Biocidal properties of metal oxide nanoparticles and their halogen adducts.

Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (Delta Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores.

Virucidal properties of metal oxide nanoparticles and their halogen adducts.

Selected metal oxide nanoparticles are capable of strongly adsorbing large amounts of halogens (Cl(2), Br, I(2)) and mixed halogens. These solid adducts are relatively stable thermally, and they can be stored for long periods. However, in the open environment, they are potent biocides.

A multifunctional biocide/sporocide and photocatalyst based on titanium dioxide (TiO2) codoped with silver, carbon, and sulfur.

Composite nanostructured samples of Ag (0.5-20%)/(C, S)-TiO(2) were synthesized and characterized by EDX, XRD, FT-IR, UV-vis, BET, XPS, and zeta potential measurements. Photocatalytic and biocidal tests revealed that the amount of the codoped silver (Ag(+)) in (C, S)-TiO(2) played a crucial, distinctive role in the photodegradation of gas-phase acetaldehyde as well as in the inactivation of Escherichia coli cells and Bacillus subtilis spores.

Reprocessing and sterilization of single-use electrophysiological catheters: removal of organic carbon and protein surface residues.

Although evidence to date indicates that reprocessing electrophysiological (EP) catheters results in clean, sterile devices, some concerns persist with regard to the risk of residual contamination. We examined the ability of a defined reprocessing procedure coupled with a validated sterilization protocol to remove organic carbon and protein residues from worst-case soiled EP catheters resulting in clean, sterile devices. Total organic carbon (TOC) determinations indicated that detergent residues on reprocessed used catheters were nominal and significantly lower than organic carbon levels present on new catheters.

Occurrence of ciprofloxacin-, trimethoprim-sulfamethoxazole-, and vancomycin-resistant bacteria in a municipal wastewater treatment plant.

The occurrence of antibiotic-resistant bacteria was evaluated in aqueous samples obtained from a municipal wastewater treatment plant. Samples collected from the influent, clarifier effluent, and disinfected effluent were assayed for fecal coliforms, E. coli, and enterococci exhibiting resistance to ciprofloxacin, trimethoprim-sulfamethoxazole, and vancomycin.

Biocidal activity of nanocrystalline silver powders and particles.

While the activity of the SMAD powders is lower than that of pure silver nitrate, it has the ability to kill bacteria very effectively and over long periods of time.

Concentrations of fecal bacteria and nutrients in soil surrounding round-bale feeding sites.

An experiment was conducted over 7 mo (January to July 2003) to evaluate fecal bacteria and nutrient concentrations in soil surrounding round-bale feeders at 10 winter feeding sites. Soil samples 15 cm in depth were taken monthly from each site at distances of 3, 12, 21, and 30 m from the feeder. Soil samples were taken before livestock access to the sites (January), during the feeding period (February, March, and April), and after cattle removal from the sites (May, June, and July).

Comparison of bacteriophages for use in iodine inactivation: batch and continuous flow studies.

Inactivation rates in batch studies for four commonly used surrogate bacteriophages were measured in stable aqueous iodine solutions for the purpose of determining which was the most suited to evaluate iodine disinfection efficacy in batch and continuous flow conditions. Two types of group Leviviridae bacteriophages were used, Type I (MS2) and Type II (GA), along with group Microviridae, Phi-X174, and group Tectiviridae, PRD1. Inactivation was compared at iodine doses of 1.

Nanoscale powders and formulations with biocidal activity toward spores and vegetative cells of bacillus species, viruses, and toxins.

Certain formulations of nanoscale powders possess antimicrobial properties. These formulations are made of simple, nontoxic metal oxides such as magnesium oxide (MgO) and calcium oxide (CaO, lime) in nanocrystalline form, carrying active forms of halogens, for example, MgO. Cl2 and MgO.

Effect of microgravity on Escherichia coli and MS-2 bacteriophage disinfection by iodinated resins.

Experiments on chemical disinfection by iodinated resins were conducted on STS 50 (USML-1), which flew a 13 day mission during 1992. Fluid processing apparatus containing microorganisms and iodinated resins was assembled in either Manhattan, Kansas, or Boulder, Colorado, and loaded on-board the Space Shuttle for the mission. Pentaiodide resin was more effective than the triiodide resin against Escherichia coli.

Efficacy of a pentaiodide resin disinfectant on Cryptosporidium parvum (Apicomplexa: Cryptosporidiidae) oocysts in vitro.

The resin-I5 column developed at Kansas State University was tested for efficacy against oocysts of Cryptosporidium parvum (Apicomplexa: Cryptosporidiidae). Cesium chloride gradient-purified oocysts were passed through 1.0-cm-diameter columns with lengths of 2.

Response of a phage modification factor to enhanced production of its target molecule.

Escherichia coli cells with plasmids bearing the valS gene were constructed from the Clark-Carbon collection. Their increased valyl-tRNA synthetase (EC 6.1.

Valyl-tRNA synthetase modification-dependent restriction of bacteriophage T4.

A strain of Escherichia coli, CP 790302, severely restricts the growth of wild-type bacteriophage T4. In broth culture, most infections of single cells are abortive, although a few infected cells exhibit reduced burst sizes. In contrast, bacteriophage T4 mutants impaired in the ability to modify valyl-tRNA synthetase develop normally on this strain.

Cryopreservation of Giardia lamblia with dimethyl sulfoxide using a Dewar flask.

This study examined the effect of varying freezing conditions on the human intestinal parasite Giardia lamblia (Portland-1 strain) using a constant vacuum in a Dewar flask and an ethanol bath to regulate the cooling rate. The cryopreservation of the trophozoite stage was investigated. Dimethyl sulfoxide (Me2SO), the cryoprotective agent of choice, was added directly to Giardia growth medium.

A cloning strategy for the bacteriophage T4 vs gene.

The product of the bacteriophage T4 vs gene, the tau peptide, has been shown to thermally stabilize temperature-sensitive valyl-tRNA synthetase (EC 6.1.1.

Effect of resin disinfectants-I3 and -I5 on Giardia muris and Giardia lamblia.

The resin-I5 column developed in our laboratories rendered aqueous suspensions containing up to 5 X 10(4) cysts of Giardia muris or Giardia lamblia per ml incapable of excystation. The inhibition of excystation was effective at both 4 and 25 degrees C. The addition of Na2S2O3 to column eluates containing cysts appeared to partially reverse the disinfectant action, and the reversal was more pronounced at 4 degrees C than at 25 degrees C.

Mutations in a nonessential viral gene permit bacteriophage T4 to form plaques on Escherichia coli valS ts relA.

During viral development bacteriophage T4 modifies the valyl-transfer RNA synthetase of its host Escherichia coli, but the function of the modification has remained elusive. A strain of Escherichia coli has now been identified which is nonpermissive for wild-type bacteriophage T4, but permissive for bacteriophage mutants impaired in the modification reaction. A comparison with other bacteria suggests that nonpermissiveness is due to synthesis of a thermolabile valyl-transfer RNA synthetase and relaxed control of RNA accumulation.

Analysis of the structure of T4 bacteriophage-modified valyl-tRNA synthetase by limited proteolysis and isoelectric focusing.

The new form of valyl-tRNA synthetase (EC 6.1.1.

Purification and properties of a T4 bacteriophage factor that modifies valyl-tRNA synthetase of Escherichia coli.

After T4 bacteriophage infects Escherichia coli, a peptide tau, produced under the control of a phage gene, binds to the host valyl transfer ribonucleic acid synthetase (EC 6.1.1.

A gene of bacteriophage T4 controlling the modification of host valyl-tRNA synthetase.

Two hydroxylamine-induced mutants of bacteriophage T4 defective in modification of host valyl-tRNA synthetase have been isolated by assay of crude extracts for the activity that is characteristic of the wild-type virus. The mutations define a single gene that is situated between the rI and e genes on the T4 genetic map. This new gene is designated vs for valyl-tRNA synthetase.

Temporal appearance of bacteriophage T4-modified valyl tRNA synthetase in Escherichia coli.

Bacteriophage T4-induced modification of Escherichia coli vlayl-tRNA synthetase (EC 6.1.1.