BackgroundDue to bacterial resistance to antibiotics there is a need for new antimicrobial agents. In this respect nanoparticles can be used as they have expressed antibacterial activity simultaneously being more reactive compared to their bulk material. The action of zinc (II), titanium (IV), copper (II) and (I) oxides thin films with nanostructured surface and silver nanoscale particles on Enterococcus hirae and Escherichia coli growth and membrane activity was studied by using microbiological, potentiometric and spectrophotometric methods.ResultsIt was revealed that sapphire base plates with deposited ZnO, TiO2, CuO and Cu2O nanoparticles had no effects neither on E. hirae nor E. coli growth both on agar plates and in liquid medium. Concentrated Ag nanoparticles colloid solution markedly affected bacterial growth which was expressed by changing growth properties. E. hirae was able to grow only at <1:200 dilutions of Ag nanoparticles while E. coli grew even at 1:10 dilution. At the same time Ag nanoparticles directly affected membranes, as the FOF1-ATPase activity and H+-coupled transport was changed either (E. coli were less susceptible to nanoparticles compared to E. hirae). Ag nanoparticles increased H+ and K+ transport even in the presence of N,N′-dicyclohexylcarbodiimide (DCCD), inhibitor of FOF1. The stoichiometry of DCCD-inhibited ion fluxes was disturbed.ConclusionsThese results point out to distinguishing antibacterial effects of Ag nanoparticles on different bacteria; the difference between effects can be explained by peculiarities in bacterial membrane structure and properties. H+-K+-exchange disturbance by Ag nanoparticles might be involved in antibacterial effects on E. hirae. The role of FOF1 in antibacterial action of Ag nanoparticles was shown using atpD mutant lacked β subunit in F1.
A mini-hydroponic growing system was employed for seedlings of kudzu vine (Pueraria montana) and contents of isoflavones (daidzein, genistein, daidzin, genistin, and puerarin) from shoot and root parts of seedlings were analyzed quantitatively. In addition, exogenous cork pieces, polymeric adsorbent, XAD-4, and universal elicitor, methyl jasmonate (MeJA), were used to regulate the production of these isoflavones. It was shown that cork pieces up-regulate the production of daidzein and genistein up to seven- and eight-fold greater than the levels obtained for control roots. In contrast, levels of glucosyl conjugates, daidzin and genistin, decrease up to five- and eight-fold, respectively. Cork treatment also induces the excretion of the root isoflavone constituents into the growth medium. Minimal levels of isoflavones are absorbed by the cork pieces. XAD-4 stimulates the production of glucosyl conjugates, daidzin and genistin, in root parts about 1.5-fold greater than that obtained in control roots. These are the highest amounts of daidzin and genistin that are observed (5.101 and 6.759 mg g(-1) dry weight, respectively). In contrast to these two adsorbents, MeJA increases the accumulation of isoflavones in shoot rather than in root parts of seedlings, about three- to four-fold over control levels, with the exception of genistein. These studies reveal new observations on the regulation of isoflavone production in hydroponically grown Pueraria montana plants by two adsorbents (cork pieces and XAD-4) and MeJA elicitor.
BackgroundIn 2017 World Health Organization announced the list of the most dangerous superbugs and among them is Pseudomonas aeruginosa, which is an antibiotic resistant opportunistic human pathogen as well as one of the ‘SKAPE’ pathogens. The central problem is that it affects patients suffering from AIDS, cystic fibrosis, cancer, burn victims etc. P. aeruginosa creates and inhabits surface-associated biofilms. Biofilms increase resistance to antibiotics and host immune responses, because of those current treatments are not effective. It is imperative to find new antibacterial treatment strategies against P. aeruginosa, but detailed molecular properties of the LasR protein are not clearly known to date. In the present study, we tried to analyse the molecular properties of the LasR protein as well as the mode of its interactions with autoinducer (AI) the N-3-oxododecanoyl homoserine lactone (3-0-C12-HSL).ResultsWe performed docking and molecular dynamics (MD) simulations of the LasR protein of P. aeruginosa with the 3-0-C12-HSL ligand. We assessed the conformational changes of the interaction and analysed the molecular details of the binding of the 3-0-C12-HSL with LasR. A new interaction site of the 3-0-C12-HSL with LasR protein was found, which involves interaction with conservative residues from ligand binding domain (LBD), beta turns in the short linker region (SLR) and DNA binding domain (DBD). It will be referenced as the LBD-SLR-DBD bridge interaction or “the bridge”. We have also performed LasR monomer protein docking and found a new form of dimerization.ConclusionsThis study may offer new insights for future experimental studies to detect the interaction of the autoinducer with “the bridge” of LasR protein and a new interaction site for drug design.
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