Molecular profiling of indoor microbial communities in moisture damaged and non-damaged buildings

Epidemiological studies have shown an elevation in the incidence of asthma, allergic symptoms and respiratory infections among people living or working in buildings with moisture and mould problems. Microbial growth is suspected to have a key role, since the severity of microbial contamination and symptoms show a positive correlation, while the removal of contaminated materials relieves the symptoms. However, the cause-and-effect relationship has not been well established and knowledge of the causative agents is incomplete. The present consensus of indoor microbes relies on culture-based methods. Microbial cultivation and identification is known to provide qualitatively and quantitatively biased results, which is suspected to be one of the reasons behind the often inconsistent findings between objectively measured microbiological attributes and health. In the present study the indoor microbial communities were assessed using culture-independent, DNA based methods. Fungal and bacterial diversity was determined by amplifying and sequencing the nucITS- and16S-gene regions, correspondingly. In addition, the cell equivalent numbers of 69 mould species or groups were determined by quantitative PCR (qPCR). The results from molecular analyses were compared with results obtained using traditional plate cultivation for fungi. Using DNA-based tools, the indoor microbial diversity was found to be consistently higher and taxonomically wider than viable diversity. The dominant sequence types of fungi, and also of bacteria were mainly affiliated with well-known microbial species. However, in each building they were accompanied by various rare, uncultivable and unknown species. In both moisture-damaged and undamaged buildings the dominant fungal sequence phylotypes were affiliated with the classes Dothideomycetes (mould-like filamentous ascomycetes); Agaricomycetes (mushroom- and polypore-like filamentous basidiomycetes); Urediniomycetes (rust-like basidiomycetes); Tremellomycetes and the family Malasseziales (both yeast-like basidiomycetes). The most probable source for the majority of fungal types was the outdoor environment. In contrast, the dominant bacterial phylotypes in both damaged and undamaged buildings were affiliated with human-associated members within the phyla Actinobacteria and Firmicutes. Indications of elevated fungal diversity within potentially moisture-damage-associated fungal groups were recorded in two of the damaged buildings, while one of the buildings was characterized by an abundance of members of the Penicillium chrysogenum and P. commune species complexes. However, due to the small sample number and strong normal variation firm conclusions concerning the effect of moisture damage on the species diversity could not be made. The fungal communities in dust samples showed seasonal variation, which reflected the seasonal fluctuation of outdoor fungi. Seasonal variation of bacterial communities was less clear but to some extent attributable to the outdoor sources as well. The comparison of methods showed that clone library sequencing was a feasible method for describing the total microbial diversity, indicated a moderate quantitative correlation between sequencing and qPCR results and confirmed that culture based methods give both a qualitative and quantitative underestimate of microbial diversity in the indoor environment. However, certain important indoor fungi such as Penicillium spp. were clearly underrepresented in the sequence material, probably due to their physiological and genetic properties. Species specific qPCR was a more efficient and sensitive method for detecting and quantitating individual species than sequencing, but in order to exploit the full advantage of the method in building investigations more information is needed about the microbial species growing on damaged materials. In the present study, a new method was also developed for enhanced screening of the marker gene clone libraries. The suitability of the screening method to different kinds of microbial environments including biowaste compost material and indoor settled dusts was evaluated. The usability was found to be restricted to environments that support the growth and subsequent dominance of a small number microbial species, such as compost material.

Suolistopatogeenisten Escherichia coli -bakteerien esiintyvyys ripulipotilailla ja raa’oissa lihatuotteissa Burkina Fasossa sekä enterohemorraagisten E. coli -kantojen karakterisointi

Suolistopatogeeniset Escherichia coli -bakteerit eli ripulikolit aiheuttavat ihmisellä suolistoinfektioita. Kuten normaalimikrobiston E. coli -bakteerit, ne esiintyvät ihmisen lisäksi muiden nisäkkäiden, etenkin märehtijöiden, ja lintujen suolistossa. Lisäksi ne voivat esiintyä maaperässä ja vesistöissä. Ihminen voi saada tartunnan eläinperäisten elintarvikkeiden välityksellä tai juomalla eläinten tai ihmisen ulosteilla saastunutta vettä. Ripulikolit voidaan jakaa ainakin viiteen ryhmään perustuen niiden erilaisiin virulenssiominaisuuksiin: enteropatogeeninen E. coli (EPEC), enterotoksigeeninen E. coli (ETEC), enterohemorraaginen E. coli (EHEC), enteroinvasiivinen E. coli (EIEC) ja enteroaggregatiivinen E. coli (EAEC). EPEC aiheuttaa etenkin kehitysmaissa pikkulapsille ripulia. ETEC aiheuttaa turistiripulia ja vastasyntyneiden ripulia kehitysmaissa. EHEC aiheuttaa ripulia tai veriripulia, joka voi varsinkin pienillä lapsilla johtaa hemolyyttis-ureemiseen oireyhtymään (HUS) ja munuaisten vaurioitumiseen. EIEC aiheuttaa Shigellan kaltaista ripulia, joka voi olla veristä. EAEC on yhdistetty lähinnä pitkittyneisiin ripuleihin. Tutkimuksessa selvitettiin suolistopatogeenisten E. coli -bakteerien esiintyvyyttä Burkina Fasossa, josta ei ole saatavilla aikaisempaa tietoa ripulikolien esiintymisestä ihmisissä ja elintarvikkeissa. Ulostenäytteitä otettiin ripulia sairastavilta alle viisivuotiailta lapsilta maaseudulta kahdesta kylästä, Boromosta ja Gourcysta, ja maan pääkaupungista Ouagadougousta (110 näytettä). Lihanäytteitä (kanaa, nautaa, lammasta ja naudan suolta, jota käytetään ihmisravinnoksi) otettiin Ouagadougoun toreilla myytävistä kypsentämättömistä lihoista (120 näytettä). Näytteistä saadut bakteerisekaviljelmät tutkittiin monialukkeisella PCR-menetelmällä, joka tunnistaa viiden ripulikoliryhmän virulenssigeenejä. Lisäksi lihanäytteistä eristettiin 20 EHEC-kantaa shigatoksiinin stx-geenin havaitsemiseen perustuvalla pesäkehybridisaatiolla ja PCR-seulonnalla, ja karakterisoitiin mahdollisten virulenssiominaisuuksien selvittämiseksi. Tutkimus osoitti, että ripulikolien aiheuttamat suolistoinfektiot ovat yleisiä ripulia sairastavilla pikkulapsilla Burkina Fasossa. Ulostenäytteistä 59 % oli positiivisia. Useimmiten lapsilla esiintyi EAEC- (32 %) ETEC- (31 %) ja EPEC-patoryhmiä (20 %). EIEC- (2 %) ja EHEC-patoryhmiä (1 %) esiintyi vähän. Myös useamman patoryhmän sekainfektiot olivat yleisiä (24 %). Eri paikkakuntien välillä oli tilastollisesti merkitseviä eroja ripulikolien esiintymisessä. Gourcyssa ripulikoleja esiintyi useammin kuin Ouagadougoussa ja Boromossa. Tutkimuksessa kävi ilmi, että Ouagadougoun toreilla myytävissä lihoissa on paljon ripulikoleja. Lihanäytteistä 43 % oli positiivisia. Yleisimmin lihoissa esiintyi EHEC (28 %), EPEC (20 %), ETEC (8 %) ja EAEC (5 %). EIEC-ryhmää ei havaittu lihoissa. Myös useamman patoryhmän sekakontaminaatioita löytyi (17 %) lihoista. Ripulikolien esiintyvyydessä eri lihojen välillä ei ollut tilastollisesti merkitseviä eroja, kun tarkasteltiin kaikkia patoryhmiä yhdessä. Eri patoryhmien esiintyvyyttä tarkasteltaessa EHEC-patoryhmää ei esiintynyt ollenkaan kanassa ja ero oli tilastollisesti merkitsevä muihin lihoihin verrattuna. Lihoista eristetyt 20 EHEC-kantaa kuuluivat 14 eri serotyyppiin, joista osa on aikaisemmin eristetty suolistoinfektioihin ja HUSoireyhtymään sairastuneilta ihmisiltä. Kaikki kannat olivat stx1-positiivisia ja puolella oli lisäksi stx2-geeni, jota pidetään shigatoksiinin virulentimpana muotona. Kahdelta EHEC-kannalta löytyi myös ETECpatoryhmän lämpöstabiilin enterotoksiini Ia:n geeni eli kannat olivat kahden patoryhmän välimuotoa ja osoitus geenien siirtymisestä eri patoryhmien välillä. Vaikka nuorimmat näytteen antaneet lapsipotilaat tuskin söivät lihaa, sen voidaan ajatella silti olevan edustava näyte lasten elinympäristöstä, sillä lasten ruoka valmistetaan usein samoissa oloissa, joissa raakaa lihaa käsitellään. Saastunut liha voi siten olla pikkulasten ripulikoli-infektioiden aiheuttaja.

Use of finite wordlength FIR digital filter structures with improved magnitude and phase characteristics for reduction of muscle noise in EEG signals

One of the main disturbances in EEG signals is EMG artefacts generated by muscle movements. In the paper, the use of a linear phase FIR digital low-pass filter with finite wordlength precision coefficients is proposed, designed using the compensation procedure, to minimise EMG artefacts in contaminated EEG signals. To make the filtering more effective, different structures are used, i.e. cascading, twicing and sharpening (apart from simple low-pass filtering) of the designed FIR filter Modifications are proposed to twicing and sharpening structures to regain the linear phase characteristics that are lost in conventional twicing and sharpening operations. The efficacy of all these transformed filters in minimising EMG artefacts is studied, using SNR improvements as a performance measure for simulated signals. Time plots of the signals are also compared. Studies show that the modified sharpening structure is superior in performance to all other proposed methods. These algorithms have also been applied to real or recorded EMG-contaminated EEG signal. Comparison of time plots, and also the output SNR, show that the proposed modified sharpened structure works better in minimising EMG artefacts compared with other methods considered.

Mitigation of Alkali Induced Heave in Rectorite Soil with Fly Ash

Mechanisms that control the volume changes behavior of foundation soils are well understood. The changes that occur in the behavior of soil due to migration of pollutants are not well understood. The extent of changes that occur in the presence of small concentration of contaminants can be predicted based on changes in the thickness of double layer and associated fabric changes. Interactions that occur with strong contaminants depends on the type of soil, type and concentration of contamination and duration of interaction etc It has been shown that different concentrations (1N and 4N) of sodium hydroxide solution causes abnormal changes on volume change behaviour of soil due to mineralogical changes. An attempt is made in this paper to stabilize contaminated soil using fly ash, after establishing its stability in alkali solutions. It was found that the effectiveness of fly ash to control the alkali induced heave increases with fly ash content incorporated into the soil. X-ray diffraction studies reveal that the mineralogical changes that occur in soil due to alkali interaction are inhibited by the presence of fly ash.

Spatial Analysis and Characterisation of Lentic Ecosystems: A Case Study of Varthur Lake, Bangalore

Lentic ecosystems vital functions such as recycling of nutrients, purification of water, recharge of groundwater,augmenting and maintenance of stream flow and habitat provision for a wide variety of flora and fauna along with their recreation values necessitates their sustainable management through appropriate conservation mechanisms. Failure to restore these ecosystems will result in extinction of species or ecosystem types and cause permanent ecological damage. In Bangalore, lentic ecosystems (for example lakes) have played a prominent role serving the needs of agriculture and drinking water. But the burgeoning population accompanied by unplanned developmental activities has led to the drastic reduction in their numbers (from 262 in 1976 to 81). The existing water bodies are contaminated by residential, agricultural, commercial and industrial wastes/effluents. In order to restore the ecosystem, assessment of the level of contamination is crucial. This paper focuses on characterisation and restoration aspects of Varthur lake based on hydrological, morphometric, physical-chemical and socio-economic investigations for a period of six months covering post monsoon seasons. The results of the water quality analysis show that the lake is eutrophic with high concentrations of phosphorous and organic matter. The morphometric analysis indicates that the lake is shallow in relation to its surface area. Socio-economic analyses show dependence of local residents for irrigation, fodder, etc. These analyses highlight the need and urgency to restore the physical, chemical and biological integrity through viable restoration and sustainable watershed management strategies, which include pollution abatement, catchment treatment, desilting of the lake and educating all stakeholders on the conservation and restoration of lake ecosystems.

Evaluation of the Quality of Drinking Water in Kerala State, India

The quality of tap water from water supplies from 14 districts of Kerala state, India was studied. Parameters like pH, water temperature, total dissolved solids, salinity, nitrates, chloride, hardness, magnesium, calcium, sodium, potassium, fluoride, sulphate, phosphates, and coliform bacteria were enumerated. The results showed that all water samples were contaminated by coliform bacteria. About 20% of the tap water samples from Alappuzha and 15% samples from Palakkad district are above desirable limits prescribed by Bureau of Indian Standards. The contamination of the source water (due to lack of community hygiene) and insufficient treatment are the major cause for the coliform contamination in the state. Water samples from Alappuzha and Palakkad have high ionic and fluoride content which could be attributed to the geology of the region. Water supplied for drinking in rural areas are relatively free of any contamination than the water supplied in urban area by municipalities, which may be attributed higher chances of contamination in urban area due to mismanagement of solid and liquid wastes. The study highlights the need for regular bacteriological enumeration along with water quality in addition to setting up decentralised region specific improved treatment system.

Contolling Alkali Induced Heave in soil with fly ash

The properties of the soils can change drastically due to the presence of contaminants leading to several geotechnical failures founded on them. One important pollutant that can have considerable effect is the alkali released from varies industries. It is known that alkali solutions can increase the swelling of soil containing both expansive and non-expansive minerals.Many attempts to control this alkali-induced heave in soils through chemical agents were not successful. With a view to study the use of fly ash to stabilize alkali contaminated soil, the behavior of soils containing 25% and 50% of fly ash has been studied in the presence of 2N-alkali solution. Results of volume change behavior of non-expansive soil containing kaolinite clay mineral in the presence of fly ash showed that it is effective to control the alkali induced swelling in the soil. The effectiveness increases with an increase in the percentage of fly ash in soils. Detailed X-ray diffraction and SEM studies showed that the mineralogical changes that occur in soil due to alkali interaction are inhibited in the presence of fly ash.

A Mechanism for the Occurrence of Ions in Distilled Water

Solar distillation can be used to produce potable water from contaminated water. However, studies show that ions such as F(-) and NO(3)(-) occur in distillates from solar stills. In order to understand the reasons for this behavior, imaging and distillation experiments were conducted. White dots were seen in the vapor space above the interface of hot water poured into containers. The concentrations of various ions such as F(-) and SO(4)(2-) in the distillates from thermal and solar distillation experiments were roughly comparable when the feed consisted of deionized water and also solutions having fluoride concentrations of 100 and 10 000 mg/L. These observations suggest that aerosols enter the distillation setup through leaks and provide nuclei for the condensation of water vapor. The water-soluble component of aerosols dissolves in the drops formed, and some of the drops are transferred to the distillate by buoyancy-driven convection.

Photocatalytic degradation of dimethoate using LbL fabricated TiO2/polymer hybrid films

Degradation of dimethoate under UV irradiation using TiO2/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of lamp intensity, catalyst loading in the layers, number of bilayers, pH and initial dimethoate concentration on the degradation of dimethoate was systematically studied. The degradation was monitored using high performance liquid chromatography (HPLC) analysis and total organic carbon (TOC) measurements as a function of irradiation time, to see the change in concentration of dimethoate and mineralization, respectively. Complete degradation of dimethoate was achieved under TiO2 optimum loading of 4 g/L at an UV irradiation time of 180 min. Increase in the lamp intensity, catalyst loading and number of bilayers increased the rate of degradation. At a pH of 4.62, complete degradation of dimethoate was observed. The degradation efficiency decreased with increase in initial dimethoate concentration. The degradation byproducts were analyzed and confirmed by gas chromatography-mass spectra (GC-MS). Toxicity of the irradiated samples was measured using the luminescence of bacteria Vibrio fischeri after 30 min of incubation and the results showed more toxicity than the parent compound. Catalyst reusability studies revealed that the fabricated thin films could be repeatedly used for up to ten times without affecting the photocatalytic activity of the films. The findings of the present study are very useful for the treatment of wastewaters contaminated with pesticides. (C) 2011 Elsevier B.V. All rights reserved.

Cyclodextrin functionalized magnetic iron oxide nanocrystals: a host-carrier for magnetic separation of non-polar molecules and arsenic from aqueous media

A single-step magnetic separation procedure that can remove both organic pollutants and arsenic from contaminated water is clearly a desirable goal. Here we show that water dispersible magnetite nanoparticles prepared by anchoring carboxymethyl-beta-cyclodextrin (CMCD) cavities to the surface of magnetic nanoparticles are suitable host carriers for such a process. Monodisperse, 10 nm, spherical magnetite, Fe3O4, nanocrystals were prepared by the thermal decomposition of FeOOH. Trace amounts of antiferromagnet, FeO, present in the particles provides an exchange bias field that results in a high superparamagnetic blocking temperature and appreciable magnetization values that facilitate easy separation of the nanocrystals from aqueous dispersions on application of modest magnetic fields. We show here that small molecules like naphthalene and naphthol can be removed from aqueous media by forming inclusion complexes with the anchored cavities of the CMCD-Fe3O4 nanocrystals followed by separation of the nanocrystals by application of a magnetic field. The adsorption properties of the iron oxide surface towards As ions are unaffected by the CMCD capping so it too can be simultaneously removed in the separation process. The CMCD-Fe3O4 nanocrystals provide a versatile platform for magnetic separation with potential applications in water remediation.

Lead Retention by Soils at Field Moisture Contents

The majority of studies pertaining to lead retention by clays and soils have examined the mechanisms, kinetics, and adsorption isotherms using the batch experiment technique that employs solid: water extracts of 1:10 and 1:20. Field soil deposits generally have much lower gravimetric water content ranging between 9 and 45%. Given the wide disparity in the solids: water ratio employed in the batch experiment technique and that prevailing in field deposits, this paper examines the lead retention characteristics of soils at field moisture contents (6%, 13%, and 25%) using artificially lead-contaminated soil specimens. A residually derived (i.e., formed by in-situ weathering of parent rock) red soil was used to prepare the artificially contaminated soil specimens. The impact of variations in clay content on lead retention was examined by diluting the residual soil with various amounts (0 to 60%) of river sand. Soil specimens remolded at 6 and 13% moisture contents produced very stiff to hard soils on compaction, while specimens remolded at 25% moisture content existed in the slurry state. The soil specimens were contaminated with low (30mg/kg) to high (2500mg/kg) concentrations of lead ions by remolding them with 160ppm to 10,000ppm ionic lead solutions. Lead retention by soils at field moisture contents was determined by extracting the lead from the soil using a water leach test. Experimental results showed that the bulk (71 to 99%) of the added lead was retained by the soil in insoluble form at the field moisture content. Correlations between the amount of lead retained and soil/solution parameters indicated that the amounts of Pb retained at field moisture content is a function of the initial Pb addition, total sand content, effective clay porosity, and soil pH.

Contaminants removal by bentonite amended slow sand filter

Earlier studies have indicated that variability in size, surface texture and charge greatly influence the contaminant removal process in granular media. Based on surface characteristics of montmorillonite, it is anticipated that small addition of this clay would increase adhesion sites for bacterial growth and extracellular polymer production in the slow sand filter and thereby enhance its contaminant removal ability. Experiments were performed by permeating groundwater contaminated with pathogens (total coliform and E. Coli) and inorganic contaminants through the bentonite amended slow sand filter (BASSF). Surprisingly, the BASSF retained inorganic contaminants besides pathogens. Water-leach tests (pH of water leachate ranged from 2 to 9) with spent BASSF specimen indicated that the inorganic contaminants are irreversibly adsorbed to a large extent. It is considered that the combined effects of enhanced-organic matter mediated adhesion sites and increased hydraulic retention time enables the BASSF specimen to retain inorganic contaminants. It is envisaged that BASSF filters could find use in treating contaminated groundwater for potable needs at household and community level.

The design of polyaniline based sensor for the qualitative estimation of malonaldehyde

The detection of contaminated food in every stage of processing required new technology for fast identification and isolation of toxicity in food. Since effect of food contaminant are severe to human health, the need of pioneer technologies also increasing over last few decades. In the current study, MDA was prepared by hydrolysis of 1,1,3,3-tetramethoxypropane in HCl media and used in the electrochemical studies. The electrochemical sensor was fabricated with modified glassy carbon electrode with polyaniline. These sensors were used for detection of sodium salt of malonaldehyde and observed that a high sensitivity in the concentration range similar to 1 x 10(-1) M and 1 x 10(-2) M. Tafel plots show the variation of over potential from -1.73 V to -3.74 V up to 10(-5) mol/L indicating the lower limit of detection of the system. (C) 2013 Elsevier Ltd. All rights reserved.

Graphene Oxide-MnFe2O4 Magnetic Nanohybrids for Efficient Removal of Lead and Arsenic from Water

We show that the hybrids of single-layer graphene oxide with manganese ferrite magnetic nanoparticles have the best adsorption properties for efficient removal of Pb(II), As(III), and As(V) from contaminated water. The nanohybrids prepared by coprecipitation technique were characterized using atomic force and scanning electron microscopies, Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and surface area measurements. Magnetic character of the nanohybrids was ascertained by a vibrating sample magnetometer. Batch experiments were carried out to quantify the adsorption kinetics and adsorption capacities of the nanohybrids and compared with the bare nanoparticles of MnFe2O4. The adsorption data from our experiments fit the Langmuir isotherm, yielding the maximum adsorption capacity higher than the reported values so far. Temperature-dependent adsorption studies have been done to estimate the free energy and enthalpy of adsorption. Reusability, ease of magnetic separation, high removal efficiency, high surface area, and fast kinetics make these nanohybrids very attractive candidates for low-cost adsorbents for the effective coremoval of heavy metals from contaminated water.

Effect of measurement noise on Granger causality

Most of the signals recorded in experiments are inevitably contaminated by measurement noise. Hence, it is important to understand the effect of such noise on estimating causal relations between such signals. A primary tool for estimating causality is Granger causality. Granger causality can be computed by modeling the signal using a bivariate autoregressive (AR) process. In this paper, we greatly extend the previous analysis of the effect of noise by considering a bivariate AR process of general order p. From this analysis, we analytically obtain the dependence of Granger causality on various noise-dependent system parameters. In particular, we show that measurement noise can lead to spurious Granger causality and can suppress true Granger causality. These results are verified numerically. Finally, we show how true causality can be recovered numerically using the Kalman expectation maximization algorithm.