate Intracellular Bacteria

Ixodes scapularis is the primary vector of tick-borne pathogens in North America but notably does not transmit pathogenic Rickettsia species. This tick harbors the transovarially transmitted endosymbiont Rickettsia buchneri, which is widespread in I. scapularis populations, suggesting that it confers a selective advantage for tick survival such as providing essential nutrients. The R. buchneri genome includes genes with similarity to those involved in antibiotic synthesis. There are two gene clusters not found in other Rickettsiaceae, raising the possibility that these may be involved in excluding pathogenic bacteria from the tick. This study explored whether the R. buchneri antibiotic genes might exert antibiotic effects on pathogens associated with I. scapularis. Markedly reduced infectivity and replication of the tick-borne pathogens Anaplasma phagocytophilum, R. monacensis, and R. parkeri were observed in IRE11 tick cells hosting R. buchneri. Using a fluorescent plate reader assay to follow infection dynamics revealed that the presence of R. buchneri in tick cells, even at low infection rates, inhibited the growth of R. parkeri by 86–100% relative to R. buchneri-free cells. In contrast, presence of the low-pathogenic species R. amblyommatis or the endosymbiont R. peacockii only partially reduced the infection and replication of R. parkeri. Addition of host-cell free R. buchneri, cell lysate of R. buchneri-infected IRE11, or supernatant from R. buchneri-infected IRE11 cultures had no effect on R. parkeri infection and replication in IRE11, nor did these treatments show any antibiotic effect against non-obligate intracellular bacteria E. coli and S. aureus. However, lysate from R. buchneri-infected IRE11 challenged with R. parkeri showed some inhibitory effect on R. parkeri infection of treated IRE11, suggesting that challenge by pathogenic rickettsiae may induce the antibiotic effect of R. buchneri. This research suggests a potential role of the endosymbiont in preventing other rickettsiae from colonizing I. scapularis and/or being transmitted transovarially. The confirmation that the observed inhibition is linked to R. buchneri's antibiotic clusters requires further investigation but could have important implications for our understanding of rickettsial competition and vector competence of I. scapularis for rickettsiae.

scholarly journals CONSTITUENTS AND INHIBITORY EFFECT ON HUMAN PATHOGENIC BACTERIA OF THE ROOTS OF SCUTELLARIA BAICALENSIS

2019 ◽  
Vol 57 (1) ◽  
pp. 7
Author(s):  
Duc Long Le ◽  
Huu Tung Nguyen ◽  
Thi Thom Nguyen ◽  
Gyung Ja Choi ◽  
Dinh Hoang Vu ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Pathogenic Bacteria ◽  
Inhibitory Effect ◽  
Scutellaria Baicalensis ◽  
Plant Materials ◽  
Chemical Structures ◽  
Human Pathogenic Bacteria ◽  
Antibiotic Effect ◽  
Study Results

Abstract-HCTN_16Methanol extract of the roots of Scutellaria baicalensis effectively inhibited the bacterial growth of human pathogenic bacteria Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 21768 and Bacillus subtilis ATCC 6633 at MICs of 2,000 µg/mL. n-Hexane, ethyl acetate and aqueous residues were prepared by successively partitioning the methanol extract with n-hexane and ethyl acetate. Among them, only ethyl acetate layer showed antibiotic effect; whereas n-hexane and aqueous layers were inactive against tested bacteria. The ethyl acetate residue was fractionated by silica gel column chromatography to afford three flavonoids and an oligosaccharide. Their chemical structures were elucidated as wogonin (SB1), baicalein (SB4), baicalin (SB5) and tetrasaccharide (SB10) on the basis of the analysis of NMR and MS spectroscopic data. The isolates were evaluated for in vitro inhibitory effect against human pathogenic bacteria using micro dilution bioassay method. Baicalein (SB4) showed a broad-spectrum inhibition against various human pathogenic bacteria. In particular, it was found to potently inhibit S. aureus ATCC 6538 and B. cereus ATCC 21768 with MICs of 9.5 and 38 µg/mL, respectively. The study results demonstrated antibiotic effect of the extracts from the roots of S. baicalensis and characterization of compounds isolated from the plant materials.

Preliminary in Vitro Investigations on The Inhibitory Activity of The Original Dietary Supplement Oxidal® on Pathogenic Bacterial Strains

2020 ◽  
Vol 11 ◽  
pp. 37-43
Author(s):  
Prof. Teodora P. Popova ◽  
Toshka Petrova ◽  
Ignat Ignatov ◽  
Stoil Karadzhov
Keyword(s):  
Dietary Supplement ◽  
Broad Spectrum ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Clinical Effectiveness ◽  
Inhibitory Effect ◽  
Diffusion Method ◽  
Bacterial Strains ◽  
Microbial Strains

The antimicrobial action of the dietary supplement Oxidal® was tested using the classic Bauer and Kirby agar-gel diffusion method. Clinical and reference strains of Staphylococcus aureus and Escherichia coli were used in the studies. The tested dietary supplement showed a well-pronounced inhibitory effect against the microbial strains commensurable with that of the broad-spectrum chemotherapeutic agent Enrofloxacin and showed even higher activity than the broad spectrum antibiotic Thiamphenicol. The proven inhibitory effect of the tested dietary supplement against the examined pathogenic bacteria is in accordance with the established clinical effectiveness standards for antimicrobial agents.

Evaluation of antibacterial, teratogenicity and antibiofilm effect of sulfated chitosans extracted from marine waste against microorganism

2021 ◽  
pp. 088391152110142
Author(s):  
Velu Gomathy ◽  
Venkatesan Manigandan ◽  
Narasimman Vignesh ◽  
Aavula Thabitha ◽  
Ramachandran Saravanan
Keyword(s):  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Inhibitory Effect ◽  
Diffusion Method ◽  
Marine Litter ◽  
Ionization Time ◽  
Gram Positive Bacteria ◽  
Mineral Components ◽  
Ft Ir

Biofilms play a key role in infectious diseases, as they may form on the surface and persist after treatment with various antimicrobial agents. The Staphylococcus aureus, Klebsiella pneumoniae, S. typhimurium, P. aeruginosa, and Escherichia coli most frequently associated with medical devices. Chitosan sulphate from marine litter (SCH-MW) was extracted and the mineral components were determined using atomic absorption spectroscopy (AAS). The degree of deacetylation (DA) of SCH was predicted 50% and 33.3% in crab and shrimp waste respectively. The elucidation of the structure of the SCH-MW was portrayed using FT-IR and 1H-NMR spectroscopy. The molecular mass of SCH-MW was determined with Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF). The teratogenicity of SCH-MW was characterized by the zebrafish embryo (ZFE) model. Antimicrobial activity of SCH-MW was tested with the agar well diffusion method; the inhibitory effect of SCH-MW on biofilm formation was assessed in 96 flat well polystyrene plates. The result revealed that a low concentration of crab-sulfated chitosan inhibited bacterial growth and significantly reduced the anti-biofilm activity of gram-negative and gram-positive bacteria relatively to shrimp. It is potentially against the biofilm formation of pathogenic bacteria.

scholarly journals High-density transposon libraries utilising outward-oriented promoters identify mechanisms of action and resistance to antimicrobials

2020 ◽  
Vol 367 (22) ◽  
Author(s):  
Chris Coward ◽  
Gopujara Dharmalingham ◽  
Omar Abdulle ◽  
Tim Avis ◽  
Stephan Beisken ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Pathogenic Bacteria ◽  
Selective Advantage ◽  
Mechanisms Of Action ◽  
Over Expression ◽  
E Coli ◽  
Synthase Inhibitor ◽  
Established Technique ◽  
Bacterial Transposon

ABSTRACT The use of bacterial transposon mutant libraries in phenotypic screens is a well-established technique for determining which genes are essential or advantageous for growth in conditions of interest. Standard, inactivating, transposon libraries cannot give direct information about genes whose over-expression gives a selective advantage. We report the development of a system wherein outward-oriented promoters are included in mini-transposons, generation of transposon mutant libraries in Escherichia coli and Pseudomonas aeruginosa and their use to probe genes important for growth under selection with the antimicrobial fosfomycin, and a recently-developed leucyl-tRNA synthase inhibitor. In addition to the identification of known mechanisms of action and resistance, we identify the carbon–phosphorous lyase complex as a potential resistance liability for fosfomycin in E. coli and P. aeruginosa. The use of this technology can facilitate the development of novel mechanism-of-action antimicrobials that are urgently required to combat the increasing threat worldwide from antimicrobial-resistant pathogenic bacteria.

scholarly journals Recombinant transfer in the basic genome ofEscherichia coli

2015 ◽  
Vol 112 (29) ◽  
pp. 9070-9075 ◽  
Author(s):  
Purushottam D. Dixit ◽  
Tin Yau Pang ◽  
F. William Studier ◽  
Sergei Maslov
Keyword(s):  
Common Ancestor ◽  
Recipient Cell ◽  
Gene Clusters ◽  
Selective Advantage ◽  
Last Common Ancestor ◽  
Genome Sequences ◽  
Bacterial Genomes ◽  
Basic Genome ◽  
Single Base Pair ◽  
Generalized Transduction

An approximation to the ∼4-Mbp basic genome shared by 32 strains ofEscherichia colirepresenting six evolutionary groups has been derived and analyzed computationally. A multiple alignment of the 32 complete genome sequences was filtered to remove mobile elements and identify the most reliable ∼90% of the aligned length of each of the resulting 496 basic-genome pairs. Patterns of single base-pair mutations (SNPs) in aligned pairs distinguish clonally inherited regions from regions where either genome has acquired DNA fragments from diverged genomes by homologous recombination since their last common ancestor. Such recombinant transfer is pervasive across the basic genome, mostly between genomes in the same evolutionary group, and generates many unique mosaic patterns. The six least-diverged genome pairs have one or two recombinant transfers of length ∼40–115 kbp (and few if any other transfers), each containing one or more gene clusters known to confer strong selective advantage in some environments. Moderately diverged genome pairs (0.4–1% SNPs) show mosaic patterns of interspersed clonal and recombinant regions of varying lengths throughout the basic genome, whereas more highly diverged pairs within an evolutionary group or pairs between evolutionary groups having >1.3% SNPs have few clonal matches longer than a few kilobase pairs. Many recombinant transfers appear to incorporate fragments of the entering DNA produced by restriction systems of the recipient cell. A simple computational model can closely fit the data. Most recombinant transfers seem likely to be due to generalized transduction by coevolving populations of phages, which could efficiently distribute variability throughout bacterial genomes.

scholarly journals A Real-Time Thermal Sensor System for Quantifying the Inhibitory Effect of Antimicrobial Peptides on Bacterial Adhesion and Biofilm Formation

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2771
Author(s):  
Tobias Wieland ◽  
Julia Assmann ◽  
Astrid Bethe ◽  
Christian Fidelak ◽  
Helena Gmoser ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Real Time ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Bovine Mastitis ◽  
Inhibitory Effect ◽  
Thermal Sensor ◽  
Bacterial Cells ◽  
Static Conditions

The increasing rate of antimicrobial resistance (AMR) in pathogenic bacteria is a global threat to human and veterinary medicine. Beyond antibiotics, antimicrobial peptides (AMPs) might be an alternative to inhibit the growth of bacteria, including AMR pathogens, on different surfaces. Biofilm formation, which starts out as bacterial adhesion, poses additional challenges for antibiotics targeting bacterial cells. The objective of this study was to establish a real-time method for the monitoring of the inhibition of (a) bacterial adhesion to a defined substrate and (b) biofilm formation by AMPs using an innovative thermal sensor. We provide evidence that the thermal sensor enables continuous monitoring of the effect of two potent AMPs, protamine and OH-CATH-30, on surface colonization of bovine mastitis-associated Escherichia (E.) coli and Staphylococcus (S.) aureus. The bacteria were grown under static conditions on the surface of the sensor membrane, on which temperature oscillations generated by a heater structure were detected by an amorphous germanium thermistor. Bacterial adhesion, which was confirmed by white light interferometry, caused a detectable amplitude change and phase shift. To our knowledge, the thermal measurement system has never been used to assess the effect of AMPs on bacterial adhesion in real time before. The system could be used to screen and evaluate bacterial adhesion inhibition of both known and novel AMPs.

scholarly journals Determination of lethal concentration and antibacterial activity of commonly used disinfectants

1970 ◽  
Vol 1 (4) ◽  
pp. 102-105 ◽  
Author(s):  
M Alam ◽  
MM Rahman ◽  
MJ Foysal ◽  
MN Hossain
Keyword(s):  
Methylene Blue ◽  
Pseudomonas Fluorescens ◽  
Potassium Permanganate ◽  
Malachite Green ◽  
Copper Sulfate ◽  
Pathogenic Bacteria ◽  
Labeo Rohita ◽  
Inhibitory Effect ◽  
Lethal Concentration

The toxic effects of four disinfectants viz., copper sulfate (CuSO4), potassium permanganate (KMnO4), methylene blue and malachite green on fish and fish pathogenic bacteria Aeromonas sp., Pseudomonas fluorescens, Edwardsiella sp. and Flavobacterium sp. were investigated. Lethal concentration of the disinfectants to fingerlings of Labeo rohita was determined in aquarium by standard method. Lethal concentration of copper sulfate (CuSO4), potassium permanganate (KMnO4), methylene blue and malachite green against fish were found in 0.75ppm, 7ppm, 6ppm and 0.5ppm at 21.4hrs, 18hrs, 9.5hrs and 1.40hrs, respectively. Methylene blue at 4ppm and 5ppm concentration inhibited the growth of Pseudomonas fluorescens and 6ppm concentration suppressed the growth of Aeromonas sp. Copper sulfate (CuSO4) was effective only against Edwardsiella sp at concentration of 10ppm and 8ppm. Malachite green repressed the growth of all four tasted bacteria at a concentration of 1ppm. Potassium permanganate (KMnO4) was failed to exhibit any inhibitory effect on the bacteria even at 30ppm concentration. DOI: http://dx.doi.org/10.3329/ijns.v1i4.9738 IJNS 2011 1(4): 102-105

scholarly journals Overproduction of Ristomycin A by Activation of a Silent Gene Cluster in Amycolatopsis japonicum MG417-CF17

2014 ◽  
Vol 58 (10) ◽  
pp. 6185-6196 ◽  
Author(s):  
Marius Spohn ◽  
Norbert Kirchner ◽  
Andreas Kulik ◽  
Angelika Jochim ◽  
Felix Wolf ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gene Cluster ◽  
High Performance ◽  
Pathogenic Bacteria ◽  
Genome Mining ◽  
Gene Clusters ◽  
Von Willebrand Disease ◽  
Biosynthesis Gene Cluster ◽  
Content Type ◽  
Bioinformatic Tools

ABSTRACTThe emergence of antibiotic-resistant pathogenic bacteria within the last decades is one reason for the urgent need for new antibacterial agents. A strategy to discover new anti-infective compounds is the evaluation of the genetic capacity of secondary metabolite producers and the activation of cryptic gene clusters (genome mining). One genus known for its potential to synthesize medically important products isAmycolatopsis. However,Amycolatopsis japonicumdoes not produce an antibiotic under standard laboratory conditions. In contrast to mostAmycolatopsisstrains,A. japonicumis genetically tractable with different methods. In order to activate a possible silent glycopeptide cluster, we introduced a gene encoding the transcriptional activator of balhimycin biosynthesis, thebbrgene fromAmycolatopsis balhimycina(bbrAba), intoA. japonicum. This resulted in the production of an antibiotically active compound. Following whole-genome sequencing ofA. japonicum, 29 cryptic gene clusters were identified by genome mining. One of these gene clusters is a putative glycopeptide biosynthesis gene cluster. Using bioinformatic tools, ristomycin (syn. ristocetin), a type III glycopeptide, which has antibacterial activity and which is used for the diagnosis of von Willebrand disease and Bernard-Soulier syndrome, was deduced as a possible product of the gene cluster. Chemical analyses by high-performance liquid chromatography and mass spectrometry (HPLC-MS), tandem mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR) spectroscopy confirmed thein silicoprediction that the recombinantA. japonicum/pRM4-bbrAbasynthesizes ristomycin A.

scholarly journals Aromatic Polyketides from a Symbiotic Strain Aspergillus fumigatus D and Characterization of Their Biosynthetic Gene D8.t287

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 324
Author(s):  
Yi Hua ◽  
Rui Pan ◽  
Xuelian Bai ◽  
Bin Wei ◽  
Jianwei Chen ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Polyketide Synthase ◽  
Gene Knockout ◽  
Gene Clusters ◽  
Inhibitory Effect ◽  
Genomic Feature ◽  
Biosynthetic Gene ◽  
Aromatic Polyketides ◽  
Staphyloccocus Aureus ◽  
Coastal Plant

The chemical investigation of one symbiotic strain, Aspergillus fumigatus D, from the coastal plant Edgeworthia chrysantha Lindl led to the isolation of eight compounds (1–8), which were respectively identified as rubrofusarin B (1), alternariol 9-O-methyl ether (2), fonsecinone D (3), asperpyrone A (4), asperpyrone D (5), fonsecinone B (6), fonsecinone A (7), and aurasperone A (8) by a combination of spectroscopic methods (1D NMR and ESI-MS) as well as by comparison with the literature data. An antimicrobial assay showed that these aromatic polyketides exhibited no remarkable inhibitory effect on Escherichia coli, Staphyloccocus aureus and Candida albicans. The genomic feature of strain D was analyzed, as well as its biosynthetic gene clusters, using antibiotics and Secondary Metabolite Analysis Shell 5.1.2 (antiSMASH). Plausible biosynthetic pathways for dimeric naphtho-γ-pyrones 3–8 were first proposed in this work. A non-reducing polyketide synthase (PKS) gene D8.t287 responsible for the biosynthesis of these aromatic polyketides 1–8 was identified and characterized by target gene knockout experiment and UPLC-MS analysis.

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