Determination of the collection efficiency of a microbial air sampler

The Biotest RCS Plus air sampler was compared with the well-established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub-micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre-select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro-organisms in a variety of locations.     

Measurement of resuspended aerosol in the Chernobyl area

Results of measurements of the resuspended radioactive aerosols in the Chernobyl area are presented which were obtained soon after the Chernobyl reactor accident and in a European project in 1992–1993. The measurements were carried out with the intention of obtaining a data base for dose assessment of resuspended radioactive particles. Potential significant dose contributions may result from inhalation and secondary contamination due to resuspended radionuclides. In this first article of a series of three papers, the instrumentation and the measurement uncertainties are discussed. An effort was made to sample quantitatively giant aerosol particles (particles larger than 10 μm aerodynamic diameter) as well. The comparison of the samplers shows, in general, an agreement of concentration measurements of ¹³⁷Cs and ⁷Be within a factor of two. One sampler was identified with larger discrepancies and needs additional investigation of its sampling characteristics; for another device, the recalibration of the analysing system is recommended. Ordinary integrating samplers have a loss of about 30% in ¹³⁷Cs activity compared to an isokinetic sampler collecting giant particles as well. The mean ratio of ¹³⁷Cs activity concentration between an instrument sampling only particles larger than 10 μm and an ordinary integrating sampler is 0.39 ± 0.15 during anthropogenic-enhanced resuspension. These findings demonstrate the significant contribution of giant particles to resuspended airborne radioactivity. The results of this study concerning integral measurements during wind-driven resuspension proved to be in good agreement with previously published data on resuspension. Received: 15 May 1997 / Accepted: 4 August 1997     

Performance of the Coriolis air sampler,a high-volume aerosol-collection system for quantification of airborne spores and pollen grains

The Coriolis δ air sampler manufactured by Bertin Technologies (France) is a continuous air sampler, dedicated to outdoor monitoring of airborne spores and pollen grains. This high-volume sampler is based on patented Coriolis technology delivering a liquid sample. The air is drawn into a conical vial in a whirling type motion using suction; particles are pulled against the wall by centrifugal force. Airborne particles are separated from the air and collected in a liquid medium. This innovative solution allows rapid analysis by several techniques including PCR assay and serological assay in order to measure the antigenicity/allergenicity of pollen grains and fungal spores. Also, traditional counting of pollen grains or taxa identification by optical microscopy can be done. A study has been carried out by the Health Protection Agency (HPA), Porton Down, UK, to measure the physical efficiency of the Coriolis air sampler. The physical efficiency of the sampler for collection of micro-organism-laden particles of various sizes has been compared with that of membrane filter samplers using the techniques described by ISO 14698-1. The Coriolis was operated simultaneously with membrane filter samplers in a controlled room where they were challenged with uniform-sized particles of different diameters containing bacterial spores. For the larger particle sizes, it was found that the physical efficiency of the Coriolis was 92% for 10-μm particles. The biological performance of the Coriolis in the collection of airborne fungal spores and pollen grains was evaluated in comparison with a Hirst spore trap (one-week tape-on-drum type sampler) which is one of the most frequently used traps in the measurement of outdoor pollen grain concentrations. The advantages and limitations of both technologies are discussed. The Coriolis was operated simultaneously with a Hirst spore trap in the sampling station of Réseau National de Surveillance Aérobiologique, France (RNSA); the pollen grain and fungal spore counts were analysed by optical microscopy. The pollen grain count m⁻³ collected was compared for both devices. The dispersion values were obtained and statistical analysis was carried out. This study shows that the Coriolis air sampler provided equivalent recovery of pollen grain and fungal spores compared with the volumetric trap standard method (not significantly different, W test, α = 0.05). Nowadays, the French-led project, acronym MONALISA, with financial support from the European Commission––Life-Environment (LIFE05 ENV/F/000068), is testing this innovative air sampler in order to measure the antigenicity/allergenicity of the main aeroallergen particles, i.e. Betula (birch), Poaceae (grasses), Parietaria (pellitory), Olea spp (olive tree), and Artemisia (mugwort) pollen grains, and Alternaria (fungal spores) to validate a new approach of monitoring instead of quantifying pollen grains by their morphology. The robustness and efficiency of the MONALISA system is being demonstrated at a national level throughout Europe in eight different countries with different bio-climatic and topography characteristics: France, UK, Finland, Poland, Spain, Portugal, Switzerland, and Italy.     

A Monitor for Airborne Bacteria

A unique agar drum sampler is described which indicates, continuously, the number of viable, bacterial particles per unit volume of air at the time and point of sampling. By selection of the timer and the sampling rate the sampler is suitable for quite a wide range of concentration and time. An impaction line of 484 in. greatly increases the capacity of this device over slit samplers and other instruments designed to give time-concentration data for viable airborne particles. This sampler should prove useful for: (i) monitoring airborne bacteria in hospitals, public places, and food and industrial plants; (ii) decay rate studies of bacterial aerosols; (iii) evaluation of aerial germicides; (iv) determination of effectiveness of air conditioning systems in removing airborne bacteria; and (v) many other studies in aerobiology.     

Preliminary assessment of protein associated with airborne particles in Mexico City

The protein associated with airborne particles was measured during 1991 as an indicator of airborne biological material in different outdoor urban environments. Fifty air samples were collected simultaneously at three sampling sites, located in the north, south and downtown Mexico City, using a PM10 high-volume sampler (particles<10 μm). The air filters were weighed and protein extracted using a phosphate buffer. Protein concentrations were determined by Lowry assay. The extracts were also analysed by SDS electrophoresis and IEF using a Phastsystem. High concentrations of airborne particles were recorded at the sampling sites with a geometric mean of 70.2 μg/m³ in the south (residential area), 95.5 μg/m³ in the center (urban-commercial area), and with the highest value of 108.9 μg/m³ in the north (urban-industrial area). No statistically significant difference (P>0.05) was observed among the protein concentrations from the sampling sites and the concentrations ranged from non-detectable to 2.54 μg/m³. However, the protein concentrations presented significant difference (P<0.05) with respect to rainy and dry seasons. The Spearman correlation coefficient between protein concentration and airborne particles concentration was statistically significant (r=0.50). The molecular weights (MW) and isoelectric points (pI) for the proteins present in some of the extracts were determined. The values ranged from approximately 8000 to 106 000 Da and the pI values from nearly 4.0 to 5.85. This is important because the major allergens from inhalants are mostly acidic proteins with molecular weights in the range of 20 000–40 000 Da.     

The relationship between food particle size and larval size in Simulium noelleri Friederichs

SUMMARY. 1. In a laboratory experiment, larvae of Simulium noelleri were fed on polystyrene latex microspheres of a range of diameters from 5 to 100 μm.
2. Examination of the particle size distribution in the water used in the experiment showed those <13μm to be the most numerous (87% of all particles present). Particles of this size made up 57±2% (mean ±SE)of the total of those in the gut of larvae.
3. Comparison of particle composition in the gut contents and the water of the experiment, using Jacob's index of electivity, showed that larvae of all sizes filtered proportionally fewer of the particles <13 μm and more of those >13μm.
4. As larvae increased in size they became better able to filter the largest particles present (>52μm in diameter) and less well able to filter the smallest particles (<13μm in diameter).
5. Gut retention time was longer in larger larvae.
6. The biology of S. noelleri , which inhabits lake outlets in high population densities, is considered in the light of these findings.     

Resource utilization by the freshwater deposit feeder Ptychoptera townesi (Diptera: Ptychopteridae)

SUMMARY 1. False crane fly larvae, Ptychoptera townesi (Diptera), occurred in high densities in a flow-controlled section of stream where fine particulate organic matter (FPOM; 0.45 μm to 1 mm in diameter) had accumulated, but were quite rare both upstream and downstream from the section.
2. In laboratory studies, P. townesi grew only on FPOM less than 250 μm. Larvae consistently grew fastest when fed small particles (0.45–53 μm in diameter).
3. Ptychoptera townesi consumed relatively small amounts (0.002 mg per mg animal dry mass day⁻¹) of FPOM (0.45–53 μm). They had long gut content passage times (greater than 19 h) and relatively high efficiencies of conversion of ingested food to body substance (20.7%). Gut content passage times were variable, and depended partially on the nature of the substrate.
4. False crane fly larvae compacted FPOM into faecal pellets considerably larger in size than particles ingested. They lost mass when allowed to feed on their own faecal material, as well as on faeces greater than 250 μm in diameter produced by shredders. However, they survived and grew on shredder faeces (53–500 μm in diameter) that contained a mixture of smaller particles and particles too large for ingestion.
5. The overall pattern of resource utilization by P. townes involved slow handling of relatively small volumes of food, which probably passed once only through a complex alimentary tract.     

A Soluble Fumarate Reductase in Trypanosoma brucei Procyclic Trypomastigotes

ABSTRACT. The enzyme NADH-fumarate reductase associated with the membrane fraction of Trypanosoma brucei procyclic trypomastigotes, can be solubilized by more than 50% when increasing the ionic strength to the equivalent of 150 mM KCI. The apparent K_Ms for NADH (125 μM) and fumarate (50 μM) remain close to those previously reported for the membrane-bound form of this enzyme. Other electron acceptors (i.e. oxygen or cytochrome c) appear to accept electrons in the absence of fumarate (K_M for cytochrome c = 50 μM). The drug L-092,201 (Merck, Sharp and Dohme Research Laboratories, Rahway, NJ), an inhibitor of the membrane-bound fumarate reductase, also blocked the solubilized enzyme. Given the relatively high ionic strength of the intracellular environment we propose that, in vivo, the enzyme fumarate reductase is in the mitochondrial matrix or in the soluble fraction of another intracellular compartment.     

Collaborative study using the preincubation Salmonella typhimurium mutation assay for airborne particulate matter in Japan. A trial to minimize interlaboratory variation.

A collaborative study has been performed over a period of 3 years to develop a suitable method for monitoring the mutagenicity of airborne particulate matter. The study was organized with 8 laboratories and performed in the following steps: (1) selection of a suitable technique for each process involved in the mutagenicity monitoring, (2) developing a tentative protocol by combining systematically the selected techniques, (3) evaluation of the protocol by intra- and inter-laboratory studies, (4) modification of the protocol according to the evaluation, and (5) evaluation of the modified protocol by conducting an interlaboratory study. We found a suitable method for mutagenicity monitoring of particles in the atmosphere. Airborne particles were sampled with a high-volume sampler, the samples were stored at -80 degrees C, extracted by sonication using dichloromethane, solvent-exchanged, and assayed by the preincubation method using Salmonella typhimurium TA98 and TA100. The observed mutagenic activity was normalized with that of an internal standard. Round robin tests revealed that the method resulted in excellent reproducibility. The coefficient of variation for mutagenic activities of airborne particulate samples collected in various districts of Japan were in the range of 14.7 +/- 6.6% to 19.6 +/- 4.0% for strains TA98 and TA100 with and without metabolic activation. We also found that the plate incorporation method was equivalent to the preincubation method for airborne particulate extracts.     

Electronic particle counting for evaluating the quality of air in operating theatres: a potential basis for standards?

Airborne particle counting in eight size ranges (0.5 → 20 μm), by computerized electronic equipment, was compared with the numbers of bacteria-carrying particles (BCP) assessed by slit sampling in ultra-clean and turbulently ventilated operating theatres. In the ultra-clean theatre the number of particles of 5–7 μm size range correlated with BCP while peaks in the numbers of particles <3 μm and > 15 μm corresponded with activity. Comparative relationships also occurred in the turbulently ventilated theatre but the use of this equipment in that environment cannot yet replace counts of airborne bacteria. We consider that electronic particle counting in the 0–20 μm size range may be used to judge the performance of a clean air operating theatre distribution system, including efficiency and integrity of the filter/seal systems and the presence or absence of entrainment of bacteria and other particles. The sampling techniques and analysis of particle concentration results described here may be a suitable basis for standards.     

Pellicle of Paramecium caudatum as Revealed by Freeze Etching

SYNOPSIS. Freeze etching study of Paramecium caudatum surface reveals a regular pattern formed by depressions equipped with a single or paired cilia. This picture is consistent with the generally accepted concept of Paramecium cortex based on conventional methods of study. The surface of the ciliate is covered with small globular particles ∼14 nm in diameter, which have been found also on the plasma membrane of other cells. In the areas where the tips of trichocysts are attached to the pellicle, the globular particles are arranged into circles 0.4 μm in diameter. The whole surface of Paramecium is covered by a smooth thin layer which, always chipped off during fracturing, is detectable only after etching.     

Comparison of methods for quantitative determinations of airborne bacteria and evaluation of total viable counts.

Three different methods of estimating airborne bacteria were compared. An Anderson sampler, a slit sampler, an impinger, and filter samplers with gelatine filters or membrane filters were tested for collection efficiency. The comparisons were made in laboratory experiments with an aerosol of Staphylococcus epidermidis or Serratia marcescens, in field experiments in two different industries, i.e., cotton mill and sewage plant, and in experiments with skin fragment sampling. Experiments were also performed estimating the total number of viable microorganisms on the airborne particles. The Andersen sampler gave the highest bacterial counts in all environments tested. The slit sampler gave statistically lower counts only in the aerosol experiments and cotton mill experiments, where the size of the majority of the particles carrying visible bacteria was 2 to 6 micrometers or smaller. In the sewage plant and skin fragment experiments, where the particles were mainly 5 micrometers or larger, the difference was not significant. The filters were efficient in sampling in skin fragment experiments only. With the agar impingement method, the total viable cell count showed a rising index value with increasing particle size. A mean of 13 bacteria was found per particle in the cotton mill, a mean of 24 in the sewage plant, and a mean of 147 in skin fragment experiments.     

Aerodynamic particle size analysis of aerosols from pressurized metered-dose inhalers: Comparison of andersen 8-stage cascade impactor,next generation pharmaceutical impactor,and model 3321 aerodynamic particle sizer aerosol spectrometer

The purpose of this research was to compare three different methods for the aerodynamic assessment of (1) chloroflurocarbon (CFC)-fluticasone propionate (Flovent), (2) CFC-sodium cromoglycate (Intal), and (3) hydrofluoroalkane (HFA)-beclomethasone dipropionate (Qvar) delivered by pressurized metered dose inhaler. Particle size distributions were compared determining mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), and fine particle fraction <4.7 μm aerodynamic diameter (FPF_{<4.7 μm}). Next Generation Pharmaceutical Impactor (NGI)-size distributions for Flovent comprised finer particles than determined by Andersen 8-stage impactor (ACI) (MMAD=2.0±0.05 μm [NGI]; 2.8±0.07 μm [ACI]); however FPF_{<4.7 μm} by both impactors was in the narrow range 88% to 93%. Size distribution agreement for Intal was better (MMAD=4.3±0.19 μm (NGI), 4.2±0.13 μm (ACI), with FPF_{<4.7 μm} ranging from 52% to 60%. The Aerodynamic Particle Sizer (APS) undersized aerosols produced with either formulation (MMAD=1.8±0.07 μm and 3.2±0.02 μm for Flovent and Intal, respectively), but values of FPF_{<4.7 μm} from the single-stage impactor (SSI) located at the inlet to the APS (82.9%±2.1% [Flovent], 46.4%±2.4% [Intal]) were fairly close to corresponding data from the multi-stage impactors. APS-measured size distributions for Qvar (MMAD=1.0±0.03 μm; FPF_{<4.7 μm}=96.4% ±2.5%), were in fair agreement with both NGI (MMAD=0.9±0.03 μm; FPF_{<4.7 μm}=96.7%±0.7%), and ACI (MMAD=1.2±0.02 μm, FPF_{<4.7 μm}=98%±0.5%), but FPF_{<4.7 μm} from the SSI (67.1%±4.1%) was lower than expected, based on equivalent data obtained by the other techniques. Particle bounce, incomplete evaporation of volatile constituents and the presence of surfactant particles are factors that may be responsible for discrepancies between the techniques.     

Size distribution of allergenic Cry j 2 released from airborne <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> pollen grains during the pollen scattering seasons

Japanese cedar (Cryptomeria japonica) pollinosis is one of seasonal allergic rhinitis that mainly occurs in Japan. The pollinosis is caused by two main kinds of allergenic proteins called Cry j 1 and Cry j 2 which exist in Cryptomeria japonica pollen. In our previous study, we reported that the size-segregated of airborne fine allergenic Cry j 1 and morphological change of Cry j 1 due to the contact with rainfall. However, the study on airborne allergenic Cry j 2 in different particle sizes has not been identified until now. Therefore, the main aim of this study is to investigate the size distribution and scattering behavior of allergenic Cry j 2. The Cry j 2 particles were collected and determined in different particle sizes at the urban sampling points during the most severe pollination season of 2012 in Saitama, Japan. After the size-segregated Cry j 2 allergenic particles were collected using an Andersen high-volume (AHV) atmospheric sample, the airborne Cry j 2 concentrations were determined with a surface plasmon resonance (SPR) method. At the same time, the airborne Cryptomeria japonica pollens were also counted by the Durham pollen sampler. The higher concentrations of the allergenic Cry j 2 were detected even in particle sizes equal to or less than 1.1 μm (PM_1.1) than other particle sizes. The airborne particles ranges from 0.06 to 11 μm were also collected by a low-pressure impactor (LPI) atmospheric sampler. After that, the concentrations of Cry j 2 allergenic particles in fine particle sizes were measured by the SPR method either. With the help of this study, we have confirmed the existence of fine daughter allergenic particles, which clearly differ from the parent pollen grains in size, especially after the rainy days. It is possible that the daughter allergenic species will be released from the fractions of cell wall and burst pollen grains. We concluded that rainwater was one of the important factors that affects the release of pollen allergenic proteins of both Cry j 1 and Cry j 2 from the parent pollen grains.     

A portable sampler (PARTRAP FA 52) for microbiological evaluation of airborne particles: comparison with standard sedimetric and volumetric methods in haemodialysis rooms

Experiments for microbiological evaluation of airborne particles were led in two haemodialysis rooms at the beginning and at the end of activity time (6 h). The efficiency of a new personal and portable aerobiological sampler in comparison with a fixed sampler and a traditional sedimetric method was evaluate. The personal and portable sampler allowed a good evaluation of concentration of bacteria and fungi per cubic metres of sampled air. Since its aspiration flow is equal to Minute Ventilation of an adult; this device provides a quantification of inhaled particles. We propose this device for evaluating the risk for patients and sanitary operators, for monitoring air quality and in implementing adequate environmental prophylaxis and for other applications, e.g. environmental applications.     

Statistical correlation between enterovirus genome copy numbers and infectious viral particles in wastewater samples

Aims: Classic virological tests are time consuming and labour‐intensive; real‐time RT‐PCR has proven to be a fast method to detect and quantify enterovirus genomes in clinical and environmental samples. This method is unable to discriminate between infective and noninfective enterovirus particles; few clinical studies have compared real‐time RT‐PCR and viral culture. We wondered if the enterovirus genome quantification could be correlated to the infectivity. Methods and Results: We used the statistical approach to verify our hypotheses to correlate data, obtained by the standard method (most probable number of cytopathic units—MPNCU) and molecular test (real‐time RT‐PCR), on wastewater treatment plant samples. Chi‐squared test was used, considering several cut‐off values (‘50’‐‘100’‐‘200’ genome copy numbers), to determine statistical significance in comparison of the two methods. Chi‐square value was not significant when cut‐off of 50 (P = 0·103) and 100 (P = 0·178) was assumed but was significant with cut‐off of 200 (P = 0·044). Conclusion: This limit, 200 genome copy, could be used as cut‐off value to indicate enterovirus survival in environmental monitoring. Significant and Impact of the Study: To introduce a fast procedure that is able to compensate for disadvantages of cell culture method for viral environmental analyses.     

Preliminary Observations on the Fine Structure of the Pansporoblast of Thelohania bracteata (Strickland, 1913) (Microsporida, Nosematidae) as Revealed by Freeze-Etching Electron Microscopy

SYNOPSIS. The ultrastructure of a microsporidan pansporoblast was observed with freeze-etching electron microscopy. The cross-fractured face of ovoid mature spores, with the upper part of the spore coat fractured off, revealed the spore membrane; the convex face had many small depressions and the concave face bore fine particles. In cross-section the spore-coat was highly laminated and about 0.5 μ in diameter.
In the cytoplasm of the pansporoblast, fluid-filled and finger-print-life profiles of vesicles were observed. The vesicles were approximately 180 nm in diameter and laminated, each lamella being about 15–18 nm thick. In addition to these vesicles, a population of elevations, each with an average diameter of 40 nm, was evenly distributed in the pansporoblast among the spores. No other cytoplasmic organelles were observed within the pansporoblast. The pansporoblast wall was about 15–19 nm thick with particles 15–18 nm in diameter on its outer surface.     

Observations on the Fine Structure of the Nuclear Apparatus of Blepharisma intermedium Bhandary (Ciliata: Spirotricha)

SYNOPSIS. An electron-microscope study of the macronucleus and the micronucleus of Blepharisma intermedium Bhandary has been made. Sections show that the macronucleus is bounded by a double membrane. Inside, there are two types of bodies: (a) small irregular bodies, from 0.05 to 0.2 μ in diameter, and (b) larger bodies, from 0.4 to 0.6 μ in diameter. The former are intrepreted as cut ends of long, branching filaments traversing the nuclear cavity in all directions. They correspond to the DNA filaments obtained by centrifugation and KCN action on the macronucleus. Each filament is made of fibrils aboue 150 Å thick. The large bodies correspond to the nucleoli; they also show a fibrillar structure. They offer the added interest of displaying dense particles, from 100 to 800 Å in size, whose nature and significance are obscure. The micro-nucleus has a double membrane, and the contents are divisible into an electron-dense network and a material of low density which fills the interstices of the network.     

Enhanced Recovery of Airborne T3 Coliphage and Pasteurella pestis Bacteriophage by Means of a Presampling Humidification Technique

This paper reports a series of experiments in which two methods of collecting airborne bacteriophage particles were compared. A standard aerosol sampler, the AGI-30, was evaluated for its competence in measuring the content of bacteriophage aerosols. It was used alone or with a prewetting or humidification device (humidifier bulb) to recover T(3) coliphage and Pasteurella pestis bacteriophage particles from aerosols maintained at 21 C and varied relative humidity. Collection of bacteriophage particles via the humidifier bulb altered both the initial recovery level and the apparent biological decay. Sampling airborne bacteriophage particles by the AGI-30 alone yielded data that apparently underestimated the maximal number of potentially viable particles within the aerosol, sometimes by as much as 3 logs.     

Bioaerosol concentrator performance: comparative tests with viable and with solid and liquid nonviable particles

Aims:  Generally it is more economical to first characterize a concentrator system with nonbiological particles followed by more rigorous bioaerosol testing. This study compares sampling system performance for varions particle types and sizes.
Methods and Results:  Performances of five concentrators were characterized with five nonviable and viable laboratory aerosols, although not every concentrator was tested with all aerosol types. For particle sizes less than c. 6  μ m aerodynamic diameter, similar efficiencies are obtained for all test particles; however, for larger sizes there is a significant difference between liquid and dry particles.
Conclusions:  Aluminium oxide particles provide results over a broad range of sizes with a single test, but the method is less reproducible than other methods. A combination of monodisperse polystyrene spheres and oleic acid droplets provides an accurate representation of the system performance, but ultimately biological particle tests are needed.
Significance and Impact of the Study:  Devices are being developed for concentrating bioaerosol particles in the size range of 1–10  μ m aerodynamic diameter and this study provides insight into data quality for different test methodologies. Also, the results show some current concentrators perform quite poorly.