Effect of ultraviolet irradiation and chlorination on ampicillin-resistant <Emphasis Type="Italic">Escherichia coli</Emphasis> and its ampicillin resistance gene

Antibiotic resistance is a serious public health risk that may spread via potable and reclaimed water. Effective disinfection is important for inactivation of antibiotic-resistant bacteria and disruption of antibiotic resistance genes. Ampicillin is a widely prescribed antibiotic but its effectiveness is increasingly undermined by resistance. In this study, changes in ampicillin resistance for Escherichia coli (E. coli) CGMCC 1.1595 were analyzed after exposure to different doses of ultraviolet (UV) or chlorine, and damage incurred by the plasmid encoding ampicillin resistance gene bla _TEM-1 was assessed. We reported a greater stability in ampicillinresistant E. coli CGMCC 1.1595 after UV irradiation or chlorination when compared with previously published data for other E. coli strains. UV irradiation and chlorination led to a shift in the mortality frequency distributions of ampicillin-resistant E. coli when subsequently exposed to ampicillin. The ampicillin hemiinhibitory concentration (IC₅₀) without disinfection was 3800 mg·L^–1, and an increment was observed after UV irradiation or chlorination. The IC₅₀ of ampicillin-resistant E. coli was 1.5-fold higher at a UV dose of 40 mJ·cm^–2, and was 1.4-fold higher when exposed to 2.0 mg·L^–1 chlorine. These results indicate that UV irradiation and chlorination can potentially increase the risk of selection for E. coli strains with high ampicillin resistance. There was no evident damage to bla _TEM-1 after 1–10 mg Cl₂·L^–1 chlorination, while a UV dose of 80 mJ·cm^–2 yielded a damage ratio for bla _TEM-1 of approximately 1.2-log. Therefore, high UV doses are required for effective disruption of antibiotic resistance genes in bacteria.     

Simulation tools to support bathing water quality management: Escherichia coli bacteria in a Baltic lagoon

Insufficient hygienic water quality and bathing prohibitions are still a serious problem in the Szczecin Lagoon (southern Baltic). In our study we focus on the southern lagoon coast and analyse the causes and consequences of high Escherichia coli bacteria concentrations. For this purpose we carry out laboratory experiments on the behaviour of E.coli in the lagoon, a literature review and apply a three-dimensional flow model together with a Lagrangian particle tracking routine. Three major E.coli sources, the Uecker river, the wetlands with cattle as well as sea gulls with bathing and fisheries were allocated, quantified and compiled into an emission scenario. This serves as input for transport simulations under different wind conditions and for the development of a spatial contamination map. Reasons for high E.coli concentrations in the lagoon are a permanent supply from different sources and the special environmental situation in the lagoon. The availability of organic matter, either in form of reed stems or as muddy sediments, has a positive effect on bacteria survival. Very important, too, are the prevailing wind and flow conditions, which cause water and organism transport in narrow ribbons along the coastline and promote near-shore accumulations. Even in our shallow lagoon, the application of a 3D-model is beneficial. Heavy rains are, very likely, responsible for the outstanding high total-coliform concentrations of 11,000?cfu/100?ml on August 21, 2006. The model system proved to be a valuable tool for spatial analysis and is suitable to support the development of bathing water profiles according to the EU Bathing Water Directive (2006/7/EC).     

New methodological strategies for detecting bacterial indicators

The development of monitoring strategies for the early warning of seawater pollution, with particular reference to faecal and hydrocarbon contamination, has been the specific goal of research carried out within the Cluster 10-SAM (Advanced Systems for Coastal Marine Monitoring) Project, funded by the Italian Ministry for University and Scientific Research. Advanced analytical approaches have been designed and applied to detect bacterial species that have been selected as potential indicators of pollution in seawater samples. We report the results obtained using the fluorescent antibody and enzymatic assays for the detection of Escherichia coli, and a real-time PCR protocol for monitoring marine areas for hydrocarbon pollution. Immunofluorescence and enzymatic methods revealed the occurrence of different faecal pollution levels, reaching 10⁵ E. coli cells 100 ml^?1 in the Straits of Messina. Real-time PCR results corresponded to the different degree of oil pollution of the analysed samples. The specificity and speed make these methods promising for the detection and evaluation of marine pollution.     

Effect of streambed bacteria release on E. coli concentrations: Monitoring and modeling with the modified SWAT

Streambed sediment has been attracting attention as a reservoir for bacteria, including pathogenic strains. Soil and Water Assessment Tool (SWAT) has been augmented with a bacteria transport subroutine in SWAT2005 in which bacteria die-off is the only in-stream process. The purpose of this study was to develop the partial model of sediment-associated bacteria transport in stream and to evaluate the potential significance of streambed Escherichia coli (E. coli) release and deposition within the SWAT microbial water quality simulations. Streambed E. coli release and deposition were simulated based on the sediment resuspension and deposition modules in SWAT. The modified SWAT was applied to the Little Cove Creek watershed, Pennsylvania, which has forestry and dairy pasture landuses. Temporal changes in sediment E. coli concentrations were derived from monitoring data rather than from a streambed bacteria population model. Sensitivity analyses and calibrations were separately conducted for both hydrologic and bacteria parameters. Hydrologic calibration characterized soils in the watershed as pervious and thus the surface runoff was only moderately contributing to the streamflow. However, the surface runoff carried large numbers of E. coli to the stream, and sediment resuspension contributed to the persistent concentration of E. coli in stream water. Although the uncertainty of E. coli concentrations in streambed sediments and from wildlife probably affected the performance of the modified SWAT model, this study qualitatively confirmed the significance of modeling E. coli release from streambed and deposition for the SWAT microbial water quality simulations. Further developments should include modeling dynamics of bacteria populations within streambeds.     

Mikrobielle Sanierung von 2,4,6-Trinitrotoluol (TNT) kontaminierten Böden

Within the limits of a feasability study abouton-site bioremediation methods for TNT-contaminated soils, composting was chosen as a very promising and cheap method. This method was critically compared with those described in the literature and was primarily rated under ecotoxicological aspects. The investigated location is the former munition plant «Tanne» in the aerea of Clausthal-Zellerfeld in Lower Saxony, Germany. To estimate the autochtonic microflora, we assessed the number of aerobic heterotrophic bacteria and determined their respiration activity in soils. In addition, we isolated bacteria and examined their capacity to metabolize TNTin vitro. Both the amount of autochtonic microrganisms (4.7×10⁸ to 1.2×10¹⁰ colony forming units (cfu)/kg dryweight) as well as their respiration activity did not correlate with the concentrations of nitrotoluenes in the soils. With high contaminated soil (20 g TNT/kg dry weight) we carried out a small compost in the range of 10 liters. During 28 days of composting TNT-concentration decrease over 90% and only minor amounts of monoaminodinitrotoluenes were generated. However, an acidic pretreatment of the compost material at the end of the reaction showed that TNT could be partially resolved under these extreme conditions and that an ecotoxicological risk may still exist. Possible changes in the realization of the composting process in order to make sure that the contaminants are savely bound to the humin matrix are discussed.     

Flow cytometric assessment of the effects of chlorine,chloramine, and UV on bacteria by using nucleic acid stains and 5-cyano-2,3-ditolyltetrazolium chloride

Flow cytometry (FCM) has been widely used in multi-parametric assessment of cells in various research fields, especially in environmental sciences. This study detected the metabolic activity of Escherichia coli and Staphylococcus aureus by using an FCM method based on 5-cyano-2,3-ditolyltetrazolium chloride (CTC); the accuracy of this method was enhanced by adding SYTO 9 and 10%R2A broth. The disinfection effects of chlorine, chloramine, and UV were subsequently evaluated by FCM methods. Chlorine demonstrated stronger and faster destructive effects on cytomembrane than chloramine, and nucleic acids decomposed afterwards. The metabolic activity of the bacteria persisted after the cytomembranewas damaged as detected using CTC. Low-pressure (LP) UV or medium-pressure (MP) UV treatments exerted no significant effects on membrane permeability. The metabolic activity of the bacteria decreased with increasing UV dosage, and MP-UV was a stronger inhibitor of metabolic activity than LP-UV. Furthermore, the membrane of Gram-positive S. aureus was more resistant to chlorine/chloramine than that of Gram-negative E. coli. In addition, S. aureus showed higher resistance to UV irradiation than E. coli.

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莱州湾近岸海域中典型抗生素与抗性细菌分布特征及其内在相关性

为了揭示海陆衔接区环境中抗生素与抗性细菌分布特征及其内在相关性,以莱州湾及其主要入海河流为研究区域,利用HPLC-MS/MS分析样品中15种磺胺类抗生素(SAs)和6种喹诺酮类抗生素(QNs)的浓度,并通过改良的Method 1604(US EPA)评估海水与沉积物中2种典型水传病原微生物大肠杆菌(E.coli)与金黄色葡萄球菌(S.aureus)的抗生素抗性水平,进而探讨该区域水体中抗性菌株的分布特点以及微生物抗性率与相应抗生素浓度的相关性。结果显示,莱州湾水体与沉积物中普遍存在磺胺与喹诺酮类抗生素残留及抗性污染问题。两大类抗生素在水体中平均残留浓度分别为3.89 ng·L~(-1)(SAs)和234.68ng·L~(-1)(QNs),在沉积物中分别为0.91 ng·g~(-1)(SAs)和49.37 ng·g~(-1)(QNs),且分布特征基本呈现自河流向海洋逐渐递减的趋势,说明河流输入是莱州湾抗生素污染的主要来源。在水体中,具有磺胺类抗性的E.coli和S.aureus平均检出量分别达到2 018和4 683 CFU·L~(-1),抗性率范围分别在0%~37.3%和10.6%~45.8%之间;而2种喹诺酮类抗性病原微生物的平均检出量则相对较低,分别为1 315 CFU·L~(-1)(E.coli)和1 461 CFU·L~(-1)(S.aureus),抗性率分别为0%~50.0%和0%~20.8%;此外,相比于E.coli,S.aureus为沉积物中的主要抗性病原微生物,磺胺与喹诺酮类抗性S.aureus检出率均高于80%,平均检出量分别为24CFU·g~(-1)和18 CFU·g~(-1)。相关性分析表明,莱州湾近岸海域水体中磺胺类抗生素浓度与磺胺类抗性微生物总量之间具有良好的线性关系,然而其与微生物抗性率之间并未表现出相似的规律,说明近岸海洋环境中抗生素的残留量不是影响抗性菌株丰度的唯一因素。     

零价纳米铁对大肠杆菌的毒性效应

以大肠杆菌为研究对象,通过检测尺寸为20 nm的零价纳米铁暴露下大肠杆菌形貌、生长曲线和细胞内酶活性的变化,研究了零价纳米铁对大肠杆菌的毒性效应,并探讨了其可能的毒性机制.用透射电镜(TEM)观察零价纳米铁与大肠杆菌(JM109)接触后细胞的形态变化;用0、112、560和1 120 mg·L-1的零价纳米铁染毒大肠杆...     

Mineralogical variables that control the antibacterial effectiveness of a natural clay deposit

As antibiotic-resistant bacterial strains emerge and pose increased global health risks, new antibacterial agents are needed as alternatives to conventional antimicrobials. Naturally occurring antibacterial clays have been identified which are effective in killing antibiotic-resistant bacteria. This study examines a hydrothermally formed antibacterial clay deposit near Crater Lake, OR (USA). Our hypothesis is that antibacterial clays buffer pH and Eh conditions to dissolve unstable mineral phases containing transition metals (primarily Fe²⁺), while smectite interlayers serve as reservoirs for time release of bactericidal components. Model pathogens (Escherichia coli ATCC 25922 and Staphylococcus epidermidis ATCC 14990) were incubated with clays from different alteration zones of the hydrothermal deposit. In vitro antibacterial susceptibility testing showed that reduced mineral zones were bactericidal, while more oxidized zones had variable antibacterial effect. TEM images showed no indication of cell lysis. Cytoplasmic condensation and cell wall accumulations of <100 nm particles were seen within both bacterial populations. Electron energy loss analysis indicates precipitation of intracellular Fe³⁺-oxide nanoparticles (<10 nm) in E. coli after 24 h. Clay minerals and pyrite buffer aqueous solutions to pH 2.5–3.1, Eh > 630 mV and contain elevated level (mM) of soluble Fe (Fe²⁺ and Fe³⁺) and Al³⁺. Our interpretation is that rapid uptake of Fe²⁺ impairs bacterial metabolism by flooding the cell with excess Fe²⁺ and overwhelming iron storage proteins. As the intracellular Fe²⁺ oxidizes, it produces reactive oxygen species that damage biomolecules and precipitates Fe-oxides. The ability of antibacterial clays to buffer pH and Eh in chronic non-healing wounds to conditions of healthy skin appears key to their healing potential and viability as an alternative to conventional antibiotics.     

Mikrobiologische Volatilisierung von anorganischem Selen aus Deponiesickerwässern bei umweltrelevanten Konzentrationen

Background, aim, and scope Determination of the rates of microbial alkylation are of interest with respect to natural attenuation of harmful selenium concentrations or selenium charges in contaminated ecosystems. Materials and methods Landfill gas and the headspace of microbial microcosm incubation vessels were sampled in Tedlar^® bags. On-line hyphenation of an efficient enrichment method (cryotrapping-cryofocusing), a gaschromatographic separation technique, and the sensitive ICP-MS detection system was used for speciation of volatile organoselenium compounds. A detection limit at the ultra trace level (pg Se) was achieved with this CT-CF-GC-ICP-MS technique. Results Incubation of landfill leachate with Alternata alternata as an active methylating organism showed a production of volatile selenium compounds (DMSe, DMDSe, EMDSe, DEDSe) over the whole range of applied inorganic selenium concentrations (10?µg?L^–1 to 10?mg?L^–1), with volatilization rates of up to 10?mg m^–3?d^–1. For selenium concentrations of 1?mg?L^–1 in the nutrient broth, up to 7?% of the inorganic selenium was volatilized after one week. The same volatile selenium compounds were observed in landfill gas. Discussion The amount of volatilized selenium was comparable to that found in other studies with microbial pure cultures as well as isolates from waters or soils, but at much lower initial concentrations used in the incubations. Conclusions The alkylation of selenium in the enriched mixed culture from landfill leachate at environmentally relevant concentrations indicates that the organoselenium compounds of same species composition and distribution determined in landfill gas are produced by microorganisms. Recommendations and perspectives The microbial alkylation of toxic inorganic selenium species to less toxic or non-toxic, volatile compounds is an efficient method for bioremediation of contaminated sites even at relatively low Se concentrations.     

COLIWAVE a simulation model for survival of E. coli O157:H7 in dairy manure and manure-amended soil

A simulation model was developed to investigate the relative effects of temperature, oxygen concentration, substrate content and competition by autochthonous microbial community on the oscillatory behaviour and survival of Escherichia coli O157:H7 in manure and manure-amended soil. The overall decline in E. coli O157:H7 was primarily determined by competition with autochthonous copiotrophic bacteria simulated by an inter-specific competition term according to Lotka-Volterra. Oscillations of bacterial populations were attained by the relationships between relative growth and death rates with readily available substrate content. The model contains a logistic and exponential relation of relative growth and death rates, respectively, of E. coli O157:H7 and copiotrophic bacteria with temperature, resulting in optimum curves for net growth rates similar to the curves reported in the literature. The model has been both calibrated and validated on experimental data. The model was used to perform sensitivity analysis and to evaluate different manure and soil management scenarios in terms of survival of E. coli O157:H7. The relative effects of changes in temperature on simulated survival time of E. coli O157:H7 were more pronounced than changes in oxygen condition. Testing manure storage scenarios with realistic data revealed that manure stored in a heap that was turned every week resulted in almost 70% reduction of E. coli O157:H7 survival compared to unturned manure. At the surface of a heap with unturned manure, simulated survival time was the longest (2.4 times longer than inside the same heap). The simulation model provides a new approach to investigating dynamic changes of invasive microorganisms in natural substrates such as manure or manure-amended soil.     

快速评估近岸海洋水体与沉积物中E.coli与S.aureus抗生素抗性水平的新方法

随着抗生素抗性污染日益严重,快速评估环境中典型病原菌与条件性致病菌的抗生素抗性水平,对掌握区域环境抗生素抗性污染状况、揭示抗性污染传播规律至关重要。通过以最低抑菌浓度浸入抗生素改进MI、VJ培养基,并结合滤膜法,建立了针对近岸海洋环境中指示性病原微生物大肠杆菌(Escherichia coli,E.coli)与金黄色葡萄球菌(Staphylococcus aureus,S.aureus)的抗生素抗性监测方法。水体和沉积物样品抗生素抗性水平评估实验结果显示,该方法具有较好重现性(水体和沉积物中E.coli和S.aureus抗生素抗性水平的相对标准偏差分别为11%、8%)与准确度(水体和沉积物中E.coli和S.aureus的平均回收率分别为83.5%、68.4%;相对于CLSI药敏试验的偏离度为±0.1)。且与CLSI药敏实验相比,该方法过程简便、耗时短(36 h/84 h),能最大限度节约经济和人员成本提高抗性评价效率。应用该方法评估辽河口与莱州湾环境中2种病原微生物磺胺类抗生素抗性水平,结果显示辽河口水体中E.coli和S.aureus磺胺二甲嘧啶的平均抗性率分别为27.0%、28.4%,沉积物中分别为35.5%、34.6%;莱州湾水体中E.coli和S.aureus磺胺二甲嘧啶的平均抗性率分别为26.0%、14.5%,沉积物中分别为12.0%、32.9%。该方法适用于河口、近岸海洋及入海排污口水体与沉积物样品中E.coli与S.aureus的快速分析及抗生素抗性水平评估。     

纳米银与银离子对土壤微生物及酶活性的影响

为研究纳米银和银离子对土壤微生物的影响,采用土壤培养方式,对不同剂量纳米银(10、50、100 mg·kg~(-1))和银离子(1、5、10 mg·kg~(-1))暴露下黄褐土、砖红壤中可培养微生物数量及土壤酶活性(脲酶、荧光素二乙酸酯水解酶、蔗糖酶、过氧化氢酶)进行研究,并采用纯培养方法对纳米银和银离子暴露下的大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)凋亡情况进行检测,对纳米银释放的银离子毒性进行评估。结果表明,随着纳米银剂量的增加,土壤可培养微生物数量显著减少,脲酶和过氧化氢酶活性降低,蔗糖酶、荧光素二乙酸酯水解酶(FDA酶)活性没有显著变化;银离子处理中微生物数量明显减少,但土壤酶活性被激活。10 mg·L~(-1)纳米银暴露1 h后大肠杆菌、金黄色葡萄球菌凋亡率、死亡率增高;随着培养时间的延长,纳米银缓慢释放银离子,并促进大肠杆菌的凋亡。综上分析,纳米银能够抑制土壤可培养微生物生长和酶活性,其中脲酶、过氧化氢酶对纳米银较为敏感,蔗糖酶、FDA酶受纳米银的影响较小;纳米银的毒性一方面是其本身的特异抗菌性,也有部分来自缓慢释放的银离子。     

Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study of Acartia, Temora and Eurytemora species in the south-west Baltic

Information on physiological rates and tolerances helps one gain a cause-and-effect understanding of the role that some environmental (bottom–up) factors play in regulating the seasonality and productivity of key species. We combined the results of laboratory experiments on reproductive success and field time series data on adult abundance to explore factors controlling the seasonality of Acartia spp., Eurytemora affinis and Temora longicornis, key copepods of brackish, coastal and temperate environments. Patterns in laboratory and field data were discussed using a metabolic framework that included the effects of ‘controlling’, ‘masking’ and ‘directive’ environmental factors. Over a 5-year period, changes in adult abundance within two south-west Baltic field sites (Kiel Fjord Pier, 54°19′89N, 10°09′06E, 12–21 psu, and North/Baltic Sea Canal NOK, 54°20′45N, 9°57′02E, 4–10 psu) were evaluated with respect to changes in temperature, salinity, day length and chlorophyll a concentration. Acartia spp. dominated the copepod assemblage at both sites (up to 16,764 and 21,771 females m^?3 at NOK and Pier) and was 4 to 10 times more abundant than E. affinis (to 2,939?m^?3 at NOK) and T. longicornis (to 1,959?m^?3 at Pier), respectively. Species-specific salinity tolerance explains differences in adult abundance between sampling sites whereas phenological differences among species are best explained by the influence of species-specific thermal windows and prey requirements supporting survival and egg production. Multiple intrinsic and extrinsic (environmental) factors influence the production of different egg types (normal and resting), regulate life-history strategies and influence match–mismatch dynamics.     

New hydroepidemiological models of indicator organisms and zoonotic pathogens in agricultural watersheds

Simple analytical models are derived to assess how a series of cattle animal farms affect the transport and fate of an indicator organism (Escherichia coli) and a zoonotic pathogen (Campylobacter) in a stream. Separate steady-state mass-balance models are developed and solved for the ultimate minimum and maximum concentrations for the two organisms. The E. coli model assumes that the organism is ubiquitous and abundant in the animals’ digestive tracts. In contrast, a simple dose-response model is employed to relate the Campylobacter prevalence to drinking water drawn from the stream. Because faecal indicators are commonly employed to assess the efficacy of best management practice (BMP) interventions, we also employ the models to assess how BMPs impact pathogen levels. The model provides predictions of (a) the relative removal efficacy for Campylobacter and (b) the prevalence of Campylobacter infection among farm animals after implementation of BMPs. Dimensionless numbers and simple graphs are developed to assess how prevalence is influenced by a number of factors including animal density and farm spacing. A significant outcome of this model development is that the numerous dimensional input and parameter variables are reduced to a group of just four dimensionless Campylobacter-related quantities, characterizing: animal density; in-stream attenuation; animal-to-animal transmission; and infection recovery. Calculations reveal that for some constellations of these four quantities there can be a greater-than-expected benefit in that the proportional reduction of stream Campylobacter concentrations post-BMP can substantially exceed the proportional reduction of concentrations of E. coli in that stream. In addition, a criterion for system sterility (i.e., the conditions required for the farm infection rate to decrease with downstream distance) is derived.     

Titanium dioxide nanoparticles induce bacterial membrane rupture by reactive oxygen species generation

Nano-titania is widely used in the food industry due to its efficient antimicrobial activity. However, the mechanism of microbial toxicity of nano-titania is poorly known. Here, nano-TiO₂ has been fabricated by microwave-irradiation chemistry, a new method, and then tested for antimicrobial activity. Mutagenicity of nano-TiO₂ was evaluated using Salmonella typhimurium histidine-auxotrophic strains. The reactive oxygen generation test was performed using 2,7-dichlorofluorescein diacetate dye. To test membrane permeabilization, E. coli cultures were grown in nutrient broth at an optical density of 0.3–0.5 at 610 nm, harvested by centrifugation at 11,000g for 10 min, washed and resuspended in 0.5 % NaCl solution. We also analyzed superoxide formation and membrane integrity, and we used scanning electron microscopy. Results show that nano-TiO₂ has a minimum inhibitory concentration of 15 µg/mL, and a minimum bactericidal concentration of 20 µg/mL for E. coli. The bacterial inner wall was ruptured, and cytoplasmic content was released after 5 min of treatment in a dose-dependent manner. Notably, superoxide formation was not observed, which establishes the fact that reactive oxygen generation and alteration of membrane integrity, as well as permeability, is the major mechanism of antimicrobial activity of nano-TiO₂.     

New beach in a shallow estuarine lagoon: a model-based <Emphasis Type="Italic">E. coli</Emphasis> pollution risk assessment

A 3D hydrodynamic model has been applied to the Curonian Lagoon to study the pollution impact of E. coli on a new beach that might be opened in the lagoon. Through a field survey the E. coli inputs were measured and then used in the numerical model, and through laboratory experiments the decay rate of E. coli was established. The model has been calibrated and validated for the year 2015, and several scenarios have been studied, such as sewage system breakdown, severe weather conditions or high river loads. The model has then been run for a period of 12 years to obtain a robust statistics for the pollution on the planned beach. Results show that the decay rate of E. coli is between 0.55 days and 2.3 days and the modeled decay times are compatible with these numbers. The only scenario that would create a risk for the bathing waters of the beach is a breakdown of the sewage system on the Curonian Spit. In this case the hours (and days) over legally allowable bathing threshold were computed in order to estimate the number of days the beach could be closed. These results have been confirmed by the 12 year simulations. With an influence map analysis the two most critical sewage systems could be identified.     

Early murine immune responses from endotracheal exposures to biotechnology-related Bacillus strains

An immunology-based in vivo screening regime was used to assess the potential pathogenicity of biotechnology-related microbes. Strains of Bacillus cereus (Bc), Bacillus subtilis (Bs), Bacillus thuringiensis (Bt), and Bt commercial products (CPs) were tested. Balb/c mice were endotracheally instilled with purified spores, diluted CP, or vegetative cells (VC) (live or dead). Exposed mice were evaluated for changes in behavioral and physical symptoms, bacterial clearance, pulmonary granulocytes, and pulmonary and circulatory pyrogenic cytokines (interleukins (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α), as well as acute phase biomarkers (fibrinogen and serum amyloid A). Except for some differences in clearance rates, no marked effects were observed in mice exposed to any spore at 10⁶ or 10⁷ colony forming units (cfu). In contrast, live Bc or Bt VCs (10⁵ or 10⁶?cfu) produced shock-like symptoms (lethargy, hunched appearance, ruffled fur, and respiratory distress), and 11–200-fold elevations in pyrogenic cytokines at 2-h post-exposure. In the study, 4-h effects included increased lethargy, ocular discharge, and 1.5–4-fold rise in circulatory acute phase markers, but no indications of recovery. Bs VC did not produce any changes in symptoms or biomarkers. After 2 or 4?h of exposure to dead VC, increases of only plasma IL-1β and TNF-α (4.6- and 12.4-fold, respectively) were observed. These findings demonstrate that purified spores produced no marked effects in mice compared to that of metabolically active bacteria. This early screening regime was successful in distinguishing the pathogenicity of the different Bacillus species, and might be useful for assessing the relative hazard potential of other biotechnology-related candidate strains.     

A natural history study of Encope grandis and Mellita grantii,two sand dollars in the northern gulf of California,Mexico

Populations of the sand dollars Encope grandis and Mellita grantii were studied at Playa Hermosa in the northern Gulf of California, Mexico. Intertidal distribution and abundance were estimated for the two species from 1969 to 1972. They occurred in the lower intertidal (-0.4 to -1.3 m) and on into the subtidal. Density of E. grandis varied from a high of 380/m² in the spring of 1970 to a low of 0.1/m² in the fall of 1971. Density of M. grantii ranged from a high of 56/m² in 1970 to a low of 0.8/m² in 1971. Growth curves were constructed based on shifts in the modes of the size distributions, and rates of mortality were estimated from the growth parameters and size distributions. It is estimated that E. grandis would attain 95% of its maximum size (74 mm) in about 6 years with an annual mortality rate of 18%. M. grantii would reach 95% of its maximum size (38 mm) in about 5 years with an annual mortality rate of 58%. The populations of these sand dollars appear to be limited by the physical environment.     

Effect of electronic waste on E. coli genomic integrity: a possible role for metal induced carcinogenesis

Electronic waste (e-waste) poses a major public health threat for developing countries’ populations. The hazards of e-waste are exacerbated by crude recycling methods. In this study, the presence of metals in e-waste samples obtained from Lagos, Nigeria, was assessed using atomic absorption spectrometry. The effect of e-waste on Escherichia coli (E. coli) PQ-37 genomic integrity was evaluated using the SOS chromotest. The means of metal concentrations in the evaluated samples were 16 (cadmium), 7.3 (nickel), 11 (chromium), 20 (lead), 3100 (iron), 90 (zinc), and 2000 (copper) μg_L^?1. Damage to E. coli deoxyribonucleic acid (DNA) increased proportionally to the metal concentrations. Significant amounts of DNA damaging agents from inadequately processed e-waste are present in the studied environment, which will have implications for adverse effects on public and ecological health. Existing policies against dumping of toxic materials in susceptible communities should be enforced.