Aerobiology Of Penicillium and Aspergillus Type Spores By * Abeer Khattab and Estelle Levetin

INTRODUCTION The atmosphere in Tulsa, Oklahoma contains high concentrations and many types of aeroallergens – both fungal spores and pollen. The genera Penicillium and Aspergillus are naturally considered as soil-borne saprophytes, but they have been reported in many studies as important aeroallergens. There are few studies on the aerobiology of Pen/Asp spores.

OBJECTIVES The main objective of this study is to understand the aerobiology of Pencillium and Aspergillus spores, and the effect of meteorological conditions on the concentration of this type of spore.

Aspergillus niger Penicillium Aspergillus niger Penicillium

Penicillium and Aspergillus Spores Penicillium and Aspergillus spores are small (2-6 μm) so they remain airborne for extended time On spore trap slides spores look alike So, they are commonly grouped as Pen/Asp spores.

METHODS Air samples were collected with a Burkard spore trap (standard orifice) that was located on the roof of a building at the University of Tulsa (12m height). Burkard daily slides were analyzed for some of the most common and important airborne fungal spores for one year (2005) by light microscopy using the single traverse method at 1000x.

Cladosporium, Alternaria, Pen/Asp, Curvularia, Drechslera, Ascospores, Basidiospores, Nigrospora, Myxomycetes, Smuts and other spores were the most common counted spores types. The concentration of each spore type as well as the total concentration of all the fungal spores were calculated. Spore data were statistically analyzed to see the relationship with the environmental factors such as wind speed, rain, humidity, and temperature.

Effect of sampler orifice on Penicillium/Aspergillus spore concentrations One difference between samplers is their efficiency in sampling small spores. Sampler efficiency is partially based on the size of its orifice (cut size). The standard orifice captures spores of 3.7 µm and above while the alternate orifice collects spores of 2.17 µm and above. Below these levels sampler efficiency drops off.

Alternate orifice From 1 Jul – 31 Oct 2005 a second Burkard with an alternate orifice was used to see if more spores would be registered The second Burkard was also placed on the roof of the same building. The same method of analysis was used. Statistical analysis (t test) was used to compare the total spore concentrations and Pen/Asp spore concentrations from both samplers.

Alternate Orifice Standard Orifice

Outdoor Air Sample from Burkard Spore Trap

RESULTS Pen/Asp spores were registered on 362 days in 2005 with peak concentration on 1 Oct with 1853 spores/m 3. August had the highest monthly mean concentration of 525 spores/m 3. April had the lowest mean concentration at 131 spores/m 3. Pen/Asp spores represented 5.7% of the yearly total spore load (standard orifice).

Effect of meteorological conditions There was a positive significant correlation between the concentration of Pen/Asp spores and mean daily temperature (r = 0.666, p<0.01) There was a negative significant correlation between the concentration of Pen/Asp spores and precipitation (r = , p= 0.019) There were no significant correlations between Pen/Asp spore concentration and wind speed (r= 0.042, p = 0.422), or relative humidity (r = , p = 0.385) throughout the year.

Effect of the Burkard Orifice Size on Penicillium/Aspergillus Spore Concentrations July 1 st - Oct 31, 2005 data Standard orifice mean Pen/Asp spore concentration was 477 spores/m 3 while that of the alternate orifice was 744 spores/m 3 Standard orifice mean Pen/Asp spore concentration was 477 spores/m 3 while that of the alternate orifice was 744 spores/m 3 Mean from alternate orifice was significantly higher than that of the standard orifice (t = -8.8, p<0.01) Mean from alternate orifice was significantly higher than that of the standard orifice (t = -8.8, p<0.01) There were no significant differences between total airborne fungal spore concentrations with the two orifices (t = -0.93, p>.01) There were no significant differences between total airborne fungal spore concentrations with the two orifices (t = -0.93, p>.01)

CONCLUSIONS Pen/Asp spores were present in the atmosphere throughout the year with the highest concentration in late summer. Pen/Asp spore concentration was affected by the daily average temperature and precipitation. The orifice size of the Burkard sampler influenced the spore capture with higher concentrations registered by the alternate orifice. Using the standard orifice, aerobiologists may be underestimating the importance of airborne Pen/Asp spores.