Survival of ice nucleation-active and genetically engineered inactive strains of Pseudomonas syringae

The survival of ice nucleation-active (INA) and genetically engineered non-INA strains of Pseudomonas syringae was compared under starvation and freezing conditions. In starvation experiments, both strains displayed similar survival curves and recovery from starvation was nearly identical for the two strains. In freezing experiments, oat seedlings colonized by each strain were subjected to freezing temperatures. Populations of the INA strain increased 15-fold in the 18 hours after oat plants incurred frost damage at {dollar}-{dollar}5 and {dollar}-{dollar}12{dollar}\sp\circ{dollar}C. Plants colonized by the non-INA strain were undamaged at {dollar}-{dollar}5{dollar}\sp\circ{dollar}C and exhibited no changes in population size. As temperatures were lowered, plants colonized by the non-INA strain suffered increased frost damage concomitant with bacterial population increases. At {dollar}-{dollar}12{dollar}\sp\circ{dollar}C, both strains behaved identically. The data show a relationship between frost damage to plants and subsequent increased bacterial population size, indicating a potential competitive advantage for INA strains of P. syringae in mild freezing environments

Evaluation of the Biological Sampling Kit (BiSKit) for Large-Area Surface Sampling

Current surface sampling methods for microbial contaminants are designed to sample small areas and utilize culture analysis. The total number of microbes recovered is low because a small area is sampled, making detection of a potential pathogen more difficult. Furthermore, sampling of small areas requires a greater number of samples to be collected, which delays the reporting of results, taxes laboratory resources and staffing, and increases analysis costs. A new biological surface sampling method, the Biological Sampling Kit (BiSKit), designed to sample large areas and to be compatible with testing with a variety of technologies, including PCR and immunoassay, was evaluated and compared to other surface sampling strategies. In experimental room trials, wood laminate and metal surfaces were contaminated by aerosolization of Bacillus atrophaeus spores, a simulant for Bacillus anthracis, into the room, followed by settling of the spores onto the test surfaces. The surfaces were sampled with the BiSKit, a cotton-based swab, and a foam-based swab. Samples were analyzed by culturing, quantitative PCR, and immunological assays. The results showed that the large surface area (1 m2) sampled with the BiSKit resulted in concentrations of B. atrophaeus in samples that were up to 10-fold higher than the concentrations obtained with the other methods tested. A comparison of wet and dry sampling with the BiSKit indicated that dry sampling was more efficient (efficiency, 18.4%) than wet sampling (efficiency, 11.3%). The sensitivities of detection of B. atrophaeus on metal surfaces were 42 ± 5.8 CFU/m2 for wet sampling and 100.5 ± 10.2 CFU/m2 for dry sampling. These results demonstrate that the use of a sampling device capable of sampling larger areas results in higher sensitivity than that obtained with currently available methods and has the advantage of sampling larger areas, thus requiring collection of fewer samples per site

Prevalence and Antimicrobial Agent Susceptibility of Methicillin-resistant Staphylococcus aureus in Healthy Pediatric Outpatients in Las Vegas

Colonization and infection by community-associated resistant strains of Staphylococcus aureus are being reported in epidemic proportions. The purpose of this study was to determine the local prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization in children and to characterize the MRSA isolates in the laboratory with regard to antimicrobial agent susceptibility patterns, and the presence of the mecA and the Panton-Valentine leukocidin (PVL) genes. Nasal swabs were collected at two pediatric clinics from a total of 505 children during health maintenance visits. A brief questionnaire was administered to collect demographic data and pertinent medical, family, and social history. Samples were cultured onto 2 selective media for S. aureus and MRSA. Potential MRSA isolates were further evaluated by real-time polymerase chain reaction (PCR), and for susceptibility to eight antibiotics by disk diffusion. Culture results showed that MRSA was present in 15 of the 505 specimens (3.0%). Six different antimicrobial susceptibility profiles were observed among the MRSA isolates. PCR amplification results showed that all 15 MRSA isolates were positive for the presence of the mecA gene, and 10 MRSA isolates contained the PVL gene. Understanding local prevalence rates and the role of colonization in infection are needed to develop effective interventions to reduce MRSA infections

Diagnostic and Monitoring CERN Accelerator Controls Infrastructure : The DIAMON Project First Deployment in Operation

The CERN accelerator controls infrastructure spans over several machines and several thousands of devices are used to collect and transmit piece of control data. Each of these remote devices might fail and therefore prevent correct operation. A complete diagnostic and monitoring infrastructure has been developed in order to provide Operation crews with complete and easy to use graphical interface presenting the state of the controls system. Simple agents running in each surveyed item periodically report monitoring information to a central server. Graphical JAVA clients in the operation centers subscribe to this monitoring data and display a view of the current state of the machines. Mouse actions from these clients allows for diagnostic commands to be sent to the agent to get additional details or to repair a faulty situation. This presentation will describe the overall architecture of DIAMON, present the different agents running in the controls system and a few views of the graphical clients. The outcome of the first months in operation of the DIAMON tools will also be presented. Finally, the future plans will be exposed

Effectiveness of a Portable, Large-Area Ultraviolet Germicidal Device

Effective disinfection of the hospital environment is a key component in the prevention of healthcare-associated infections. The objective of this project was to evaluate the effectiveness of an ultraviolet germicidal device in reducing the concentrations of culturable bacteria on indoor surfaces. The ultraviolet germicidal device was installed and operated in four experimental trials conducted in a microbiology research chamber. Agar plates inoculated with known concentrations of two test microorganisms were placed on benches inside the chamber at two distances, 1.5 meters and 3.0 meters from the machine, for exposure times of 5 minutes, 10 minutes, and 20 minutes. With test agar plates directly exposed to ultraviolet radiation, percent reductions were all \u3e99.9% compared with the laboratory control plates. However, with indirect UV exposure, the edge of the plastic petri dishes provided some protection from the UV source, as indicated by the presence of colonies along the edge of the agar plates. Additional research will be conducted to further characterize the device for optimal use in surface decontamination and to determine its effectiveness in reducing airborne culturable bacterial concentrations

Characterization of microbial populations in the subsurface

This task is part of a cooperative agreement between the UNLV Research Foundation and the U.S. Department of Energy (#DE-FC28-04RW12237) titled “Yucca Mountain Groundwater Characterization”. The work was conducted in the Harry Reid Center for Environmental Studies, Microbiology Division of the University of Nevada, Las Vegas from October 1, 2004 to September 30, 2006. The overall goal of this research was to investigate the phenomena that affect the fate and transport of radionuclides in the environment. The purpose of this task (ORD-RF-01), “Characterization of Microbial Activity”, was to develop a molecular biological method for the characterization of the microbial population indigenous to the Yucca Mountain Project site, with emphasis in detection and measurement of species or groups of microorganisms that could be involved in actinide and/or metal reduction, and subsurface transport. To quantify and characterize the microbial populations, including microorganisms that may be viable but are not currently physiologically active, a molecular biological approach was utilized to amplify and detect microbial DNA present in the subsurface. This approach, termed polymerase chain reaction (PCR), results in the amplification of DNA sequences that are unique to the groups of microorganisms of interest. Quantitative PCR (QPCR) assays were developed and used for the measurement of subsurface microbial populations. The protocols were evaluated in laboratory tests involving representative microbial species and genera, and tested by assaying available subsurface samples previously collected from the Yucca Mountain Project site. Other subtasks included Quality Assurance (QA) planning and preparation, and a literature review. This work was subject to the Nevada System of Higher Education (NSHE) QA Program requirements

Emergent spatial patterns of competing benthic and pelagic algae in a river network: A parsimonious basin-scale modeling analysis

Algae, as primary producers in riverine ecosystems, are found in two distinct habitats: benthic and pelagic algae typically prevalent in shallow/small and deep/large streams, respectively. Over an entire river continuum, spatiotemporal patterns of the two algal communities reflect specificity in habitat preference determined by geomorphic structure, hydroclimatic controls, and spatiotemporal heterogeneity in nutrient loads from point- and diffuse-sources. By representing these complex interactions between geomorphic, hydrologic, geochemical, and ecological processes, we present here a new river-network-scale dynamic model (CnANDY) for pelagic (A) and benthic (B) algae competing for energy and one limiting nutrient (phosphorus, P). We used the urbanized Weser River Basin in Germany (7th-order; ~8.4 million population; ~46 K km2) as a case study and analyzed simulations for equilibrium mass and concentrations under steady median river discharge. We also examined P, A, and B spatial patterns in four sub-basins. We found an emerging pattern characterized by scaling of P and A concentrations over stream-order ω, whereas B concentration was described by three distinct phases. Furthermore, an abrupt algal regime shift occurred in intermediate streams from B dominance in ω≤3 to exclusive A presence in ω≥6. Modeled and long-term basin-scale monitored dissolved P concentrations matched well for ω>4, and with overlapping ranges in ω<3. Power-spectral analyses for the equilibrium P, A, and B mass distributions along hydrological flow paths showed stronger clustering compared to geomorphological attributes, and longer spatial autocorrelation distance for A compared to B. We discuss the implications of our findings for advancing hydro-ecological concepts, guiding monitoring, informing management of water quality, restoring aquatic habitat, and extending CnANDY model to other river basins