Robin L. Brigmon

Antimicrobial properties of diamond-like carbon-silver-platinum nanocomposite thin films

Silver and platinum were incorporated within diamond-like carbon (DLC) thin films using a multicomponent target pulsed laser deposition process. Transmission electron microscopy of the DLC-silver and DLC-platinum composite films reveals that these films self-assemble into particulate nanocomposite structures that possess a high fraction of sp3-hybridized carbon atoms. Nanoindentation testing of DLC-silver nanocomposite films demonstrates that these films possess hardness and Young’s modulus values of approximately 35 and 350 GPa, respectively. DLC-silver-platinum films demonstrated exceptional antimicrobial properties against Staphylococcus and Pseudomonas aeruginosa bacteria.

Atomic layer deposition of nanoporous biomaterials

Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials.

Evaporite Microbial Films, Mats, Microbialites and Stromatolites

Evaporitic environments are found in a variety of depositional settings as early as the Archean. Depositional conditions, microbial communities and mineralogical compositions vary significantly as no two settings are identical. The common thread linking all of the settings is that evaporation exceeds precipitation, resulting in elevated concentrations of cations and anions that are higher than in oceanic systems. The Dead Sea and Storrs Lake are terrestrial examples of two diverse-modern evaporitic settings, as the former is below sea level and the latter is a coastal lake on an island in the Caribbean. Each system varies in water chemistry; the Dead Sea-dissolved ions originate from surface weathered materials, springs, and aquifers while the dissolved ion concentration in Storrs Lake is primarily derived from sea water. Consequently, some of the ions, e.g., Sr, Ba are found at significantly lower concentrations in Storrs Lake than in the Dead Sea. The origin of the dissolved ions are ultimately responsible for the pH of each system, the alkaline versus mildly the acidic. Each system exhibits unique biogeochemical properties as the extreme environments select certain microorganisms. Storrs Lake possesses significant biofilms and stromatolitic deposits; the alkalinity varies, depending on rainfall and storm, activity. The microbial community in Storrs Lake is much more diverse and active than those observed in the Dead Sea. The Dead Sea waters are mildly acidic, lack stromatolites, and possess a lower density of microbial populations. The general absence of microbial and biofilm fossilization is due to the depletion of HCO

Characterization of Bacillus Strains Producing Biosurfactants

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Field Note: Phytoremediation of Chlorinated Ethenes in Seepline Sediments: Tree Selection

and its slightly acidic pH.

Bioprocessing-Based Approach for Bitumen/Water/Fines Separation and Hydrocarbon Recovery from Oil Sands Tailings

Genus Bacillus includes species of industrial, biotechnological, and environmental interest, as well as clinically important strains. In terms of metabolic properties, they present a diverse group, as they can degrade various substrates and produce many molecules, including lipopeptide (LP) biosurfactants. Due to a high interest in biosurfactants for application in different fields, the molecular mechanisms of regulation of the expression of the operons responsible for LPs have been intensively studied. Additionally, many assays have been created to evaluate the use of cost-effective renewable agro-industrial substrates for production. The purpose of the chapter is to provide a comprehensive overview of the results of our studies on identification, characterization, and assessment ability of three Bacillus strains to produce biosurfactants and detection of genes encoding enzymes involved in biosurfactant synthesis. Moreover, the use of alternative substrates to decrease the cost of LP biosurfactant production and some aspects of application of Bacillus spp. as biocontrol agents are discussed.

Influence of triethyl phosphate on phosphatase activity in shooting range soil: Isolation of a zinc-resistant bacterium with an acid phosphatase

Phytoremediation of chlorinated ethene (CE)-contaminated water was investigated at the Savannah River Site in Aiken, SC, USA. Perchloroethylene (PCE) and trichloroethylene (TCE) are present where CE-contaminated groundwater currently outcrops in seepline soils. Results of constructed and planted test cells, filled with soil from a noncontaminated seepline area and supplied with CE-contaminated groundwater (48 ppb) in the field for one season are presented. These test cells were planted with loblolly pines, hybrid poplars, coyote willow, and sweet gum. Cis-dichloroethylene (cDCE), a byproduct from rhizosphere microbial activity, was detected in the soils as well as some tree tissues. All trees tested were found to uptake both PCE and TCE (5–50 pbb/gm dry wt).

The application of bioassays as indicators of petroleum-contaminated soil remediation

Abstract Oil sands are a major source of oil, but their industrial processing generates tailings ponds that are an environmental hazard. The main concerns are mature fine tailings (MFT) composed of residual hydrocarbons, water, and fine clay. Tailings ponds include toxic contaminants such as heavy metals, and toxic organics including naphthenics. Naphthenic acids and polyaromatic hydrocarbons (PAHs) degrade very slowly and pose a long-term threat to surface and groundwater, as they can be transported in the MFT. Research into improved technologies that would enable densification and settling of the suspended particles is ongoing. In batch tests, BioTiger™, a microbial consortium that can metabolize PAHs, demonstrated improved oil sands tailings settling from a Canadian tailings pond. Results also showed, depending on the timing of the measurements, lower suspended solids and turbidity. Elevated total organic carbon was observed in the first 48 hours in the BioTiger™-treated columns and then decreased in overlying water. Oil sands tailings mixed with BioTiger™ showed a two-fold reduction in suspended solids within 24 hours as compared to abiotic controls. The tailings treated with BioTiger™ increased in microbial densities three orders of magnitude from 8.5 × 105 CFU/mL to 1.2 × 108 CFU/mL without any other carbon or energy source added, indicating metabolism of hydrocarbons and other available nutrients. Results demonstrated that bioaugmentation of BioTiger™ increased separation of organic carbon from particles in oil sands and enhanced settling with tailings with improved water quality. Journal style is for Abstract to be less than 200 words, and contain no citations to other sources; please edit as needed

Structural and biological properties of carbon nanotube composite films

Phosphatase-mediated hydrolysis of organic phosphate may be a viable means of stabilizing heavy metals via precipitation as a metal phosphate in bioremediation applications. We investigated the effect of triethyl phosphate (TEP) on soil microbial-phosphatase activity in a heavy-metal contaminated soil. Gaseous TEP has been used at subsurface sites for bioremediation of organic contaminants but not applied in heavy-metal contaminated areas. Little is known about how TEP affects microbial activity in soils and it is postulated that TEP can serve as a phosphate source in nutrient-poor groundwater and soil/sediments. Over a 3-week period, TEP amendment to microcosms containing heavy-metal contaminated soil resulted in increased activity of soil acid-phosphatase and repression of alkaline phosphatase, indicating a stimulatory effect on the microbial population. A soil-free enrichment of microorganisms adapted to heavy-metal and acidic conditions was derived from the TEP-amended soil microcosms using TEP as the sole phosphate source and the selected microbial consortium maintained a high acid-phosphatase activity with repression of alkaline phosphatase. Addition of 5mM zinc to soil-free microcosms had little effect on acid phosphatase but inhibited alkaline phosphatase. One bacterial member from the consortium, identified as Burkholderia cepacia sp., expressed an acid-phosphatase activity uninhibited by high concentrations of zinc and produced a soluble, indigo pigment under phosphate limitation. The pigment was produced in a phosphate-free medium and was not produced in the presence of TEP or phosphate ion, indicative of purple acid-phosphatase types that are pressed by bioavailable phosphate. These results demonstrate that TEP amendment was bioavailable and increased overall phosphatase activity in both soil and soil-free microcosms supporting the possibility of positive outcomes in bioremediation applications.