A survey of 39 elementary schools was undertaken to determine indoor air concentrations of bioaerosols within a coastal, temperate climatic zone in British Columbia, Canada. This article reports the results for airborne bacteria. Determinants of exposure were grouped into environmental (outdoor temperature, relative humidity, season, weather), ventilation and comfort parameter (indoor relative humidity, temperature, indoor CO2 concentration, indoor fungal concentration), and occupancy (number of occupants, activity levels, occupancy patterns) variables. Regression modeling was used to evaluate the association between these factors and measured concentrations of indoor mesophilic bacteria. Naturally ventilated rooms (47% of the total rooms surveyed) had higher bacterial counts than mechanically ventilated rooms (geometric mean 325 vs. 166 CFU/m3, respectively, p < 0.001). In univariate analyses, bacterial counts were negatively correlated with supply and exhaust flow rates, air exchange rates, and the percentage of the day that occupants spent quietly sitting at their desks. Analysis of bacterial groups indicated various sources of the bacterial aerosol, with micrococci and staphylococci closely associated with occupancy variables, Bacillus with site and occupancy, and coryneform bacteria with site variables only. Approximately 60% of the variance in the outcome measurement of total bacteria was accountedfor by indoor CO2, lower air exchange rate, the age of the building, signs of current or old moisture stains, room volume, indoor relative humidity, and occupant activity level in a multiple linear regression model, with ventilation factors accounting for 40% of the variance.

No abstract

Exposure to airborne fungal products may be associated with health effects ranging from non-specific irritation of the respiratory tract or mucus membranes to inflammation provoked by specific fungal antigens. While concentrations of airborne fungi are frequently measured in indoor air quality investigations, the significance of these measurements in the absence of visual mold colonization is unclear. This study was undertaken to evaluate concentrations of airborne fungal concentrations in school classrooms within a defined geographic location in British Columbia, Canada, and to build a model to clarify determinants of airborne fungal concentration. All elementary schools within one school district participated in the study. Classrooms examined varied by age, construction and presence or absence of mechanical ventilation. Airborne fungal propagules were collected inside classrooms and outdoors. Variables describing characteristics of the environment, buildings and occupants were measured and used to construct a predictive model of fungal concentration. The classrooms studied were not visibly contaminated by fungal growth. The data were evaluated using available guidelines. However, the published guidelines did not take into account significant aspects of the local environment. For example, there was a statistically significant effect of season on the fungal concentrations and on the proportional representation of fungal genera. Rooms ventilated by mechanical means had significantly lower geometric mean concentrations than naturally ventilated rooms. Environmental (temperature, outdoor fungal concentration), building (age) and ventilation variables accounted for 58% of the variation in the measured fungal concentrations. A methodology is proposed for the evaluation of airborne fungal concentration data which takes into account local environmental conditions as an aid in the evaluation of fungal bioaerosols in public buildings.

Interphase chromosomes were isolated in good yield from four species of fungi. In no case does the chromatin contain histones such as are characteristic of the chromosomes of other eukaryotic organisms.That histones are characteristic chromosomal proteins has been demonstrated for a wide variety of eukaryotic creatures. Thus, the chromosomes of higher plants and animals not only contain histones but, in addition, these proteins are similar in number, chemical properties, and even, in some cases, in primary structure (1, 2). Histones chemically similar to those of higher plants and animals have been found in the green alga Chlorella (3) and in the protozoan Tetrahymena (4,5), as well as in a wide variety of invertebrates.There have been several reports that the nuclei and/or chromatin of fungi lack histones, but contain instead chromosomal proteins of a less basic nature (6-9). We have examined the basic chromosomal proteins of several fungi, using what we believe to be the most rigorous of techniques for both chromatin isolation and histone characterization.We describe methods for obtaining purified fungal chromatin that result in the recovery of at least 70% of the DNA present in the homogenate. The possibility of proteolytic degradation of histones (if present) is unlikely. We find that histones analogous to those cf higher eukaryotes are missing in the fungi we have examined. MATERIALS AND METHODS Chromatin isolationAttempts to isolate chromatin from the fungus M4icrosporum gypseum by the methods suggested for liver and pea (10) were not successful. Fungal nuclei are sheared by these methods, and centrifugal forces sufficient to pellet the chromatin result in gross RNA contamination of the nuclear fraction. A more viscous grinding medium should afford greater protection to the nuclei during the cell breakage step. Stern's glycerol grinding medium admirably satisfied this requirement (11).Sporulation and spore purification procedures for Microsporum have been described previously (12, 13). 2-liter Erlenmeyer flasks, containing 600 ml of glucose (1% w/v) and neopeptone (Difco, 1% w/v) (pH 6.5), were inoculated with 106 conidia per ml and shaken at 350 rpm on a New Brunswick controlled environment dry-air shaker (30"C) for 4 days.The mycelia were harvested by suction filtration. The mycelial mat (150 g wet weight) was washed 4 times with 1-liter amounts of ice-cold physiological saline (pH 6.5).The mycelial mat was resuspended in 350 ml of grinding medium (glycerol 50% w/v, 0.5 M sucrose, 0.001 M CaCl2, and 0.05 M Tris, pH 8). The slurry was poured into an aluminum container and frozen by the addition of liquid nitrogen. Several additions of liquid nitrogen were necessary to completely freeze the material. The frozen slurry was ground to a coarse powder and placed into a Waring blendor. When the temperature of the grinding solution reached -30'C, the blendor was turned to full speed (110 V). Homogenization was continued until the temperature reached 0C. The homogenate was again poured into an aluminum c...

No abstract