High Bacterial Concentrations Research Articles

A Research of Reservoir Sediment Solidification Using Biotechnology

At the end of 2010, almost all reservoirs in Taiwan have sedimentation problem. Sedimentation in major reservoirs, such as Wushoh reservoir, had reached 63.73% of its storage capacity in 2009, and must undergo dredging. However, agencies responsible for the final processing stages of reservoir sediments failed to come up with a breakthrough. Limitations established by environmental protection laws also hindered proper dredging of the reservoirs. Hence, further investigation was required for solidifying and reusing reservoir sediments. This research focused on the reuse of Wushoh reservoir sediments. Experimental results showed that when bacteria Bacillus Pastuerii(B.P.) was utilized in sediment solidification, higher bacterial concentrations could induce higher sedimentation of calcium carbonate. In a 70% Urea-CaCl2 medium, a bacterial concentration of 100% resulted in the highest compressive strength that was 30% higher than the control group (bacterial concentration of 0%). Therefore, bacteria can be used to solidify sediments and improve compressive strength. In specimens treated with higher concentrations of bacteria, more square and polygonal crystals were observed via SEM. X-ray powder diffractometer (XRD) analysis showed that bacteria-treated sediments contained calcium carbonate crystals in every stage of processing. Hence, it was shown that bacteria can promote solidification by inducing calcium carbonate sedimentation.

1390 Bacterial Colonization of Preterm Infants: Impact of Biofilm Formation on the Nasogastric Feeding Tubes

BackgroundNowadays, hospitals foment breastfeeding or human donor milk to provide the best feeding option to the preterm infant. This fact may represent a key factor in the initiation and development...

In vivo exposure of Mytilus edulis to living enteric bacteria: a threat for immune competency?

Mussels are widespread in coastal environments and experience various physical, chemical, and bacteriological conditions. Owing to the increase of coastal urbanization, mussels are now commonly exposed not only to indigenous bacteria, but also to enteric bacteria originating from pulsed and chronic sewage discharges into coastal environments. Due to its broad resilience to environmental variations, the blue mussel Mytilus edulis is commonly used as an indicator of environmental quality in bio-monitoring programs. However, since mussel immune system capabilities may be affected by the presence of exogenous fecal bacteria in coastal seawater subjected to sewage discharges, we aimed to determine the effect of in vivo bacterial challenges on mussels' immune competency by using two exogenous enteric bacterial strains, Escherichia coli and Enterococcus faecalis, and an indigenous bacterial strain Vibrio splendidus (as control). Bacterial strains were tested individually, by injection into the posterior adductor muscle at three different cell densities (10(2), 10(3), and 10(4) cells). Unlike classic in vitro experiments using higher bacterial concentrations, neither the enteric bacteria nor the indigenous strain induced significant increase or decrease of either cell-mediated (phagocytosis, reactive oxygen species, and NO(x) production) or humoral components (prophenoloxidase-like, acid phosphatase, and L-leucine-aminopeptidase production) of the immune system. This study demonstrates that, at low concentrations, E. coli and E. faecalis do not represent an additional threat that could impair M. edulis immune competency and, as a consequence, its potential of survival in coastal areas subjected to sewage discharges.

Molecular and microscopic analysis of bacteria and viruses in exhaled breath collected using a simple impaction and condensing method.

Exhaled breath condensate (EBC) is increasingly being used as a non-invasive method for disease diagnosis and environmental exposure assessment. By using hydrophobic surface, ice, and droplet scavenging, a simple impaction and condensing based collection method is reported here. Human subjects were recruited to exhale toward the device for 1, 2, 3, and 4 min. The exhaled breath quickly formed into tiny droplets on the hydrophobic surface, which were subsequently scavenged into a 10 µL rolling deionized water droplet. The collected EBC was further analyzed using culturing, DNA stain, Scanning Electron Microscope (SEM), polymerase chain reaction (PCR) and colorimetry (VITEK 2) for bacteria and viruses.Experimental data revealed that bacteria and viruses in EBC can be rapidly collected using the method developed here, with an observed efficiency of 100 µL EBC within 1 min. Culturing, DNA stain, SEM, and qPCR methods all detected high bacterial concentrations up to 7000 CFU/m3 in exhaled breath, including both viable and dead cells of various types. Sphingomonas paucimobilis and Kocuria variants were found dominant in EBC samples using VITEK 2 system. SEM images revealed that most bacteria in exhaled breath are detected in the size range of 0.5–1.0 µm, which is able to enable them to remain airborne for a longer time, thus presenting a risk for airborne transmission of potential diseases. Using qPCR, influenza A H3N2 viruses were also detected in one EBC sample. Different from other devices restricted solely to condensation, the developed method can be easily achieved both by impaction and condensation in a laboratory and could impact current practice of EBC collection. Nonetheless, the reported work is a proof-of-concept demonstration, and its performance in non-invasive disease diagnosis such as bacterimia and virus infections needs to be further validated including effects of its influencing matrix.

In the Same Boat? Health Risks of Water Recreation Are Not Limited to Full-Contact Activities

Forty years after the Clean Water Act established a goal that the nation’s waters be suitable for recreation, many waterways still fail to meet that standard. Those deemed unsuitable for full-contact recreation are nevertheless used for limited-contact water activities such as boating, kayaking, and fishing. Although several states have started exploring site-specific standards for limited-contact recreation in waterways with high bacterial concentrations, very little is known about whether these activities are safe in such settings. The Chicago Health, Environmental Exposure, and Recreation Study, a prospective cohort study of more than 11,000 users of waterways in and around Chicago, sought to estimate the health risks associated with limited-contact recreation in potentially contaminated waters [EHP 120(2):192–197; Dorevitch et al.]. The study compared health outcomes between people who engaged in limited-contact water recreation in the Chicago Area Waterways System (CAWS), those who engaged in limited-contact recreation in “general-use” waters that had been deemed suitable for full-contact recreation, and a reference group of people who engaged in outdoor recreation near but not in contact with water. The CAWS consists primarily of wastewater, including 300 million gallons received daily from each of two wastewater plants. This effluent is treated with an activated sludge process but is not chemically disinfected. Earlier studies showed levels of Escherichia coli and Enterococcus bacteria were much higher and Cryptosporidium and adenovirus type F were detected more frequently in the CAWS than in samples from the general-use waters. Study participants were interviewed prior to their recreation activity, with followup interviews by phone 2, 5, and 21 days afterward. CAWS users experienced more eye symptoms than those in the reference or general-use water groups, and people who engaged in water recreation activities at all were significantly more likely than the reference group to develop gastrointestinal illness in the first 3 days following recreation. The researchers found no difference in the frequency at which gastrointestinal illness developed between general-use and CAWS users. They speculate that the two groups may have received comparable average doses of ingested pathogens, with CAWS users exposed to waters with higher pathogen densities but general-use users more likely to immerse their heads and faces in the water. There was a higher risk of eye symptoms in CAWS users than in the reference or general-use groups, but no statistical differences existed between the 3 groups for development of respiratory illness, rash, or ear problems. Strengths of the study include its large size and prospective exposure self-assessment, while limitations include the reliance on self-reported health outcomes and the inability to quantify actual exposures to pathogens during recreational activities. The results suggest that, contrary to general assumptions, there are health risks associated with limited-contact recreation in waterways—even in water bodies designated as safe for swimming and other full-contact activities. Kayaking on the CAWS, 2009. Even limited-contact water recreation can result in pathogen exposures.

Microbial Links to Inflammatory Bowel Disease Development: Potential Interventional Strategies in Treatment

The two major forms of Inflammatory Bowel Disease (IBD), Crohn’s disease (CD) and ulcerative colitis (UC), affect an estimated 3.6 million people globally [1]. The main mechanisms responsible for the induction and pathogenesis of IBD remain unknown, but there is a general agreement, those intestinal microbiotas that mediate dysregulation of the immune system resulting in progression and development of IBD, are involved [2]. More recent studies have demonstrated that luminal antigens play an active role, to mediate mucosal immune responses that induce IBD progression. In humans, inflammation is most severe in the part of the gut that contains the highest bacterial concentration [3,4]. It is well known that mice fail to develop colitis or have a reduced severity under germ-free conditions, suggesting a pathologic connection between immune cells and commensal enteric bacteria to develop IBD [5-8]. Due to prolonged mucosal contact in parts of the ileum, rectum and caecum regions, the pathogenic germ(s) may decrease the protective bacteria that induce mucosal permeability and lead to enhanced exposure of bacterial products to Toll-like receptors (TLR), and antigens that directly activate the pathogenic T cell immune responses to induce IBD. This induction also mediates regulatory T cell dysfunction or antigen-presenting cells (APC) that might lead to further decreased tolerance to microbial antigens [9].

Coliform Bacteria: The Effect of Sediments on Decay Rates and on Required Detention Times in Stormwater BMPs

Fecal indicator bacteria, such as total coliforms and E. coli, are a challenge to control in urban and rural stormwater runoff. To assess the challenges of improving bacterial water quality standards in surface waters, microcosm experiments were conducted to assess how decay rates of total coliforms and E. coli are affected by sediments and associated organic matter. Samples were collected at a lake embayment to create laboratory microcosms consisting of different combinations of unsterilized and sterilized water and sediment. Calculated first-order decay rate constants ranged from 0.021 to 0.047 h-1 for total coliforms and 0.017 and 0.037 h-1 for E. coli, depending on how each microcosm was prepared. It is evident that sediment in contact with the water column decreases bacteria decay rate, showing that care should be taken when designing stormwater treatment measures. In addition, high organic carbon content in the sediment temporarily increased bacteria concentrations in the water column. The results demonstrate that stormwater treatment measures, such as extended detention basins and constructed wetlands, must hold water for several days to allow for reduction of bacterial concentrations to acceptable levels. In addition, to troubleshoot detention basins and constructed wetlands for causes of high effluent bacterial concentrations, analyses of sediment, organic carbon, and water column depth should be conducted.

Assembléias de foraminíferos e tecamebas associadas a análises sedimentológicas e microbiológicas no delta do rio Paraíba do Sul, Rio de Janeiro, Brasil

Três setores ambientais foram definidos no delta do rio Paraíba do Sul, localizado no norte do estado do Rio de Janeiro, com base em assembléias de foraminíferos e tecamebas além de análises sedimentológicas e microbiológicas. A análise em DCA demonstrou que o carbono bacteriano e a concentração de sedimentos finos foram as análises ambientais mais influentes na distribuição das assembléias. Setor I - composto dominantemente por espécies de foraminíferos aglutinantes, índice de diversidade variável, atividade metabólica bacteriana em aero e anaerobiose, sedimentação areno-siltosa; Setor II - composto por assembleias mistas de foraminíferos e de tecamebas, apresentando os maiores valores de diversidade, atividade metabólica bacteriana em algumas regiões em aerobiose e sedimentação arenosa pobremente selecionada; Setor III - caracterizado pela ocorrência de somente tecamebas, com altas concentrações de carbono bacteriano e sedimentação dominantemente arenosa pobremente selecionada. Este setor representou o ambiente fluvial. Os resultados refletiram o comportamento hidrodinâmico da área e podem ser utilizados em estudos para diagnóstico ambiental e vulnerabilidade deste ecossistema, além de poder ser utilizados como base em estudos paleoambientais do delta.

Effects of urbanization on stream hydrology and water quality: the Florida Gulf Coast

AbstractAt the global scale, the population density of coastal areas is nearly three times that of inland areas, and consequently, land development represents a threat to coastal ecosystems. It is critical to understand how increasing urbanization affects coastal watersheds. To that end, the objective of this study was to examine the influence of urban development on stream water quality and hydrology in a coastal setting, a scenario that has received less attention than other physiographic regions. Stream hydrologic, physicochemical, and microbial data were collected in watersheds near Apalachicola, Florida with a range of impervious surfaces from 0 to 15%. Watersheds with greater impervious cover exhibited higher pH, specific conductance, and temperature, elevated nutrient concentrations and loads (, and total phosphorus), higher bacterial concentrations (fecal coliform and Escherichia coli), and increased maximum flow and hydrograph flashiness. Different responses to development here compared to other physiographic regions included lower total suspended solid concentrations, higher total dissolved solid concentrations, and a lack of response of base flow to increased urbanization. Additionally, Na+ and Cl− concentrations were elevated to a greater extent than is often the case in non‐coastal areas. In the coming years, urban development is projected to increase substantially in coastal zones and thus there is risk of further stream degradation in coastal watersheds. Copyright © 2011 John Wiley & Sons, Ltd.

Application of an Integrated Community Analysis Approach for Microbial Source Tracking in a Coastal Creek

High fecal indicator bacterial (FIB) concentrations signal urban coastal water quality impairments that can threaten public health. However, FIB (total and fecal coliform plus Enterococcus sp.) concentrations are not specific to human waste, and thus, microbial source tracking (MST) is employed to assess public health risks and remediation alternatives. Currently, water quality diagnosis requires several simultaneous MST assays. Relatively unexplored is a community analysis approach for MST where the overall microbial community composition is compared, through multivariate analysis, to link sources and sinks of microbial pollution. In this research, an urban coastal creek and drain sampling transect, previously diagnosed as human-waste-contaminated, were evaluated for bacterial community composition relative to fecal sources; a laboratory spiking study was also performed to assess method sensitivity and specificity. Multivariate statistical analysis of community profiles clearly distinguished different fecal sources, indicated a high sensitivity for sewage spikes, and confirmed creek contamination sources. This work demonstrates that molecular microbial community analysis combined with appropriate multivariate statistical analyses is an effective addition to the MST tool box.

Accuracy of bacterial DNA testing for central venous catheter-associated bloodstream infection in children with cancer

Central venous catheters (CVCs) are widely used for children with cancer and are a major risk factor for bloodstream infection. Early and specific diagnosis of CVC-associated bloodstream infection allows early targeted treatment, reducing the risk of CVC removal and avoiding the operative risks and trauma of reinsertion, but peripheral vein sampling, as used in adults, improves specificity but is not usually acceptable in children. To improve the detection and treatment of CVC-associated bloodstream infection in children (aged 0-18 years) with cancer admitted with fever. There were four main studies: (1) evaluation of the diagnostic accuracy of a quantitative molecular method for the detection of bacterial deoxyribonucleic acid (DNA), based solely on blood samples drawn through the CVC; (2) analysis of the prognostic risk of CVC removal and duration of intravenous (i.v.) antibiotic treatment days in relation to presenting clinical features, blood culture results and bacterial DNA test results; (3) systematic reviews of treatment options for CVC-associated infection and a questionnaire survey of current practice in paediatric oncology centres; (4) evaluation of the clinical effectiveness of different test-treatment strategies to reduce i.v. antibiotic treatment days and unnecessary CVC removals. (1) The bacterial DNA test detected two-thirds [95% confidence interval (CI) 44% to 83%] of children classified with probable CVC-associated infection - specificity was 88% (95% CI 84% to 92%). Although high bacterial DNA concentrations were associated with subsequent CVC removal and long duration of i.v. antibiotic treatment, the test did not improve the prediction of these outcomes over and above clinical signs of CVC-associated infection combined with blood culture results. (2) High DNA load was predictive of CVC removal and i.v. treatment duration, before blood culture results became available at 48 hours after sampling. (3) There was limited evidence that antibiotic lock treatment reduces the risk of recurrent CVC-associated infection or CVC removal (pooled relative risk 0.7, 95% CI 0.47 to 1.05), but prophylactic use of antimicrobial locks halved the risk of bloodstream infection (pooled incidence rate ratio 0.43, 95% CI 0.36 to 0.51). Contrary to this, the national survey of paediatric oncology centres found that locks are being used for treatment rather than prevention and that problems related to the formulation of lock solutions currently impede a shift to their prophylactic use in children. (4) Most i.v. treatment days would be saved by early stopping of treatment for children at low risk of infection. The accuracy study was limited primarily by the lack of an adequate reference standard, and the main limitation of the series of systematic reviews was the poor quality of included studies and lack of randomised controlled trials of CVC removal or antimicrobial locks for treatment of infection. There is strong evidence to support the use of antimicrobial locks for prevention of CVC-associated infection; however, few of these studies involved children with cancer. The analysis does not support routine bacterial DNA testing on admission to detect CVC-associated infection, but repeated testing (as a marker of microbial load) should be evaluated in high-risk groups. Further research should determine the effectiveness of antibiotic locks for treating CVC-associated infection. Current Controlled Trials ISRCTN68138140. This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 15, No. 7. See the HTA programme website for further project information.

A Protein Processing Filter Method for Bacterial Identification by Mass Spectrometry-Based Proteomics

A "one-pot" alternative method for processing proteins and isolating peptide mixtures from bacterial samples is presented for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and data reduction. The conventional in-solution digestion of the protein contents of bacteria is compared to a small disposable filter unit placed inside a centrifuge vial for processing and digestion of bacterial proteins. Each processing stage allows filtration of excess reactants and unwanted byproduct while retaining the proteins. Upon addition of trypsin, the peptide mixture solution is passed through the filter while retaining the trypsin enzyme. The peptide mixture is then analyzed by LC-MS/MS with an in-house BACid algorithm for a comparison of the experimental unique peptides to a constructed proteome database of bacterial genus, specie, and strain entries. The concentration of bacteria was varied from 10 × 10(7) to 3.3 × 10(3) cfu/mL for analysis of the effect of concentration on the ability of the sample processing, LC-MS/MS, and data analysis methods to identify bacteria. The protein processing method and dilution procedure result in reliable identification of pure suspensions and mixtures at high and low bacterial concentrations.

Gamma Interferon Produced by Antigen-Specific CD4+T Cells Regulates the Mucosal Immune Responses toCitrobacter rodentiumInfection

Citrobacter rodentium, a murine model pathogen for enteropathogenic Escherichia coli, colonizes the surface of intestinal epithelial cells and causes mucosal inflammation. This bacterium is an ideal model for investigating pathogen-host immune interactions in the gut. It is well known that gene transcripts for Th1 cytokines are highly induced in colonic tissue from mice infected with C. rodentium. However, it remains to be seen whether the Th1 or Th2 cytokines produced by antigen-specific CD4(+) T cells provide effective regulation of the host immune defense against C. rodentium infection. To investigate the antigen-specific immune responses, C. rodentium expressing ovalbumin (OVA-C. rodentium), a model antigen, was generated and used to define antigen-specific responses under gamma interferon (IFN-gamma)-deficient or interleukin-4 (IL-4)-deficient conditions in vivo. The activation of antigen-specific CD4(+) T cells and macrophage phagocytosis were evaluated in the presence of IFN-gamma or IL-4 in vitro. IFN-gamma-deficient mice exhibited a loss of body weight and a higher bacterial concentration in feces during OVA-C. rodentium infection than C57BL/6 (wild type) or IL-4-deficient mice. This occurred through the decreased efficiency of macrophage phagocytosis and the activation of antigen-specific CD4(+) T cells. Furthermore, a deficiency in antigen-specific CD4(+) T-cell-expressed IFN-gamma led to a higher susceptibility to mucosal and gut-derived systemic OVA-C. rodentium infection. These results show that the IFN-gamma produced by antigen-specific CD4(+) T cells plays an important role in the defense against C. rodentium.

Bioaerosols as contributors to poor air quality in Taichung City, Taiwan

Bioaerosols are a type of suspended sediments that contribute to poor air quality in Taiwan. Bioaerosols include allergens such as: fungi, bacteria, actinomycetes, arthropods and protozoa, as well as microbial products such as mycotoxins, endotoxins and glucans. When allergens and microbial products are suspended in the air, local air quality will be influenced adversely. In addition, when the particle size is small enough to pass through the respiratory tract entering the human body, the health of the local population is also threatened. Therefore, the purpose of this study is to attempt to understand the concentration and types of bacteria and the bacteria numbers for various particle size ranges during a study period of June 2005 to February 2006 in Taichung City, Central Taiwan. The results indicate that the total average bacterial concentration by using NA medium incubated for 48 h were 8.0 x 10(2), 1.4 x 10(3), 2.4 x 10(3) and 1.3 x 10(3), 1.9 x 10(3), 3.5 x 10(3) cfu/m(3) for CMES, TRIPS and RFS sampling sites during the daytime and nighttime period of June 2005 to February 2006. Moreover, the total average bacterial concentration by using R(2)A medium incubated for 48 h were 8.5 x 10(2), 1.5 x 10(3), 2.2 x 10(3) and 1.2 x 10(3), 1.7 x 10(3), 2.5 x 10(3) cfu/m(3) for CMES, TRIPS and RFS sampling sites the daytime and nighttime during the same sampling period. The total average bacteria concentration was the same in either NA or R(2)A medium for the same sampling times or sites. The total average bacterial concentration was higher in daytime period than that of nighttime period for CMES, TRIPS and RFS sampling sites. The high average bacterial concentration was found in the particle size range of 0.53-0.71 mm (average bioaerosol size was in the range of 2.1-4.7 microm) for each sampling site. Also, 20 kinds of bacteria exceeded levels for each sampling site and were classified as according to shape: rod, coccus and filamentous.

The role of the RgpA–Kgp proteinase–adhesin complexes in the adherence of Porphyromonas gingivalis to fibroblasts

Porphyromonas gingivalis strains W50 and ATCC 33277 were shown to bind to cultured human fibroblast (MRC-5) cells using flow cytometry. As the concentration of P. gingivalis strain W50 cells was increased relative to the concentration of MRC-5 cells, the number of W50 cells bound per MRC-5 cell increased, as did the percentage of MRC-5 cells with bacteria bound. However, this relationship was only seen for P. gingivalis strain ATCC 33277 at low cell concentrations: at high bacterial cell concentrations strain ATCC 33277 auto-aggregated and binding to the MRC-5 cells decreased. Strain W50 was therefore chosen to study the role of the surface proteinase-adhesin complexes (RgpA-Kgp complexes) in binding to MRC-5 cells. P. gingivalis W50 cells treated with an inhibitor of the RgpA-Kgp complexes exhibited reduced binding to MRC-5 cells. The purified active and proteinase-inactive RgpA-Kgp complexes competitively inhibited binding of W50 to MRC-5 cells, and isogenic mutants of W50 lacking RgpA/B and Kgp displayed reduced binding. P. gingivalis W50 mutant cells lacking Kgp exhibited the lowest binding to MRC-5 cells, suggesting an important role for this proteinase and its associated adhesins in binding to fibroblasts.

Rapid Estimation of Bacteria by a Fluorescent Gold Nanoparticle−Polythiophene Composite

Herein we present a facile method for rapid quantitation of bacterial cells over several logarithmic dilutions. The quantitation is based on loss of the fluorescence intensity of a positively charged Au nanoparticle-polythiophene composite in the presence of bacterial cells. The present method allowed estimation of both Gram-positive and Gram-negative bacteria with cells as low as 1000. Transmission electron microscopic investigations revealed attachment of the composite with bacteria with no discernible change in the morphology of the cells. Further, dynamic light scattering experiments indicated preferential attachment of smaller composite particles over larger ones, which were also attached at higher bacterial concentrations. The ease of operation with minimal sample manipulation steps, high sensitivity, quantitative detection, and its generality offer specific advantages over conventional methods.

Bacillus subtilis Bacteria Hinder the Oxidation and Hydrolysis of Fe2+ Ions

Bacteria are known to associate closely with secondary iron oxides in natural environments, but it is still unclear whether they catalyze their precipitation. Here, Fe2+ ions were progressively added to various concentrations of Bacillus subtilis bacteria in permanently oxic conditions while maintaining the pH at 6.5 by adding a NaOH solution at a monitored rate. The iron/ bacteria precipitates were characterized by wet chemistry, SEM, and XRD. Abiotic syntheses produced nanolepidocrocite, and their kinetics displayed a strong autocatalytic effect. Biotic syntheses led to the formation of tiny and poorly crystallized particles at intermediate bacterial concentrations and to a complete inhibition of particle formation at high bacterial concentrations. The occurrence of the autocatalytic effect was delayed and its intensity was reduced. Both the oxidation and the hydrolysis of Fe2+ ions were hindered.

The Study of Ambient Air Bioaerosols During Summer Daytime and Nighttime Periods in Taichung, Central Taiwan

Suspended particles, of which bioaerosols are one type, constitute one of the main reasons for poor air quality in Taiwan. Bioaerosols include allergens such as fungi, bacteria, actinomycetes, arthropods, and protozoa, as well as microbial products such as mycotoxins, endotoxins, and glucans. When allergens and microbial products are suspended in the air, local air quality will be influenced severely. When the particle size is small enough to pass through the respiratory tract entering the human body, the health of the local population is threatened. Therefore, the purpose of this study was to understand the concentration and types of bacteria during the summer period at four sampling sites in Taichung, central Taiwan. The total average bacterial concentrations at 48-h incubation time during the summer daytime period were 8.1 × 102, 1.9 × 103, 3.7 × 10 3, and 1.1 × 103 cfu/m3 and nighttime period were 1.1 × 103, 2.6 × 103, 3.2 × 103, and 1.9 × 103 cfu/m3 from June 30 to August 1, 2005. The average bacterial concentration increased as the incubated time increased for each particle size range. The high average bacterial concentration was found in the particle size 0.34–0.71 mm (average bioaerosol size was in the range of 1.1–4.7 μm) for each sampling site. There were more than 20 types of bacteria at each sampling site and the bacteria shapes were rod, coccus, and filamentous.

Microbial community diversity and heterotrophic production in a coastal Arctic ecosystem: A stamukhi lake and its source waters

Stamukhi lakes are vast but little‐explored Arctic ecosystems. They occur throughout winter, spring, and early summer near large river inflows along the Arctic coastline, and are the result of freshwater retention behind the thick barrier of rubble ice (stamukhi) that forms at the outer limit of land‐fast sea ice. We examined the molecular biodiversity within all three microbial domains (Bacteria, Archaea, and Eukaryota) and the heterotrophic productivity in Lake Mackenzie, a stamukhi lake in the western Canadian Arctic, and made comparative measurements in the freshwater (Mackenzie River) and marine (Beaufort Sea) source waters. Bacterial and eukaryotic communities in the stamukhi lake differed in composition and diversity from both marine and riverine environments, whereas the archaeal communities were similar in the lake and river. Bacteria 16S ribosomal RNA sequences from the lake were mostly within freshwater clusters of Betaproteobacteria and Bacteroidetes and the Archaea were within the Lake Dagow sediment and Rice cluster‐V clusters of Euryarchaeota. The eukaryotes were mainly ciliates from the subclass Choreotrichia, and there was a notable lack of flagellates. Heterotrophic production rates in the lake were lower than in the river and more similar to those in the sea, despite much higher bacterial concentrations than in either. The lake samples had markedly higher ratios of 3H leucine to 3H thymidine incorporation than in the river and sea, implying some physiological stress. Lake Mackenzie is an active microbial ecosystem with distinct physical and microbiological properties. This circumpolar ecosystem type, vulnerable to the ongoing effects of climate change, likely plays a key functional role in processing riverine inputs to the Arctic Ocean.

UV Disinfection of Dry Weather Creek Flow to Buccaneer Beach

UV Disinfection of Dry Weather Creek Flow to Buccaneer BeachLoma Alta Creek in Oceanside, CA flows to Buccaneer Beach, and the creek's historical high bacterial concentrations have led to regular beach postings during the summer. To avoid beach closures and to achieve the low organism counts required by the State for public health protection, a filtration and UV disinfection system is being implemented to treat the creek's dry weather flows prior to beach...Author(s)Kristin SearcyAndrew SalvesonKeith BourgeousHarold WrightSourceProceedings of the Water Environment FederationSubjectSession 115: UV Efficiency, Effectiveness and ApplicationsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2007ISSN1938-6478SICI1938-6478(20071001)2007:8L.9018;1-DOI10.2175/193864707787781016Volume / Issue2007 / 8Content sourceWEFTECFirst / last page(s)9018 - 9026Copyright2007Word count181Subject keywordsUV DISINFECTIONPUBLIC BEACHCOLLIMATED BEAM DOSE-RESPONSE