[Show abstract][Hide abstract] ABSTRACT: Microbial particles can readily be released into the air from different types of man-made sources such as waste operations. Microbiological emissions from different biological sources and their dispersion may be an issue of concern for area planning and for nearby residents. This study was designed to determine the concentrations and diversity of microbiological emissions from four different man-made source environments: waste center with composting windrows, sewage treatment plant, farming environment, and cattle manure spreading. Samples of airborne particles were collected onto polyvinyl chloride filters at three distances along the prevailing downwind direction, from each source environment during a period of approximately 1 week. These samples were analyzed for 13 species or assay groups of fungi, bacterial genus Streptomyces, and Gram-positive and -negative bacteria using quantitative polymerase chain reaction (PCR). Samples for determining the concentrations of viable fungi and bacteria were collected from all environments using a six-stage impactor. The results show that there were variations in the microbial diversity between the source environments. Specifically, composting was a major source for the fungal genera Aspergillus and Penicillium, particularly for Aspergillus fumigatus, and for the bacterial genus Streptomyces. Although the microbial concentrations in the sewage treatment plant area were significantly higher than those at 50 or 200 m distance from the plant area, in the farming environment or cattle manure spreading area, no significant difference was observed between different distances from the source. In summary, elevated concentrations of microbes that differ from background can only be detected within a few hundred meters from the source. This finding, reported earlier for culturable bacteria and fungi, could thus be confirmed using molecular methods that cover both culturable and nonculturable microbial material.
Preview · Article · Dec 2011 · Journal of the Air & Waste Management Association (1995)
[Show abstract][Hide abstract] ABSTRACT: In this study, we developed two novel qPCR-assays for the detection of bacteria in house dust; one that determines the total bacterial amount and another that detects Gram-positive and Gram-negative bacteria separately. The methods were tested in silico and in vitro with microbial strains and vacuum cleaner dust samples, and validated in relation to culture and chemical marker analysis. We also compared the results of these three types of methods (qPCR, culture and chemical marker analysis) in 211 house dust samples from farming and non-farming environments. Microbial concentrations determined by the new qPCR assays (median 7.2 x 10(5) cell equivalents mg(-1)) were about two orders of magnitude higher than concentrations obtained by culture (median 6.7 x 10(3) cfu mg(-1)). The median concentration of muramic acid was 25.67 ng mg(-1) and that of 3-hydroxy fatty acids, expressed as LPS(10-16) was 26.14 pg mg(-1). Correlations between qPCR and chemical markers were moderate, while correlations between culture and qPCR and chemical markers were low to moderate. All the methods used in this study showed that the microbial concentrations are statistically significantly higher (p < 0.001, Mann-Whitney) in farming than non-farming environments.As a conclusion, all tested methods can be used for determining the bacterial load in dust samples, but none of the methods was superior to the others. The results obtained with these methods represent different aspects of bacterial exposure and therefore the results are not expected to be identical with each other.
Full-text · Article · Mar 2010 · Journal of Environmental Monitoring
[Show abstract][Hide abstract] ABSTRACT: During the construction phase of two houses, building material samples were taken for microbial analyses to obtain background information for further investigations on microbial status of buildings. Both culture and qPCR techniques were used for the analyses. It was shown that substantial microbial contamination may occur on materials that are stored outdoors. Simple covering is not enough to prevent moistening of materials in fluctuating seasonal conditions, but dry and well aired storage conditions would be needed. Protection of building materials from harsh weather, damp and microbial growth should be part of quality assurance practices in the construction process of houses.
[Show abstract][Hide abstract] ABSTRACT: We reported previously that moisture damage in living quarters is associated with development of childhood asthma. The aim of this study was to determine whether occurrence of airborne microbes indoors is associated with childhood asthma and with moisture damage. The study consisted of 50 children with new asthma and 50 non-asthmatic children matched for age, gender and place of residence. Homes were inspected for moisture damage and air samples were taken from the living room. Six stage impactor samples were taken onto three growth media and filter samples were taken for the quantitative polymerase chain reaction analyses of Penicillium, Aspergillus, Paecilomyces variotii (Pen/Asp/Pae) group, Cladosporium spp., C. cladosporioides and Streptomyces spp. High concentrations of total viable fungi and occurrence of A. versicolor were associated with childhood asthma. Mold growth in living quarters was associated with viable concentration of Penicillium spp., Aspergillus spp., A. versicolor and yeasts and total concentration of Pen/Asp/Pae group and Streptomyces spp. In conclusion, high concentrations of total viable fungi and occurrence of A. versicolor in air were associated with childhood asthma. In addition, several airborne fungal genera and streptomyces were associated with mold in living quarters.
[Show abstract][Hide abstract] ABSTRACT: Microbes are present everywhere in outdoor air. However, the general characterization of outdoor air mycobiota and bacterial flora is incomplete. In this study, seasonal variations in outdoor air microbial concentrations and differences between a landfill, urban and rural sites were compared. Samples were collected monthly for a period of one year. Airborne dust samples were collected onto polyvinyl chloride filters. Filter samples were analyzed for ergosterol, and 14 species or assay groups of fungi and for the bacterial genus Streptomyces by using quantitative PCR. Viable bacteria and fungi were collected with a cascade impactor twice each month from the three sampling sites. The concentrations in the different sampling sites varied depending on the species. The concentrations of Penicillium and Aspergillus species were significantly higher in the waste center compared with the other sites, while the concentration of Cladosporium spp. was highest in the rural area. The highest concentrations of Streptomyces and Cladosporium species were observed in warmer weather periods. Similar observations were made for ergosterol. Group and species seasonal variation was less distinct for Penicillium and Aspergillus. According to the present results, both season and environment are determinants of microbial communities in outdoor air.
No preview · Article · Jul 2008 · CLEAN - Soil Air Water
[Show abstract][Hide abstract] ABSTRACT: Prolonged moisture on building materials can lead to microbial growth on them. Microbes can emit spores, metabolites and structural parts into the indoor air and thus, cause adverse health effects of people living and working in these buildings. So far, culture methods have been used for assessment of microbial contamination of building materials. In this work, we used quantitative PCR (qPCR) for the detection of selected fungal and bacterial groups in 184 building materials of different types and compared the results with culture-based analysis. Nine either commonly found species, genera or groups of fungi, or those considered as moisture damage indicators, and one bacterial genus, Streptomyces, were determined using qPCR. Fungi and mesophilic actinomycetes were also cultivated using standard media and conditions of the routine analysis. The bacterial genus Streptomyces and the fungal group Penicillium/Aspergillus/Paecilomyces were the most prevalent microbial groups in all building material types, followed by Stachybotrys chartarum and Trichoderma viride/atroviride/koningii. The highest prevalences, concentrations and species diversity was observed on wooden materials. In general, the results of the two methods did not correlate well, since concentrations of fungi and streptomycetes were higher and their occurrence more prevalent when determined by qPCR compared to culture-based results. However, with increasing concentrations, the correlation generally increased. The qPCR assay did not detect Aspergillus versicolor and Acremonium strictum as often as culture.
No preview · Article · Jun 2008 · Journal of Environmental Monitoring
[Show abstract][Hide abstract] ABSTRACT: The majority of Finnish drinking waters fulfill all set regulations and consumers consider the quality as good, but microbiological problems do occur. One such phenomenon is taste and odor problems in distributed water. The essential factors in this regard are actinomycetes and microfungi (molds and yeasts) growing in water reservoirs and in biofilms on the surfaces of distribution pipelines. As previous research data about this matter is scanty, National Public Health Institute began in 2004 a research project to elucidate the occurrence of molds and actinomycetes in Finnish drinking water pipeline networks. This research was activated by a nationwide survey which was answered by 450 waterworks. Of these about 10% had odor or taste problems possibly related to the growth of fungi/actinomycetes in their distributed water. On the basis of this survey, 19 ground- and surface-waterworks having microbiological problems were selected for a study of quality changes during the production and distribution of drinking water. Both molds and actinomycetes were found from all the studied waterworks. Yeasts were found only from four waterworks. Still, the concentrations of molds/actinomycetes were low (below 1000 CFU/L). It was found that the quality of raw water explains in many cases the mold problem of the potable water. The occurrence of actinomycetes, meanwhile was mostly connected with microbial regrowth in the distribution network, especially in networks which did not apply disinfection. The diversity of the problem is reflected in that the occurrence of molds/actinomycetes could not be explained besides the disinfection with other factors like pipeline materials, content of nutrients or temperature.