title: Effects of various heavy metal nanoparticles on Enterococcus hirae and Escherichia coli growth and proton-coupled membrane transport.
abstract: BACKGROUND
  Due 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.
  
  
  RESULTS
  It 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.
  
  
  CONCLUSIONS
  These 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.
authors.affiliation: Research Institute of Biology, Faculty of Biology, Yerevan State University, 1 A. Manoukian Str., 0025, Yerevan, Armenia. Z.Vardanyan@ysu.am.
authors.forename: Zaruhi
authors.initials: Z
authors.lastname: Vardanyan
authors.affiliation: Department of Materials Technology and Structures of Electronic Technique, Institute of Mathematics and High Technologies, Russian-Armenian (Slavonic) University, 123 H. Emin Str., 0051, Yerevan, Armenia. vgev@rau.am.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Gevorkyan
authors.affiliation: "Nano-industry" Concern, 4 Bardin Str., 1 bulk, 119334, Moscow, Russia. nanotech@nanotech.ru.
authors.forename: Michail
authors.initials: M
authors.lastname: Ananyan
authors.affiliation: Department of Medicinal Biochemistry and Biotechnology, Institute of Mathematics and High Technologies, Russian-Armenian (Slavonic) University, 123 H. Emin Str., 0051, Yerevan, Armenia. hvardapetyan@mail.ru.
authors.forename: Hrachik
authors.initials: H
authors.lastname: Vardapetyan
authors.affiliation: Research Institute of Biology, Faculty of Biology, Yerevan State University, 1 A. Manoukian Str., 0025, Yerevan, Armenia. Trchounian@ysu.am.|Department of Medicinal Biochemistry and Biotechnology, Institute of Mathematics and High Technologies, Russian-Armenian (Slavonic) University, 123 H. Emin Str., 0051, Yerevan, Armenia. Trchounian@ysu.am.|Department of Microbiology, Microbes and Plants Biotechnology, Faculty of Biology, Yerevan State University, 1 A. Manoukian Str., 0025, Yerevan, Armenia. Trchounian@ysu.am.
authors.forename: Armen
authors.initials: A
authors.lastname: Trchounian
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003102:Colloids; D004143:Dioctyl Sulfosuccinic Acid / Q000494:pharmacology; D016983:Enterococcus / Q000187:drug effects / Q000254:growth & development*; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development*; D007477:Ions; D053768:Metal Nanoparticles / Q000633:toxicity*; D019216:Metals, Heavy / Q000633:toxicity*; D016062:Porosity; D011188:Potassium / Q000378:metabolism; D011522:Protons; D012834:Silver / Q000633:toxicity; D012996:Solutions; D014025:Titanium / Q000633:toxicity; D015034:Zinc Oxide / Q000633:toxicity
chemical_list: D003102:Colloids; D007477:Ions; D019216:Metals, Heavy; D011522:Protons; D012996:Solutions; D004143:Dioctyl Sulfosuccinic Acid; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D000251:Adenosine Triphosphatases; D011188:Potassium; D015034:Zinc Oxide