Indoor bacteria and asthma in adults: a multicentre case-control study within ECRHS II.

Both protective and adverse effects of indoor microbial exposure on asthma have been reported, but mostly in children. To date, no study in adults has used non-targeted methods for detection of indoor bacteria followed by quantitative confirmation.A cross-sectional study of 198 asthmatic and 199 controls was conducted within the European Community Respiratory Health Survey (ECRHS) II. DNA was extracted from mattress dust for bacterial analysis using denaturing gradient gel electrophoresis (DGGE). Selected bands were sequenced and associations with asthma confirmed with four quantitative PCR (qPCR) assays.15 out of 37 bands detected with DGGE, which had at least a suggestive association (p<0.25) with asthma, were sequenced. Of the four targeted qPCRs, Clostridium cluster XI confirmed the protective association with asthma. The association was dose dependent (aOR 0.43 (95% CI 0.22-0.84) for the fourth versus first quartile, p for trend 0.009) and independent of other microbial markers. Few significant associations were observed for the three other qPCRs used.In this large international study, the level of Clostridium cluster XI was independently associated with a lower risk of prevalent asthma. Results suggest the importance of environmental bacteria also in adult asthma, but need to be confirmed in future studies.

Comparison of methods for assessing temporal variation of growth of fungi on building materials.

Fungal growth on indoor surfaces can decay building materials and release hazardous substances that affect indoor air quality. Despite the numerous methods available for growth determination, there is no commonly accepted standard. The goal of this study was to compare five different assay methods for the measurement of fungal growth: cultivation, MS-based determination of ergosterol, beta-N-acetylhexosaminidase activity, quantitative PCR and microscopic spore counting. Three fungal species (Aspergillus puulaauensis, Cladosporium montecillanum and Penicillium polonicum) were grown on three different building materials (two types of acoustic board and wood). Fungal load was determined at different time points. Results from all of the methods, except the spore count, showed good correlation between each other (r=0.6-0.8). Results obtained with the cultivation method had the highest variability among replicate samples (65 %), making it the least reproducible in repeated measurements. However, it also displayed the highest variability in incubation times (149 %), indicating its suitability for detecting transient changes in the physiological state of cells. Similar to the cultivation method, quantitative PCR correlated well with the other methods and had high variability in incubation times but had lower variability among replicate samples. Ergosterol and beta-N-acetylhexosaminidase enzyme activity seemed to be the methods least dependent on the physiological state of the cells. Varying growth dynamics were observed for different species over time with the different assay methods. Each one of the tests provides a different perspective on fungal quantification due to its specific responses to the various stages of fungal growth.

Role of microbial and chemical composition in toxicological properties of indoor and outdoor air particulate matter.

BACKGROUND: Ambient air particulate matter (PM) is increasingly considered to be a causal factor evoking severe adverse health effects. People spend the majority of their time indoors, which should be taken into account especially in future risk assessments, when the role of outdoor air particles transported into indoor air is considered. Therefore, there is an urgent need for characterization of possible sources seasonally for harmful health outcomes both indoors and outdoors. METHODS: In this study, we collected size-segregated (PM(10-2.5), PM(2.5-0.2)) particulate samples with a high volume cascade impactor (HVCI) simultaneously both indoors and outdoors of a new single family detached house at four different seasons. The chemical composition of the samples was analyzed as was the presence of microbes. Mouse macrophages were exposed to PM samples for 24 hours. Thereafter, the levels of the proinflammatory cytokines, NO-production, cytotoxicity and changes in the cell cycle were investigated. The putative sources of the most toxic groups of constituents were resolved by using the principal component analysis (PCA) and pairwise dependencies of the variables were detected with Spearman correlation. RESULTS: Source-related toxicological responses clearly varied according to season. The role of outdoor sources in indoor air quality was significant only in the warm seasons and the significance of outdoor microbes was also larger in the indoor air. During wintertime, the role of indoor sources of the particles was more significant, as was also the case for microbes. With respect to the outdoor sources, soil-derived particles during a road dust episode and local wood combustion in wintertime were the most important factors inducing toxicological responses. CONCLUSIONS: Even though there were clear seasonal differences in the abilities of indoor and outdoor air to induce inflammatory and cytotoxic responses, there were relatively small differences in the chemical composition of the particles responsible of those effects. Outdoor sources have only a limited effect on indoor air quality in a newly built house with a modern ventilation system at least in a low air pollution environment. The most important sources for adverse health related toxicological effects were related to soil-derived constituents, local combustion emissions and microbes.

Comparison of culture and qPCR methods in detection of mycobacteria from drinking waters.

Environmental mycobacteria are common bacteria in man-made water systems and may cause infections and hypersensitivity pneumonitis via exposure to water. We compared a generally used cultivation method and a quantitative polymerase chain reaction (qPCR) method to detect mycobacteria in 3 types of drinking waters: surface water, ozone-treated surface water, and groundwater. There was a correlation between the numbers of mycobacteria obtained by cultivation and qPCR methods, but the ratio of the counts obtained by the 2 methods varied among the types of water. The qPCR counts in the drinking waters produced from surface or groundwater were 5 to 34 times higher than culturable counts. In ozone-treated surface waters, both methods gave similar counts. The ozone-treated drinking waters had the highest concentration of assimilable organic carbon, which may explain the good culturability. In warm tap waters, qPCR gave 43 times higher counts than cultivation, but both qPCR counts and culturable counts were lower than those in the drinking waters collected from the same sites. The TaqMan qPCR method is a rapid and sensitive tool for total quantitation of mycobacteria in different types of clean waters. The raw water source and treatments affect both culturability and total numbers of mycobacteria in drinking waters.

High indoor microbial levels are associated with reduced Th1 cytokine secretion capacity in infancy.

BACKGROUND: Exposure to microbes and their components may affect the maturation of the immune system. We examined the association of house dust microbial content with cytokine-producing capacity at birth and at the age of 1 year. METHODS: Production of TNF-α, IFN-γ, IL-5, IL-8 and IL-10 at birth (n = 228) and at the age of 1 year (n = 200) following 24- and 48-hour whole-blood stimulation with staphylococcal enterotoxin B (SEB), lipopolysaccharide and the combination of phorbol ester and ionomycin was measured. Concentrations of ergosterol (marker for fungal biomass), muramic acid (marker for Gram-positive bacteria) and 3-hydroxy fatty acids with a carbon chain length from 10 to 14 (marker for Gram-negative bacteria) in living room floor dust were analyzed using gas chromatography-tandem mass spectrometry. Five single microbial species or groups were determined using a quantitative polymerase chain reaction method. RESULTS: A high total level of the studied Gram-positive bacteria in general or Mycobacterium spp. in house dust was associated with decreased SEB-stimulated IFN-γ production, especially at the age of 1 year. The total level of indoor fungi analyzed (Penicillium spp., Aspergillus spp. and Paecilomyces variotii group, Trichoderma viride/atroviride/koningii,Wallemia sebi) was also inversely associated with IFN-γ production at the age of 1 year, but this association did not remain significant after adjustment for potential confounders. A few associations were found between microbial exposures and other measured cytokines. CONCLUSIONS: High indoor microbial exposures may affect immune development in early life by reducing T helper type 1 cytokine secretion capacity. The observed hyporesponsiveness may reflect the adaptation of the immune system to environmental antigens. In future, more attention should be paid especially to the immunomodulatory role of exposures to Gram-positive bacteria.

Microbial communities associated with house dust.

House dust is a complex mixture of inorganic and organic material with microbes in abundance. Few microbial species are actually able to grow and proliferate in dust and only if enough moisture is provided. Hence, most of the microbial content originates from sources other than the dust itself. The most important sources of microbes in house dust are outdoor air and other outdoor material tracked into the buildings, occupants of the buildings including pets and microbial growth on moist construction materials. Based on numerous cultivation studies, Penicillium, Aspergillus, Cladosporium, and about 20 other fungal genera are the most commonly isolated genera from house dust. The cultivable bacterial flora is dominated by Gram-positive genera, such as Staplylococcus, Corynebacterium, and Lactococcus. Culture-independent studies have shown that both the fungal and the bacterial flora are far more diverse, with estimates of up to 500-1000 different species being present in house dust. Concentrations of microbes in house dust vary from nondetectable to 10(9) cells g(-1) dust, depending on the dust type, detection method, type of the indoor environment and season, among other factors. Microbial assemblages in different house dust types usually share the same core species; however, alterations in the composition are caused by differing sources of microbes for different dust types. For example, mattress dust is dominated by species originating from the user of the mattress, whereas floor dust reflects rather outdoor sources. Farming homes contain higher microbial load than urban homes and according to a recent study, temperate climate zones show higher dust microbial diversity than tropical zones.

Molecular profiling of fungal communities in moisture damaged buildings before and after remediation--a comparison of culture-dependent and culture-independent methods.

BACKGROUND: Indoor microbial contamination due to excess moisture is an important contributor to human illness in both residential and occupational settings. However, the census of microorganisms in the indoor environment is limited by the use of selective, culture-based detection techniques. By using clone library sequencing of full-length internal transcribed spacer region combined with quantitative polymerase chain reaction (qPCR) for 69 fungal species or assay groups and cultivation, we have been able to generate a more comprehensive description of the total indoor mycoflora. Using this suite of methods, we assessed the impact of moisture damage on the fungal community composition of settled dust and building material samples (n = 8 and 16, correspondingly). Water-damaged buildings (n = 2) were examined pre- and post- remediation, and compared with undamaged reference buildings (n = 2). RESULTS: Culture-dependent and independent methods were consistent in the dominant fungal taxa in dust, but sequencing revealed a five to ten times higher diversity at the genus level than culture or qPCR. Previously unknown, verified fungal phylotypes were detected in dust, accounting for 12% of all diversity. Fungal diversity, especially within classes Dothideomycetes and Agaricomycetes tended to be higher in the water damaged buildings. Fungal phylotypes detected in building materials were present in dust samples, but their proportion of total fungi was similar for damaged and reference buildings. The quantitative correlation between clone library phylotype frequencies and qPCR counts was moderate (r = 0.59, p < 0.01). CONCLUSIONS: We examined a small number of target buildings and found indications of elevated fungal diversity associated with water damage. Some of the fungi in dust were attributable to building growth, but more information on the material-associated communities is needed in order to understand the dynamics of microbial communities between building structures and dust. The sequencing-based method proved indispensable for describing the true fungal diversity in indoor environments. However, making conclusions concerning the effect of building conditions on building mycobiota using this methodology was complicated by the wide natural diversity in the dust samples, the incomplete knowledge of material-associated fungi fungi and the semiquantitative nature of sequencing based methods.

Concentrations and diversity of microbes from four local bioaerosol emission sources in Finland.

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.

Determination of bacterial load in house dust using qPCR, chemical markers and culture.

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.

The occupant as a source of house dust bacteria.

BACKGROUND: Markers for microbial groups are commonly measured in house dust samples to assess indoor exposure to microbes in studies on asthma and allergy. However, little is known about the sources of different microbes. A better understanding of the nature and origin of microbes present in the immediate environment of human beings is crucial if one wants to elucidate protective as well as adverse effects on human health. OBJECTIVE: To determine the extent to which the bacterial composition of mattress and floor dust reflects the presence of the human body in relation to other environmental sources. METHODS: House dust and skin surface swab samples of occupants in 4 homes were collected and analyzed for their bacterial content, using a culture-independent methodology. Bacterial sequences analyzed from the different house dusts and skin surface swabs represented random samples of bacteria present in a given sample. Highly similar sequences were grouped to assess biodiversity and to draw conclusions about the sources of bacteria. RESULTS: The bacterial flora in the house dust samples was found to be highly diverse and dominated by gram-positive bacteria. To a considerable extent, the presence of different bacterial groups was attributed to human sources. In the individuals' mattress dust samples, 69% to 88% of the bacterial sequences analyzed were associated with human origins. The respective percentages for the individual floor dusts ranged from 45% to 55%. CONCLUSION: Our study indicates that human-derived bacteria account for a large part of the mainly gram-positive bacterial content in house dust.

Diversity and seasonal dynamics of bacterial community in indoor environment.

BACKGROUND: We spend most of our lives in indoor environments and are exposed to microbes present in these environments. Hence, knowledge about this exposure is important for understanding how it impacts on human health. However, the bacterial flora in indoor environments has been only fragmentarily explored and mostly using culture methods. The application of molecular methods previously utilised in other environments has resulted in a substantial increase in our awareness of microbial diversity. RESULTS: The composition and dynamics of indoor dust bacterial flora were investigated in two buildings over a period of one year. Four samples were taken in each building, corresponding to the four seasons, and 16S rDNA libraries were constructed. A total of 893 clones were analysed and 283 distinct operational taxonomic units (OTUs) detected among them using 97% sequence similarity as the criterion. All libraries were dominated by Gram-positive sequences, with the most abundant phylum being Firmicutes. Four OTUs having high similarity to Corynebacterium-, Propionibacterium-, Streptococcus- and Staphylococcus- sequences were present in all samples. The most abundant of the Gram-negative OTUs were members of the family Sphingomonadaceae, followed by Oxalobacteraceae, Comamonadaceae, Neisseriaceae and Rhizobiaceae. The relative abundance of alpha- and betaproteobacteria increased slightly towards summer at the expense of firmicutes. The proportion of firmicutes and gammaproteobacteria of the total diversity was highest in winter and that of actinobacteria, alpha- and betaproteobacteria in spring or summer, whereas the diversity of bacteroidetes peaked in fall. A statistical comparison of the libraries revealed that the bacterial flora of the two buildings differed during all seasons except spring, but differences between seasons within one building were not that clear, indicating that differences between the buildings were greater than the differences between seasons. CONCLUSION: This work demonstrated that the bacterial flora of indoor dust is complex and dominated by Gram-positive species. The dominant phylotypes most probably originated from users of the building. Seasonal variation was observed as proportional changes of the phyla and at the species level. The microflora of the two buildings investigated differed statistically and differences between the buildings were more pronounced than differences between seasons.

Indoor air particles and bioaerosols before and after renovation of moisture-damaged buildings: the effect on biological activity and microbial flora.

Many building-related health problems coincide with moisture damage and mold growth within a building. Their elimination is assumed to improve indoor air quality. The aim of this study was to follow the success of remediation in two individual buildings by analyzing the microbial flora and immunotoxicological activity of filter samples. We compare results from samples collected from indoor air in the moisture-damaged buildings before and after renovation and results from matched reference buildings and outdoor air. The microbial characteristics of the samples were studied by analyzing ergosterol content and determining the composition of fungal flora with quantitative polymerase chain reaction (QPCR). In addition, the concentrations of particles were monitored with optical particle counter (OPC). The immunotoxicological activity of collected particle samples was tested by exposing mouse macrophages (RAW264.7) for 24 h to particle suspension extracted from the filters, and measuring the viability of the exposed cells (MTT-test) and production of inflammatory mediators (nitric oxide, IL-6 and TNF*) in cell culture medium by enzyme-linked immunoassay (ELISA). The results show that for Location 1 the renovation decreased the immunotoxicological activity of the particles collected from damaged building, whereas no difference was detected in the corresponding samples collected from the reference building. Interestingly, only slight differences were seen in the concentration of fungi. In the Location 2, a decrease was seen in the concentration of fungi after the renovation, whereas no effect on the immunotoxicological responses was detected. In this case, the immunotoxicological responses to the indoor air samples were almost identical to those caused by the samples from outdoor air. This indicates that the effects of remediation on the indoor air quality may not necessarily be readily measurable either with microbial or toxicological parameters. This may be associated with different spectrum of harmful agents in different mold and moisture-damaged buildings.

Bacterial Exposures and Associations with Atopy and Asthma in Children.

BACKGROUND: The increase in prevalence of asthma and atopic diseases in Western countries has been linked to aspects of microbial exposure patterns of people. It remains unclear which microbial aspects contribute to the protective farm effect. OBJECTIVE: The objective of this study was to identify bacterial groups associated with prevalence of asthma and atopy, and to quantify indoor exposure to some of these bacterial groups. METHODS: A DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE), was applied to mattress dust samples of farm children and control children in the context of the GABRIEL Advanced study. Associations between signals in DGGE and atopy, asthma and other allergic health outcomes were analyzed. Quantitative DNA based assays (qPCR) for four bacterial groups were applied on the dust samples to seek quantitative confirmation of associations indicated in DNA fingerprinting. RESULTS: Several statistically significant associations between individual bacterial signals and also bacterial diversity in DGGE and health outcomes in children were observed. The majority of these associations showed inverse relationships with atopy, less so with asthma. Also, in a subsequent confirmation study using a quantitative method (qPCR), higher mattress levels of specifically targeted bacterial groups - Mycobacterium spp., Bifidobacteriaceae spp. and two different clusters of Clostridium spp. - were associated with a lower prevalence of atopy. CONCLUSION: DNA fingerprinting proved useful in identifying bacterial signals that were associated with atopy in particular. These findings were quantitatively confirmed for selected bacterial groups with a second method. High correlations between the different bacterial exposures impede a clear attribution of protective effects to one specific bacterial group. More diverse bacterial flora in mattress dust may link to microbial exposure patterns that protect against development of atopic diseases.

Actinobacteria in indoor environments: exposures and respiratory health effects.

Actinobacteria are a large group of Gram-positive bacteria common in the environment, especially in the soil. They are morphologically diverse and extremely versatile in their metabolic activities. They produce tens of thousands of secondary metabolites with different biological activities. Exposure to actinobacteria in indoor environments is probably continuous, since they are both common environmental bacteria and human normal flora. However, the occurrence of some species of spore-forming filamentous actinomycetes has been associated with abnormal and health-hazardous situations, such as moisture damage of the building. The measured concentrations of actinobacteria indoors are low. Higher concentrations have been reported during the remediation work of moisture damaged buildings and in agricultural environments. Exposure to high concentrations of actinobacteria can cause allergic alveolitis. Other respiratory disorders have been reported, too and although the measured concentrations are low, the indoor exposure is always a mixture of many different agents, which may have synergistic effects. In vitro and in vivo studies have shown that actinobacteria are very immunoactive and hence, potential causative agents for respiratory and other disorders.

Microbial content of house dust samples determined with qPCR.

This study was designed to produce information about microbial concentrations using qPCR and their variation in different seasons and home environments with analyses of two types of house dust samples. Also the correlations between the two types of samples and the reproducibility of the parallel subsamples were studied. Two types of vacuumed house dust samples, rug dust and vacuum cleaner bag dust, were collected in 5 normal urban homes in four different seasons (N=20+20). From all dust samples, five parallel subsamples were subjected to qPCR analyses of 17 microbial species or assay groups of microbes. The highest fungal concentrations were found for the Penicillium/Aspergillus/Paecilomyces variotii group, and for the species Aspergillus penicillioides, Aureobasidium pullulans, Cladosporium cladosporioides and Cladosporium herbarum. These species/groups were present in almost all samples. The two types of dust samples gave similar results for most microbial species or groups analyzed, but in general, concentrations were slightly higher in rug dust than in dust from vacuum cleaner bag. Microbial concentrations varied significantly between different seasons and hence the similarity of samples within home was mainly low. The concentrations varied significantly also between different home environments. The reproducibility of the parallel subsamples was good or moderate for most of the analyzed species or assay groups. However, further studies are needed to fully understand the factors causing variation in these methods. Nevertheless, in order to show actual differences in fungal concentrations between urban homes with no known microbial sources, all dust samples to be compared should be taken during the same season.

Quantitative PCR analysis of fungi and bacteria in building materials and comparison to culture-based analysis.

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.

Effects of moisture damage and renovation on microbial conditions and pupils' health in two schools--a longitudinal analysis of five years.

Airborne microbes and pupils' symptoms were monitored in a moisture-damaged (index) school and a reference school for five consecutive years. These surveys were carried out in two separate years before the renovation of the index school, during the renovation, and one and two years after the renovation. Microbial concentrations were higher in the index school than those in the reference school before and during renovation, but afterwards, the levels decreased to the level of the reference school. The effect of remediation was seen as an altered mycobiota in the index school. Year-to-year variation of microbial concentrations, probably due to climatic factors, caused a peak in both schools but their difference remained. Several symptoms were more prevalent in the moisture-damaged school than in the reference school, but the differences disappeared during the renovations. These results emphasize the importance of using a reference building in assessing the microbial conditions of a moisture damaged building. Furthermore, microbial concentrations reflected well the technical condition of the construction, but the reported symptoms of the occupants did not strictly follow the timely fluctuation in microbial conditions.

Quantitative measurement of streptomycetes using real-time PCR.

A quantitative real-time PCR method was developed and used for determination of streptomycetes in indoor dust samples of five homes collected during three years. The specificity of the method was tested with 14 Streptomyces and ten non-streptomycetous species, revealing a high specificity for mesophilic streptomycetes. Thermophilic species and S. albus were not efficiently detected. The method gave reproducible results in replicate analyses of the same dust DNA as well as of duplicate DNA isolations. The amount of streptomycetes in house dust was lowest in winter, followed by summer, and highest in spring and fall. The greatest variation in Streptomyces-concentrations was observed in the spring and fall samples.

Characterisation of Streptomyces spp. isolated from water-damaged buildings.

Abstract Saprophytic Streptomyces spp. common in soil and producing biologically active compounds have been related to abnormal microbial growth in buildings where occupants may have health problems. We characterised 11 randomly selected water-damaged building isolates. The 16S rDNA sequence similarity was over 95.4% between strains so that seven, three, and one sequences had greater than 99.8, 99.7 and 99.7% similarity with those of Streptomyces griseus ATCC 10137 (Y15501), Streptomyces albidoflavus DSM 40455(T) (Z76676), and Streptomyces coelicolor A3(2) (Y00411), respectively. Although differences in morphology, pigmentation, fatty acids, biological activity and pH tolerance indicated that strains did not necessarily match with three single phenotypes, they all appeared to belong to two or three branches of Streptomyces spp. most common environmental isolates.