Fungal Colonization of Air Filters and Insulation in a Multi-Story Office Building: Production of Volatile Organics

Secondary air filters in the air-handling units on four floors of a multi-story office building with a history of fungal colonization of insulation within the air distribution system were examined for the presence of growing fungi and production of volatile organic compounds. Fungal mycelium and conidia of Cladosporium and Penicillium spp. were observed on insulation from all floors and both sides of the air filters from one floor. Lower concentrations of volatile organics were released from air filter medium colonized with fungi as compared with noncolonized filter medium. However, the volatiles from the colonized filter medium included fungal metabolites such as acetone and a carbonyl sulfide-like compound that were not released from noncolonized filter medium. The growth of fungi in air distribution systems may affect the content of volatile organics in indoor air. Received: 2 June 1997 / Accepted: 13 June 1997     

Contribution of leaf surface fungi to the air spora

High concentrations of airborne fungal spores frequently occur from spring through fall in temperate areas of the world. Although it is generally assumed that fungi on leaf surfaces are contributors to the air spora, little data are available comparing the types of fungi found on leaf surfaces with those in the atmosphere. Air sampling was carried out with a Burkard Spore Trap located on the roof of a building on the University of Tulsa campus using standard methods. Leaf samples were aseptically collected from Ulmus americana and Quercus palustris trees on campus, placed in sterile plastic bags, and brought to the lab. For each leaf, 4 cm² areas of both upper and lower leaf surfaces were swabbed and plated on malt extract agar with streptomycin. Cultures were incubated at room temperature for 5–7 days and then examined microscopically. Results were expressed as colony forming units (CFU)/cm². Twenty-one fungal taxa were identified from the air samples. The most abundant taxa were Cladosporium, ascospores, basidiospores, and Alternaria; together these four spore types comprised over 90% of the yearly total. Yeasts were the most abundant fungi isolated from both leaf types. Among the mycelial fungi were Phoma species, followed by Cladosporium and Alternaria. Overall twenty genera of filamentous fungi were identified. Yeasts and Phoma are normally splash dispersed and were not identified in the Burkard air samples. However, 10 taxa isolated from leaf surfaces were registered in air samples. Crude estimates of the leaf surface area of each tree suggest that the total fungal load was approximately 5.04×10⁸ CFU for Ulmus and 2.71×10⁸ CFU for Quercus. Of these levels, 19% were from fungi also detected in air samples. The data suggest that some leaf-surface fungi are major contributors to the air spora.     

Transport efficiency and deposition velocity of fluidized spores in ventilation ducts

Experiments with dry, fluidized spores were conducted in a test apparatus to delineate the extent of spore contamination and deposition behavior under normal airflow conditions within a ventilation system. The surrogate biological warfare agent used in experiments was the spore-forming bacterium Bacillus atrophaeus. Viable-spore-counting methods were used in the study because they provide the most important number for estimating human health effects. Three common ventilation duct materials were evaluated: flexible plastic, galvanized steel, and internally insulated fiberglass. Transport efficiency ranged from 9 to 13% in steel and fiberglass ducts; transport efficiency was far less (0.1–4%) in plastic duct. Results showed that the deposition of surrogate biological warfare agent was significantly different in the three duct materials evaluated. All experimentally determined, dimensionless deposition velocities were in the range of theoretical predictions for dimensionless roughness, k ⁺=10. All were 10–100 times greater than the velocities predicted for ducts with smoother surfaces, k ⁺=0.1. For plastic duct, greater dimensionless deposition velocities were likely the result of charge forces between spores and surface. However, for the steel duct, a relatively large dimensionless deposition velocity was unexpected. These findings imply that building contamination will likely vary, depending on the specific type of duct material used throughout an affected area. Results of this study may aid in refining existing particle-transport models and remediation activities.     

Effects of extracts of fiberglass insulations on the growth ofAspergillus fumigatus andA. versicolor

Water extracts of thermal and acoustic fiberglass insulations used in the duct work of heating, ventilation and air conditioning (HVAC) systems supported germination of conidia and growth ofAspergillus versicolor (Vuillemin) Tiraboschi 1908–9 andAspergillus fumigatus Fresenius 1863. Urea, formaldehyde and unidentified organics were detected in the extracts. Formaldehyde in concentrations similar to those found in the extracts restricted the growth of both species in enriched media.A. versicolor, the more common species associated with fiberglass insulations, was more resistant to formaldehyde thanA. fumigatus.     

Alnus rubra nodulation capacity of soil under five species from harvested forest sites in coastal British Columbia

Nodulation of Alnus rubra seedlings after inoculation with soil from under A. rubra, Betula papyrifera. Rubus lacianutus, R. spectabilis, and R.ursinus on 2 recently harvested sites was compared. Nodulation capacity was low compared to other published reports, ranging from 0 to 18.9 infective units cm^-3 of soil and was significantly affected by the site and plant species. Nodulation capacity of soil under alder was significantly higher than under all other species except R. spectabilis, regardless of site. The lowest nodulation capacity was found in soil under B. papyrifera.Joint appointment with Dept. of Soil Science, Faculty of Agricultural Sciences     

Formulation of a Streptomyces Biocontrol Agent for the Suppression of Rhizoctonia Damping-off in Tomato Transplants

Formulations of a Streptomyces biological control agent for Rhizoctonia damping-off in tomato seedlings were developed for the first time from vegetative propagules obtained from actively growing, nonsporulating liquid cultures. Alginate beads, durum flour (starch) granules, and talcum powder formulation of this new actinomycetous antagonist (Streptomyces sp. Di-944) isolated from the rhizosphere of field-grown tomato (Lycopersicon esculentum) suppressed damping-off caused by Rhizoctonia solani in tomato plug transplants (cv. Bonny Best) in a peat-based, soilless potting mix under greenhouse conditions. For formulations, vegetative biomass of Streptomyces sp. Di-944 from 3-day-old liquid fermentation in yeast extract–malt extract–glucose broth was lyophilized and pulverized to obtain fragments of viable vegetative filaments. The pulverized biomass had an initial viable count of 2 × 10⁷colony forming units/g and retained 100% viability for 2 weeks when stored at 4°C. Formulations stored at 4°C had a longer shelf life than those stored at 24°C based on viability at 2-week intervals over a 6-month storage period. In addition, dual culture tests showed declining efficacy for surviving Streptomyces propagules in formulations during this storage period. At 4°C, the powder and granular formulations were found to be the most stable and were shown to be 100% viable after 14 and 10 weeks of storage, respectively. However, at the end of 24 weeks, the number of viable propagules in the powder and granular formulations declined to 1.2 × 10⁵ and 7 × 10³ colony forming units/g, respectively. Alginate beads were the least stable in storage. Even at 4°C, 6.9 × 10⁴ and 7.3 × 10² viable propagules/g formulation were detected at the end of 12 and 24 weeks, respectively. The talcum powder formulation delivered to tomato seeds as a seed-coating was the most effective biocontrol treatment. It suppressed damping-off in 10-day-old tomato transplants by almost 90% compared to 30 and 22% damping-off reduction when alginate beads or starch granules were delivered concomitantly with tomato seeds. Seed-coating with powder formulation of the biocontrol agent was as effective as drench application of the fungicide, oxine benzoate (No-Damp), in controlling Rhizoctonia damping-off and superior to the commercial biocontrol agent, Streptomyces griseoviridis (Mycostop), applied to tomato seeds as seed-coating.     

Water Relations Only Partly Explain the Distributions of Three Perennial Plant Species in a Semi-arid Environment

The water relations and stomatal conductances of three perennial plant species, Stipa tenacissima L., Anthyllis cytisoides L., and Retama sphaerocarpa (L.) Boiss., dominant on the upper slopes, mid-slopes and floor of a valley, respectively, in semi-arid south-east Spain, were investigated to test the hypothesis that differences in plant-soil water relations could account for the different distributions of each species in the catena. Diurnal measurements of water potential (Ψ_w), relative water content (RWC) and stomatal conductance (g_s) of leaves were made over one year. Leaf temperature, air humidity, wind-speed and incident quantum flux density were measured concurrently. Soil water content was determined gravimetrically at 0 – 5 cm and 15 – 20 cm depths. Measurements of Ψ_w, RWC and g_s were analysed according to meteorological conditions, based on the maxima for daily air temperature and atmospheric saturation water vapour deficit and on soil moisture content. The hypothesis that plant-soil water relations can explain the distribution of the three species along the catena from valley side to valley floor was rejected for Anthyllis and Stipa but confirmed for Retama. This revised version was published online in July 2006 with corrections to the Cover Date.     

Deposition of ammonia to the forest floor under spruce and beech at the Höglwald site

Laboratory and field measurements of the flux of ammonia to forest floor canopies of spruce and beech stands at the Höglwald site in southern Bavaria are reported. Measurements were performed with an open chamber method. A linearity between ammonia concentration and ammonia flux from the atmosphere to the ground floor canopy was detected. Deposition of ammonia showed no saturation even at air concentrations up to 50 g NH₃ m^–3 air. Temperature, water content and the moss layer of the ground floor canopy had a minor influence on the deposition velocity in laboratory experiments. Deposition velocity of ammonia was higher to the spruce (1.3 cm s^–1), and limed spruce ground floor canopy (1.17 cm s^–1) compared to the beech stand (0.79 cm s^–1). In field studies, a diurnal course of the deposition velocity was detected with highest velocities in midday and minor during night times, but not in the climatic chamber. The flux of ammonia to the ground floor canopy was estimated of app. 10 kg N ha^–1 yr^–1 for the soil under spruce, 9 kg N ha^–1 yr^–1 for the limed spruce and 6 kg N ha^–1yr^–1 for the soil under beech. The fluxes are interpreted as fluxes from the atmosphere to the ground canopies of the stands.     

A report on Penicillium in the intramural and extramural air of residential areas of Nagpur city (India)

Prevalence of different species of Penicillium and their concentrations per cubic meter of air were evaluated with the use of Hi-Air sampler system Mark II (Hi-Media Laboratories Ltd., India) in the air of homes (bed-rooms) at four different sites in Nagpur. At each of these sites, air sampling was done fortnightly in triplicate for 2 years duration from June 2000 to May 2002. The sampling was also done in triplicate for the outdoor air in the vicinity of each home on the same day immediately after the indoor sampling was over. The mean concentration of Penicillium colony forming units at four different sites in the indoor air was 32, 46.9, 35 and 35.4 CFU/m³, respectively, whereas in the outdoor air at these same four sites, the mean concentration was 24, 28, 25 and 25.8 CFU/m³ respectively. The Penicillium concentration in the indoor air was found to be higher in winter than in other seasons (ANOVA, p < 0.05). Concentration of Penicillium spp. in intramural environment was always higher than that in extramural environment. Statistically significant difference existed between intramural and extramural environments at all the sites, with maximum difference at a site, which is old crowded area of the city. During the 2-years investigations, 11 species of Penicillium were isolated from the indoor air while nine species were isolated from the air outside the homes. The dominant species of Penicillium in indoor as well as outdoor air were P. citrinum (33.78 and 32.81), P. oxalicum (19.70 and 22.60), and P. chrysogenum (17.64 and 14.50). The percentage of the Penicillium in the indoor air was 10.70 while it was 8.36 in outdoor air. Indoor air showed the presence of P. glaber and P. sclerotiorum, which were absent in the outdoor air.     

Colonization byCladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

Summary Cladosporium cladosporioides andC. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.     

Biosynthesis of myo-inositol and its role as a precursor of cell-wall polysaccharides in suspension cultures of wild-carrot cells

The biosynthesis of myo-inositol (MI) and its role as a precursor of cell-wall polysaccharides was studied in supension cultures of wild carrot (Daucus carota L.) cells. Suspension cultures, grown in the presence or absence of 2,4-dichlorophenoxyacetic acid for 7 and 14d were incubated with [U-¹⁴C]glucose and [2-³H]MI in the presence of different concentrations of unlabeled MI. Synthesis of [¹⁴C]MI from [U-¹⁴C]glucose occurred under all conditions. The amount of MI synthesized from glucose was sharply reduced when 10 mM MI was provided in the medium. Substantial quantities of ³H were incorporated in arabinose, xylose and galacturonic acid isolated and purified from the cell-wall polysaccharides of the cell cultures in various stages of growth or embryogenesis. No ³H was present in the glucose or galactose units of cell-wall polysaccharides. At the four stages of growth and states of development of the carrot cultures used, the MI oxidation pathway contributed to the synthesis of pentosyl and galacturonosyl units of the cell wall. However, the data indicate that the contribution of the MI oxidation pathway to pentosyl and galacturonosyl units is small.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - MI myo-inositol     

A report on <Emphasis Type="Italic">Penicillium</Emphasis> in the intramural and extramural air of residential areas of Nagpur city (India)

Prevalence of different species of Penicillium and their concentrations per cubic meter of air were evaluated with the use of Hi-Air sampler system Mark II (Hi-Media Laboratories Ltd., India) in the air of homes (bed-rooms) at four different sites in Nagpur. At each of these sites, air sampling was done fortnightly in triplicate for 2 years duration from June 2000 to May 2002. The sampling was also done in triplicate for the outdoor air in the vicinity of each home on the same day immediately after the indoor sampling was over. The mean concentration of Penicillium colony forming units at four different sites in the indoor air was 32, 46.9, 35 and 35.4 CFU/m³, respectively, whereas in the outdoor air at these same four sites, the mean concentration was 24, 28, 25 and 25.8 CFU/m³ respectively. The Penicillium concentration in the indoor air was found to be higher in winter than in other seasons (ANOVA, p < 0.05). Concentration of Penicillium spp. in intramural environment was always higher than that in extramural environment. Statistically significant difference existed between intramural and extramural environments at all the sites, with maximum difference at a site, which is old crowded area of the city. During the 2-years investigations, 11 species of Penicillium were isolated from the indoor air while nine species were isolated from the air outside the homes. The dominant species of Penicillium in indoor as well as outdoor air were P. citrinum (33.78 and 32.81), P. oxalicum (19.70 and 22.60), and P. chrysogenum (17.64 and 14.50). The percentage of the Penicillium in the indoor air was 10.70 while it was 8.36 in outdoor air. Indoor air showed the presence of P. glaber and P. sclerotiorum, which were absent in the outdoor air.     

The Occurrence and Persistence of Mixed Biofilms in Automobile Air Conditioning Systems

Twelve automobile air conditioner systems from six manufacturers and three countries, selected mostly because of complaints of unpleasant odors in the passenger compartment, were examined for microbial growth by direct microscopy and enrichment culture. Mixed populations of fungi and bacteria (with occasional protozoa) were observed in biofilms in at least some of the components from all used units. The aluminum heat exchanger fins from ten evaporators demonstrated bacterial biofilms that yielded Methylobacterium mesophilicum. Penicillium viridicatum colonized components from four units. These bacteria and fungi were recoverable repeatedly from these units during ‘dry’ storage of up to 27 months. This report associates a bacterial-fungal community with disagreeable air quality in some automobiles. Received: 24 March 1999 / Accepted: 13 April 1999     

Assessing the extent and diversity of riparian ecosystems in Sonora, Mexico

Conservation of forested riparian ecosystems is of international concern. Relatively little is known of the structure, composition, diversity, and extent of riparian ecosystems in Mexico. We used high- and low-resolution satellite imagery from 2000 to 2006, and ground-based sampling in 2006, to assess the spatial pattern, extent, and woody plant composition of riparian forests across a range of spatial scales for the state of Sonora, Mexico. For all 3rd and higher order streams, river bottomlands with riparian forests occupied a total area of 2,301 km². Where forested bottomlands remained, on average, 34% of the area had been converted to agriculture while 39% remained forested. We estimated that the total area of riparian forest along the principal streams was 897 km². Including fencerow trees, the total forested riparian area was 944 km², or 0.5% of the total land area of Sonora. Ground-based sampling of woody riparian vegetation consisted of 92, 50 m radius circular plots. About 79 woody plant species were noted. The most important tree species, based on cover and frequency, were willow species Salix spp. (primarily S. goodingii and S. bonplandiana), mesquite species Prosopis spp. (primarily P. velutina), and Fremont cottonwood Populus fremontii. Woody riparian taxa at the reach scale showed a trend of increasing diversity from north to south within Sonora. Species richness was greatest in the willow-bald cypress Taxodium distichum var. mexicanum—Mexican cottonwood P. mexicana subsp. dimorphia ecosystem. The non-native tamarisk Tamarix spp. was rare, occurring at just three study reaches. Relatively natural stream flow patterns and fluvial disturbance regimes likely limit its establishment and spread.     

Biocatalytic properties of lipase in crude latex from babaco fruit (Carica pentagona)

Biocatalytic activities in proteolysis, lipolysis and interesterification reactions were studied for crude latex from the subtropical plant Carica pentagona. The results reveal that crude Carica pentagona latex exhibits equivalent proteolytic activities (5.73 units mg^–1) and lipolytic activities (1.01 units mg^–1) compared to the well-known Carica papaya, the commercially source for papain (4.57 units mg^–1 and 0.90 units mg^–1 respectively). Therefore, in interesterification reactions, Carica pentagona latex shows interesting lipase properties (0.77 units mg^–1) higher than commercial Carica papaya latex (0.28 units mg^–1).     

Screening for lignin degrading bacteria by means of 14C-labelled lignins

Several Nocardia and Pseudomonas spp., as well as some unidentified bacteria, isolated from lake water containing high loads of waste lignin, were tested for their capacity to release ¹⁴CO₂ from specifically ¹⁴C-labelled dehydropolymer of coniferyl alcohol (DHP) or corn stalk lignins. The bacteria were selected according to their ability to degrade phenolic compounds. However, only some of them could release significant amounts of ¹⁴CO₂ from the labelled lignin. The tested Nocardia spp. were more active than the Pseudomonas spp. and the unidentified bacteria. The most active strains belonged to N. autotrophica. These strains released CO₂ significantly from the methoxyl group and transformed the other carbons from the phenylpropane skeleton of lignin also into CO₂. Other less demethylating strains also released little CO₂ from the other carbons of the lignin molecule. From corn stalk materials which were specifically labelled in the lignin part only small amounts of labelled CO₂ were released.Non-Common-Abbreviation Used DHP dehydropolymers of coniferyl alcohol     

Effects of controlled livestock grazing and annual prescribed fire on epigeal termite mounds in a savannah woodland in Burkina Faso

The diversity and abundance of epigeal termite mounds were investigated in response to controlled livestock grazing and annual prescribed fire in a Sudanian savannah-woodland in Tiogo State Forest. Sampling of termite mounds was carried out in 4×4 subplots of 0.25 ha in a split-plot experimental design during the rainy season in 2002. There were two main plots of which one was fenced to exclude livestock grazing and the second exposed to grazing. Each of the main plots included 4 subplots with annual prescribed fire since 1992 and 4 subplots without fire. Data were collected on the number and characteristics of termite mounds. A mean density of 698 mounds ha⁻¹ was recorded. Mounds built by Trinervitermes spp. were the most abundant followed by Cubitermes spp., Macrotermes subhyalinus and M. bellicosus. The large mound-builders Macrotermes spp. dominated the community interms of basal area (96% of the total) and above-ground volume (99%). The diversity of mound types was notaffected by livestock grazing and annual early prescribed fire (P>0.05). There was no statistical effect of livestock grazing on mound density, whereas a strong depressive effect of annual fire was observed for Trinervitermes spp. mound density (P=0.012). In this ecosystem, annual prescribed fire appeared to be the major determinant for termite mound abundance. Received 2 February 2007; revised 23 October 2007 and 21 January 2008; accepted 22 Feburary 2008.     

The influence of a neotropical herbivore (<Emphasis Type="Italic">Lamponius portoricensis</Emphasis>) on nutrient cycling and soil processes

The role of phytophagous insects in ecosystem nutrient cycling remains poorly understood. By altering the flow of litterfall nutrients from the canopy to the forest floor, herbivores may influence key ecosystem processes. We manipulated levels of herbivory in a lower montane tropical rainforest of Puerto Rico using the common herbivore, Lamponius portoricensis (Phasmatidea), on a prevalent understory plant, Piper glabrescens (Piperaceae), and measured the effects on nutrient input to the forest floor and on rates of litter decomposition. Four treatment levels of herbivory generated a full range of leaf area removal, from plants experiencing no herbivory to plants that were completely defoliated (>4,000 cm² leaf area removed during the 76-day study duration). A significant (P<0.05) positive regression was found between all measures of herbivory (total leaf area removed, greenfall production, and frass-related inputs) and the concentration of NO ₃ ⁻ in ion exchange resin bags located in the litter layer. No significant relationship was found between any of the herbivory components and resin bag concentrations of NH ₄ ⁺ or PO ₄ ⁻ . Rates of litter decay were significantly affected by frass-related herbivore inputs. A marginally significant negative relationship was also found between the litter mass remaining at 47 days and total leaf area removed. This study demonstrated a modest, but direct relationship between herbivory and both litter decomposition and NO ₃ ⁻ transfer to the forest floor. These results suggest that insect herbivores can influence forest floor nutrient dynamics and thus merit further consideration in discussions on ecosystem nutrient dynamics.     

Performance of a flat plate,air-lift reactor for the growth of high biomass algal cultures

A flat plate, multi-pass air lift reactor (FPALR) for the culture of photosynthetic organisms was constructed from twin wall acrylic sheet and its performance characterised. When operated at an air input of 2.01 min⁻¹ the multi-pass system had a Reynolds number of 5200 indicating fully turbulent flow. Chlorella vulgaris 211/11c was found to have a stationary phase biomass of 1.48 g 1⁻¹ when grown in the flat plate air lift reactor (FPALR) at 100 μmol m⁻²s⁻¹ compared to 1.11 g 1⁻¹ when cultured in the continually stirred tank reactor (CSTR) at the same PFD (photon flux density). The same organism cultured at 200 μmol m⁻²s⁻¹ achieved a stationary phase biomass of 1.71 g 1⁻¹ in the FPALR. In contrast, Scenedesmus sp. produced a stationary phase biomass of 2.27 g1⁻¹ and 1.27 g1⁻¹, when cultured at 100 μmol m⁻²s⁻¹ in the FPALR and the CSTR respectively. The growth rates of both organisms were also higher in the PFALR.     

Comparative effects of four mycorrhizal fungi on loblolly pine seedlings growing in a greenhouse in a Piedmont soil

Summary A greenhouse study was conducted to evaluate the effect of ectomycorrhizae on loblolly pine (Pinus taeda L.) growing in a Piedmont soil. Pine seedlings were inoculated with one of four species of fungi (Scleroderma aurantium, Pisolithus tinctorius, Thelophora terrestris, andRhizopogon roseolus). The seedlings were grown in pots containing a Cecil sandy clay loam amended to create a gradient of extractable P ranging from 5.9 to 52.5 g/g. After ten months, all colonized seedlings were significantly larger than control seedlings. However, of the four fungi,Scleroderma aurantium mediated a far superior shoot growth response to increasing levels of soil P; the seedlings were significantly larger than those colonized by any other fungus and also had the largest root systems and greatest degree of mycorrhizal colonization.