Cellular interaction of different forms of aluminum nanoparticles in rat alveolar macrophages.

Nanomaterials, with dimensions in the 1-100 nm range, possess numerous potential benefits to society. However, there is little characterization of their effects on biological systems, either within the environment or on human health. The present study examines cellular interaction of aluminum oxide and aluminum nanomaterials, including their effect on cell viability and cell phagocytosis, with reference to particle size and the particle's chemical composition. Experiments were performed to characterize initial in vitro cellular effects of rat alveolar macrophages (NR8383) after exposure to aluminum oxide nanoparticles (Al2O3-NP at 30 and 40 nm) and aluminum metal nanoparticles containing a 2-3 nm oxide coat (Al-NP at 50, 80, and 120 nm). Characterization of the nanomaterials, both as received and in situ, was performed using transmission electron microscopy (TEM), dynamic light scattering (DLS), laser Doppler velocimetry (LDV), and/or CytoViva150 Ultra Resolution Imaging (URI)). Particles showed significant agglomeration in cell exposure media using DLS and the URI as compared to primary particle size in TEM. Cell viability assay results indicate a marginal effect on macrophage viability after exposure to Al2O3-NP at doses of 100 microg/mL for 24 h continuous exposure. Al-NP produced significantly reduced viability after 24 h of continuous exposure with doses from 100 to 250 microg/mL. Cell phagocytotic ability was significantly hindered by exposure to 50, 80, or 120 nm Al-NP at 25 microg/mL for 24 h, but the same concentration (25 microg/mL) had no significant effect on the cellular viability. However, no significant effect on phagocytosis was observed with Al2O3-NP. In summary, these results show that Al-NP exhibit greater toxicity and more significantly diminish the phagocytotic ability of macrophages after 24 h of exposure when compared to Al2O3-NP.

Characterization of microbial contamination in United States Air Force aviation fuel tanks.

Bacteria and fungi, isolated from United States Air Force (USAF) aviation fuel samples, were identified by gas chromatograph fatty acid methyl ester (GC-FAME) profiling and 16S or 18S rRNA gene sequencing. Thirty-six samples from 11 geographically separated USAF bases were collected. At each base, an above-ground storage tank, a refueling truck, and an aircraft wing tank were sampled at the lowest sample point, or sump, to investigate microbial diversity and dispersion within the fuel distribution chain. Twelve genera, including four Bacillus species and two Staphylococcus species, were isolated and identified. Bacillus licheniformis, the most prevalent organism isolated, was found at seven of the 11 bases. Of the organisms identified, Bacillus sp., Micrococcus luteus, Sphinogmonas sp., Staphylococcus sp., and the fungus Aureobasidium pullulans have previously been isolated from aviation fuel samples. The bacteria Pantoea ananatis, Arthrobacter sp., Alcaligenes sp., Kocuria rhizophilia, Leucobacter komagatae, Dietza sp., and the fungus Discophaerina fagi have not been previously reported in USAF aviation fuel. Only at two bases were the same organisms isolated from all three sample points in the fuel supply distribution chain. Isolation of previously undocumented organisms suggests either, changes in aviation fuel microbial community in response to changes in aviation fuel composition, additives and biocide use, or simply, improvements in isolation and identification techniques.

Sequential anaerobic-aerobic treatment of an aquifer contaminated by halogenated organics: field results.

In situ, sequential, anaerobic to aerobic treatment of groundwater removed perchloroethene (PCE, 1.1 microM) and benzene (0.8 microM) from a contaminated aquifer. Neither aerobic nor anaerobic treatment alone successfully degraded both the chlorinated and non-chlorinated organic contaminants in the aquifer. After the sequential treatment, PCE, trichloroethene (TCE), vinyl chloride (VC), chloroethane (CA), and benzene were not detectable in groundwater. Desorption of residual aquifer contaminants was tested by halting the groundwater recirculation and analyzing the groundwater after 3 and 7 weeks. No desorption of the chlorinated contaminants or daughter products was observed in the treated portion of the aquifer. Sequential anaerobic to aerobic treatment was successful in remediating the groundwater at this test site and may have broad applications at other contaminated sites. Over the 4-year course of the project, the predominant microbial environment of the test site varied from aerobic to sulfate-reducing, to methanogenic, and back to aerobic conditions. Metabolically active microbial populations developed under all conditions, demonstrating the diversity and robustness of natural microbial flora in the aquifer.