Gernot Lysek

Changes in airborne fungi from the outdoors to indoor air; large HVAC systems in nonproblem buildings in two different climates

Little is known about the changes in occurrence and distribution of airborne fungi as they are transported in the airstream from the outdoor air through the heating, ventilation, and air conditioning (HVAC) system to the indoor air. To better understand this, airborne fungi were analyzed in the HVAC systems of two large office buildings in different climate zones. Fungal samples were taken in each of the walk-in chambers of the HVAC systems using a six-stage Andersen Sampler with malt extract agar. Results showed that fungal species changed with different locations in the HVAC systems. The outdoor air intake produced the greatest filtration effect for both the counts and species of outdoor air fungi. The colony forming unit (CFU) counts and species diversity was further reduced in the air directly after the filters. The cooling coils also had a substantial filtration effect. However, in room air the CFU counts were double and the mixture of fungal species was different from the air leaving the HVAC system at the supply air outlet in most locations. Diffusion of outdoor air fungi to the indoors did not explain the changes in the mixture of airborne fungi from the outdoor air to the indoor air, and some of the fungi present in the indoor air did not appear to be transported indoors by the HVAC systems.

Airborne Fungi in Non-Problem Buildings in a Southern-Hemisphere Mediterranean Climate: Preliminary Study of Natural and Mechanical Ventilation

There is a growing body of evidence on fungal contami nation in moisture-damaged and complaint buildings worldwide, but little is known about the occurrence and distribution of fungi in healthy non-complaint buildings in a southern-hemisphere climate. The study tested the hypothesis that fungi in healthy buildings are low in numbers and very similar to the numbers and mixtures of species in both the outdoor air and the indoor air in other parts of the world. Fungi were collected using a 6-stage Andersen sampler, and various indoor air quality (IAQ) indicators and a sick-building syndrome (SBS) questionnaire were used in parallel. The results showed that all IAQ parameters were within USA and Canadian guidelines in all the buildings. There was also a low inci dence of SBS complaints and symptoms. The total colo ny-forming unit (CFU) counts were also low, and the range of fungal species was low compared to buildings in other parts of the world. However, the mixture of fun gal genera in the indoor air was different from the out door air. There were also substantial differences be tween indoor locations. At some locations fungi includ ing Aspergillus niger, Penicillium spp. and Alternaria alternata were much higher indoors than outdoors or, as the pathogen Paecilomyces lilacinus, were absent in the outdoor air indicating indoor sources. Differentiation of fungal species was required to identify indoor fungal sources as the outdoor air was not the major source of indoor fungi. The study also demonstrated that evaluat ing the potential exposure to airborne fungi in indoor air requires differentiation to the species level as simple CFU counts could not differentiate between benign and potentially harmful fungi.

Fluorescence microscopy for the observation of nematophagous fungi inside soil

Fluorochroming of soil samples makes it possible to study soil fungi in their natural habitat. This is demonstrated with some nematophagous (predacious) fungi.

Observation of nematophagous fungi in natural soils by fluorescence microscopy and their correlation with isolation

Thirty natural soil samples were collected from various sites in Berlin. These were nematode-enriched stained with fluorescein-diacetate (FDA) and observed by fluorescence microscopy for the occurrence of nematophagous fungi. The same soil samples were used for the isolation of nematophagous fungi. With the fluorescence microscope 50 observations of these fungi were made including different trapping organs, trapped nematodes nematodes with assimilative hyphae and endoparasites. A total of 65 isolates were obtained in culture representing 38 predators and 27 endoparasites. Network-forming fungi had the highest percentage occurrence in both observation by fluorescence and isolation. Trappers with non-constricting rings were absent. Comparisons of the occurrence of nematophagous fungi observed in natural soils by fluorescence and those isolated showed no consistent relationship. But quantitatively, the number of observed occurrences of nematophagous fungi in soils correlated with number of isolations from the soils.

Determining the Growth and Vitality of Micro-Organisms in Carpets and Mattresses in Non-Problem Dwellings by Measuring CO2 Released during Respiration

Bedroom carpets and mattresses devoid of any reported or observed moisture damage or problems were analysed as sources of indoor fungal growth by determining the amount of CO2 released from respiration by micro-organisms living in furnishings. Dust was extracted from the carpets and mattresses using a Kirby G5 vacuum cleaner. The basal respiration rate of the dust samples without moisture added was used to estimate base respiration rate and a substrate-induced respiration rate method was used to estimate the vitality of micro-organisms in the dust and to estimate the amount of living microbial biomass. Analysis of fungal species was performed by direct sprinkling of dust samples and stamping the filter collection papers directly onto a range of nutrient agars. Fungal differentiation revealed 18 species were living in the carpets and 12 species in the mattresses. Penicillium spp., Aspergillus niger and Zygomycetes were dominant fungi. The relative abundances of fungal species in the carpets were significantly correlated to the species in the mattresses. The basal CO2 respiration rate and the living microbial biomass from all samples was the same as several soil types including sandy loam soils, Para Brown Earth, Sandy Brown Earth and Brown Podzol. The rate of respiration showed that the fungal species detected were living in the furnishings, and were highly metabolically active. This revealed that bedroom carpets and mattresses in non-problem dwellings and without moisture damage can provide a habitat with enough moisture to support fungal growth despite the lack of an obvious moisture source.

Rhythmic growth and sporulation in Trichoderma species: differences within a population of isolates.

Strains of Trichoderma species varied in rhythmic and non-rhythmic growth in light/dark conditions and continuous darkness. About half the strains examined failed to sporulate in the dark indicating dependence on light irrespective of a mechanical trigger. It is concluded that rhythmic growth and sporulation are principally heterogeneous in fungal populations.

Drawing techniques in biology-outline of a postgraduate university course

A practical course for postgraduate students is described in which the drawing techniques used to observe, report, and explain biological structures and developments were taught and practised.