The airborne metagenome in an indoor urban environment

The indoor atmosphere is an ecological unit that impacts on public health. To investigate the composition of organisms in this space, we applied culture-independent approaches to microbes harvested from the air of two densely populated urban buildings, from which we analyzed 80 megabases genomic DNA sequence and 6000 16S rDNA clones. The air microbiota is primarily bacteria, including potential opportunistic pathogens commonly isolated from human-inhabited environments such as hospitals, but none of the data contain matches to virulent pathogens or bioterror agents. Comparison of air samples with each other and nearby environments suggested that the indoor air microbes are not random transients from surrounding outdoor environments, but rather originate from indoor niches. Sequence annotation by gene function revealed specific adaptive capabilities enriched in the air environment, including genes potentially involved in resistance to desiccation and oxidative damage. This baseline index of air microbiota will be valuable for improving designs of surveillance for natural or man-made release of virulent pathogens.     

Criteria for a comfortable indoor environment in buildings

1. 1. The major purpose of buildings is to provide a healthy and comfortable environment for occupants.

2. 2. The indoor environment is a complex system including factors like thermal, visual and acoustic conditions, indoor air quality, electromagnetic fields, static electricity and vibration.

3. 3. To obtain an indoor environment that is acceptable in terms of health as well as comfort, criteria for these factors need to be established.

4. 4. The present paper gives an overview of the criteria recommended in current existing standards and guidelines.

5. 5. As most studies to date have focussed on thermal conditions and indoor air quality, these two factors are described in more detail.

Preliminary survey of indoor and outdoor airborne microfungi at coastal buildings in Egypt

Forty six species and two sterile fungi and yeast species were isolated from samples collected both indoors and outdoors of coastal buildings located in an Egyptian coastal city. Twenty flats from ten buildings were investigated; children living in these buildings have been reported to suffer from respiratory illnesses. Samples were taken using a New Brunswick sampler (model STA-101) operating for 3.0 min at a flow rate of 6.0 l/min. Most of the species isolated have been associated with symptoms of respiratory allergies. Indoors the total culturable fungal count was 1548 CFU/m³; outdoors, it was 1452 CFU/m³. Indoor values of culturable fungal count, total spores count and ergosterol content ranged from 52 to 124 CFU/m³, 100 to 400 spore/m³ and 5 to 27.7 mg/m³, respectively, whereas outdoor levels typically varied between 25 and 222 CFU/m³, 110 and 900 spore/m³ and 3.3 and 67.2 mg/m³, respectively. The maxima for these parameters were detected indoors in house no. 6 and outdoors, outside of house no. 7. The most abundant species were primarily mitosporic (2832 CFU/m³). The most frequent species in both the indoor and outdoor samples were Cladosporium cladosporioides followed by Alternaria alternata and Penicillium chrysogenum,with inside:outside ratios of 1.4, 1.8 and 1.9, respectively. The patterns of fungal abundance were influenced to some extent by changes in the relative humidity and temperature. Other factors, such as type of culture media, rate of sedimentation, size, survival rates of spore and species competition,also affected fungal counts and should be taken into consideration during any analysis of bioaerosol data.     

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins in the indoor environment

The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m3 of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.     

Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling

[This corrects the article on p. 226 in vol. 59.].     

Isolation and identification of indoor airborne fungal contaminants of food production facilities and warehouses in Bursa, Turkey

In this study, we aimed at the isolation and identification of indoor airborne fungal contaminants of 16 different food production facilities and warehouses located in Bursa province (Turkey). Numbers and kinds of microfungi were investigated by exposing a Petri dish of malt extract agar medium for 15 minutes and then counting the number of colonies which develop. Sampling procedure for microfungi was performed 8 times at an interval of 45 days between Dec. 1st 1995--Oct. 15th 1996. A total of 3152 colonies was counted on 864 petri plates in a one year period. As a result, 63 mould species and 4 varieties belonging to 20 genera were isolated by means of pure culture methods. Of these, 7 species and 1 variety belonging to Aspergillus and Penicillium genera are new records for Turkey.     

Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments.     

A survey of airborne algae and cyanobacteria within the indoor environment of an office building in Kuala Lumpur,Malaysia

This study investigates the occurrence of airborne algae and cyanobacteria (AAC) within the indoor environment of an office building in Kuala Lumpur, Malaysia. Samples of air, wall scrapings and soils of potted plants were collected from various sites within the building and surrounding areas. In addition, AAC were collected by exposing a culture medium to the indoor air. Based on the cultured material, 14 taxa of AAC consisting of cyanobacteria such as Phormidium angustissima and Chroococcus minor and chlorophytes such as Chlorella vulgaris and Chlorococcum humicola were recorded. The surrounding areas of the building recorded the highest occurrence (75%) of AAC. Within the building, the highest occurrence of AAC (45%) was recorded on the lower ground floor, an area exposed to the outdoor environment. Some of the AAC recorded were also detected in the wall scraping and soil samples. Areas with heavy human movement appeared to have high occurrence of AAC. Human movement appeared to be an important factor in affecting the dispersal of the AAC.     

Glutathione and plant response to the biotic environment

Glutathione (GSH) is a major antioxidant molecule in plants. It is involved in regulating plant development and responses to the abiotic and biotic environment. In recent years, numerous reports have clarified the molecular processes involving GSH in plant–microbe interactions. In this review, we summarize recent studies, highlighting the roles of GSH in interactions between plants and microbes, whether pathogenic or beneficial to plants.     

Studying the microbiology of the indoor environment

The majority of people in the developed world spend more than 90% of their lives indoors. Here, we examine our understanding of the bacteria that co-inhabit our artificial world and how they might influence human health.     

Profiles of airborne fungi in buildings and outdoor environments in the United States

We examined 12,026 fungal air samples (9,619 indoor samples and 2,407 outdoor samples) from 1,717 buildings located across the United States; these samples were collected during indoor air quality investigations performed from 1996 to 1998. For all buildings, both indoor and outdoor air samples were collected with an Andersen N6 sampler. The culturable airborne fungal concentrations in indoor air were lower than those in outdoor air. The fungal levels were highest in the fall and summer and lowest in the winter and spring. Geographically, the highest fungal levels were found in the Southwest, Far West, and Southeast. The most common culturable airborne fungi, both indoors and outdoors and in all seasons and regions, were Cladosporium, Penicillium, nonsporulating fungi, and Aspergillus. Stachybotrys chartarum was identified in the indoor air in 6% of the buildings studied and in the outdoor air of 1% of the buildings studied. This study provides industrial hygienists, allergists, and other public health practitioners with comparative information on common culturable airborne fungi in the United States. This is the largest study of airborne indoor and outdoor fungal species and concentrations conducted with a standardized protocol to date.     

Utilization of processed pig hair in poultry diets

A commerically prepared sample of pig hair was evaluated in semi-purified and practical diets as a source of essential amino acids for poultry. Amino acid (total) supplementation of pig-hair protein in semi-purified diets indicated that the amino acids were utilized by poultry and that satisfactory performance was obtained when the protein was supplemented with the essential amino acids that analysis had shown to be lacking. The performance of broiler chickens fed on diets containing up to 6% pig hair, and of growing pullets fed on diets containing up to 9% of this material, suggests that properly processed pig hair can be used in rations along with other keratin proteins.     

Chicken anemia virus and avian gyrovirus 2 as contaminants in poultry vaccines

This study focuses on the detection of chicken anemia virus (CAV) and avian gyrovirus 2 (AGV2) genomes in commercially available poultry vaccines. A duplex quantitative real-time PCR (dqPCR), capable of identifying genomes of both viruses in a single assay, was employed to determine the viral loads of these agents in commercially available vaccines. Thirty five vaccines from eight manufacturers (32 prepared with live and 3 with inactivated microorganisms) were examined. Genomes of CAV were detected as contaminants in 6/32 live vaccines and in 1/3 inactivated vaccines. The CAV genome loads ranged from 6.4 to 173.4 per 50 ng of vaccine DNA (equivalent to 0.07 to 0.69 genome copies per dose of vaccine). Likewise, AGV2 genomes were detected in 9/32 live vaccines, with viral loads ranging from 93 to 156,187 per 50 ng of vaccine DNA (equivalent to 0.28–9176 genome copies per dose of vaccine). These findings provide evidence for the possibility of contamination of poultry vaccines with CAV and AGV2 and they also emphasize the need of searching for these agents in vaccines in order to ensure the absence of such potential contaminants.     

Relationship between energy conservation in buildings and indoor air quality

1. 1. Problems with regard to the relationship between energy conservation and indoor air quality in buildings are discussed with a brief history of legislation and practices in Japan since the oil crisis in 1973.

2. 2. In spite of energy conservation as widely advocated the sick building syndrome has hardly been manifested in most of the office spaces in Japan owing to the Law on the Assurance of Healthy Conditions in Buildings which enforced CO₂ concentration to be kept lower than 1000 ppm.

Fungi in the indoor environment of flour mill in Lucknow

Forty species of fungi were recovered from the indoor air of flour mills by exposing petri plates containing potato dextrose, czapek-dox, and sabouraud agar media for 5 minutes. A rotorod sampler was used. The fungal flora of the nearby outdoor environment was also studied for comparison. Species of genus Aspergillus dominated in the mills, being represented by 16 species including one ascosporic species. Other species were of genera Cladosporium and Fusarium. Variations in the fungal population in different months of the survey year were also observed.

Identifiable fungal spores recovered using the rotorod sampler were Alternaria (17% occurrence), Curvularia lunata (10.6%), C. letramera (10%), Cladosporium (19%), Drechslera sp. (9%), Epicoccum sp. (5%), Pithomyces sp. (3%), Nigrospora sp. (10.5%), Stemphylium sp. (4.5%) and Torula sp. (4.5%). Mycelial fragments and unidentifiable spores were also seen in abundance.

Varying allergic responses of patients tested intradermally for the antigens of six Aspergilli, viz., Aspergillus flavus, A. fumigatus, A. melleus, A. niger, A. niveus, and A. terreus were also recorded.     

Monitoring the occurrence of indoor fungi in a hospital

BackgroundThere is a lack of standardized protocols for assessing the presence of indoor fungi. It is thus difficult to compare results from different studies or to measure the effect of indoor fungal presence on occupants.AimsThe aim of the present work was to evaluate the presence of airborne fungal propagules within a hospital taking into account the influence of environmental factors.MethodsThe study was conducted in a hospital over a period of two years. Two portable aerobiological samplers were used: one capturing propagules onto a sticky surface, and the other onto a culture medium consisting of Sabouraud dextrose agar in Petri dishes, supplemented with chloramphenicol. Sampling was performed indoors at four sites (two on the ground floor and two on the third floor, each consisting of an open ward and a closed room). Samples were also taken outdoors. The following factors were considered for fungus occurrence: season, weather conditions, number of people present in the wards, the insulation of the indoor sites and the existence of construction works on the two floors. We carried out 60 ten-minute samples, weekly during the spring (24 samples), and fortnightly for the rest of the year (36 samples).ResultsA total of 2456 colony forming units (CFU) were obtained, with mean propagule concentrations of 107 CFU/m³ outdoors and 24 CFU/m³ indoors. 35330 counts were recorded for propagules. The mean concentrations were 2473 propagules/m³ outdoors and 790 indoors. A statistically significant positive correlation was found between the number of people in one of the wards and fungus occurrence, and the occurrence in both ground floor and third floor rooms was positively correlated with outdoor levels. These showed a seasonal pattern with peaks in summer. Indoors, however, the peaks appeared in spring and autumn. Outdoor construction activities affected the propagule loads but not the number of CFU.ConclusionsThe indoor fungus occurrence in the hospital was independent of meteorological conditions and of insulation from outside of the indoor sites selected, but was correlated with the season and number of people in the third floor ward. Outdoor construction activities affected values of indoor propagules, although seasonality could mask their effect.     

A procedure for evaluation of the indoor environment

Exposure to substances found in the indoor environment is known totrigger respiratory illnesses such as asthma. Despite this knowledge,information on how to identify and remove these exposures is scarce. Toaddress this issue, we describe a program of environmental assessmentdeveloped at Children's Mercy Hospital in Kansas City, Missouri. Weevaluated buildings using a standardized assessment protocol. Thisprotocol included a combination of background information, visualinspection, volumetric air sampling, bulk sampling of suspicious areas,antigen measurement of housedust, and general measurements of the indoorclimate. We inspected a total of 63 buildings including 49 single unitstructures, 4 apartments, 4 town homes, 3 schools, 2 office buildings,and 1 mobile home. Most of these locations were identified because ofrespiratory ailments reported by the occupants. A screeningquestionnaire revealed factors that are known to be associated withfungal contamination such as leaks or flooding in 78% of thebuildings. Visual inspection confirmed these sources of contamination inthe majority of structures. Volumetric air sampling identified a highproportion of buildings with airborneAspergillus/Penicillium species. Stachybotrys wasfound in nearly 30% of these structures both in air and onsurface samples, and surprisingly, Stachybotrys spores werefound only in air in nearly 20%. Climactic factors were onlyweakly associated with fungal contamination. The homes of patients withrespiratory diseases often have significant fungal contamination thatcan be identified with a questionnaire. Using this standardizedapproach, factors associated with respiratory illnesses, usually fungalcontamination, frequently can be identified. Whether removal of theoffending exposure will lead to improve health remains to bedetermined.     

Taylor's law and abrupt biotic change in a smoothly changing environment

Taylor's law (TL), widely verified in empirical ecology, states that the variance of population density approximates a power function of the mean population density, with exponent denoted b. A model of multiplicative increments in population density, where the increments are determined by a Markovian environment, predicts TL with an explicit formula for b. We give a simple theoretical example where, unexpectedly, smooth changes in environmental autocorrelation lead to an abrupt, infinite discontinuity in b. As the daily probability of change in environmental state increases from 0 to 1, b rises from 2 slowly at first, then explodes to +∞ when the population becomes critical, drops to -∞, and rises again to 2. In this model, an exponent b of large magnitude (positive or negative) signals the proximity of a population's criticality and of a singularity in b. A comparable real-world singularity in b could adversely affect fisheries, forestry, agriculture, conservation, and public health.     

Monitoring of Dermanyssus gallinae in free-range poultry farms

Various methods for monitoring Dermanyssus gallinae infestations within free-range egg production units were compared. The study was carried out in five egg-producing free-range poultry buildings infested with D. gallinae. Each farm was divided into six zones (each zone including nest boxes, perches and duckboard) for placing two types of traps (corrugated cardboard and thick card traps) or examining dried droppings for presence of mites. Traps were removed 24 h later, placed into bags and mites were counted at the laboratory using binocular magnification. Droppings were also inspected by eye and mite numbers were estimated. All the methods used allowed us to detect mites although their efficacy differed. The number of mites collected was independent of the type of trap used. Examination of the droppings did not differentiate between buildings with differing mite populations. Placing traps in the nest boxes is a less reliable indicator than placing them on the perches. It appears that the most coherent method for evaluating the D. gallinae population within a free-range flock is to place thick card traps throughout the building, on perches favoured by birds.