Aerobiology Of Penicillium and Aspergillus Type Spores

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Aerobiology Of Penicillium and Aspergillus Type
Spores

• By
• Abeer Khattab and Estelle Levetin

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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.

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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.

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Aspergillus niger Penicillium
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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.

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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.

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• 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.

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Effect of sampler orifice on Penicillium/Aspergill
us 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.

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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.

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Standard Orifice
Alternate Orifice
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Outdoor Air Sample from Burkard Spore Trap
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RESULTS

• Pen/Asp spores were registered on 362 days in
  2005 with peak concentration on 1 Oct with 1853
  spores/m3.
• August had the highest monthly mean concentration
  of 525 spores/m3.
• April had the lowest mean concentration at 131
  spores/m3.
• Pen/Asp spores represented 5.7 of the yearly
  total spore load (standard orifice).

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Effect of meteorological conditions

• There was a positive significant correlation
  between the concentration of Pen/Asp spores and
  mean daily temperature (r 0.666, plt0.01)
• There was a negative significant correlation
  between the concentration of Pen/Asp spores and
  precipitation (r - 0.122, 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 0.0456, p 0.385) throughout the year.

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Effect of the Burkard Orifice Size on
Penicillium/Aspergillus Spore Concentrations

• July 1st - Oct 31, 2005 data
• Standard orifice mean Pen/Asp spore concentration
  was 477 spores/m3 while that of the alternate
  orifice was 744 spores/m3
• Mean from alternate orifice was significantly
  higher than that of the standard orifice (t
  -8.8, plt0.01)
• There were no significant differences between
  total airborne fungal spore concentrations with
  the two orifices (t -0.93, pgt.01)

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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.