Mold Diversity and Island Biogeography Theory

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• Notes from Dr. Pennings
• This was a nice experiment that tested two clear
  hypotheses. There may have been some problems
  with the methods, but the basic idea was nice
  and the results were explained very well in
  class.

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Mold Diversity and Island Biogeography Theory

• How does the type of bread and bread slice size
  effect mold diversity?

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Mold Facts

• What is mold?
• Kind of Fungus
• What is the energy source for mold?
• Organic matter that is broken down by mold
  enzymes.
• Decaying organic matter allows for mold growth.
• How does mold reproduce?
• Through airborne spores that land on suitable
  surface.
• What are the optimal conditions for mold growth?
• Damp, warm, dark environment

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Question and Hypothesis

• How does the type of bread affect mold diversity?
• Sourdough and breads with no preservatives will
  grow the most diverse mold colonies.
• How does the bread slice size affect mold
  diversity?
• According to the Island Biogeography Theory,
  diversity will increase with size.

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Procedure

• 6 different types of bread were used white with
  preservatives, white with no preservatives,
  wheat, honey wheat, sourdough, and potato.
• A slice of each type of bread was placed in its
  own sandwich bag and sealed.
• The bags were monitored daily for mold growth for
  a period of 2 weeks.
• The bags were unsealed for an hour daily to allow
  for exposure to air.
• The pieces of bread were lightly sprayed with
  water each week to encourage mold growth.

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Procedure

• To test the Island Biogeography Theory, each
  slice of bread was broken into half the size of
  the previous slice.
• To maintain a sterile environment, latex gloves,
  a clean knife, and cutting board were used.
• Species were identified using the Morphological
  Species Concept.
• Experiment was conducted in my dorm room.

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Observationswhite with preservatives6
morphospecies white, green, black, yellow, pink,
orange
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Observationswhite with no preservatives3
morphospecies white, green, black
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Observationswheat3 morphospecies white, green,
black
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Observationshoney wheat5 morphospecies white,
green, black, yellow, red
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ObservationsSourdough4 morphospecies white,
green, black, yellow
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ObservationsPotato2 morphospecies white, green
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Resultseffect of bread type on mold diversity

• White bread with preservatives and honey wheat
  bread had the most number of morphospecies, with
  6 and 5 morphospecies, respectively.

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Resultseffect of bread area on mold diversity

• Mold species and bread area show no correlation.

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Bread Type and Species Area Equation
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Species Area Equations Explained

• The species area equations show that
• there is not a positive relationship between
  bread area and mold diversity.
• bread types exhibited a slope close to zero,
  indicative that there is no relationship between
  bread area and mold diversity.

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Mold Species Dominance and Growth Patterns

• White bread with preservatives showed resistance
  to green mold.
• In all other bread types, green mold dominated in
  area coverage, suggests that green mold is the
  most common species found in the air of my dorm
  room.
• All mold that grew began to grow around the
  perimeter of bread slices. This growth pattern
  can be explained by the handling of bread pieces.
  Bread was handled around the edges of bread. This
  suggests that even in using sterile handling
  techniques mold is ubiquitous in the air.

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Conclusion

• Reject hypothesis that sourdough and breads with
  no preservatives will grow the most diverse mold
  colonies.
• White with preservatives and honey wheat had the
  most number of species, and had red, pink and
  orange molds not present in other bread types.
• Both these breads were Wal-Mart brand, suggesting
  that facilities where bread was manufactured
  already harbored certain mold species.
• Other breads were Natures way brand, had the
  least diverse number of mold species, suggesting
  that these breads grew molds present in
  experimental environment, which were the white,
  green, and black molds.
• Sourdough grew the third most diverse number of
  mold species. Expected because decaying organic
  matter allows for mold growth.
• With disregard to bread brand, different bread
  types mildly effect mold diversity.
• Air dominates over bread type.

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Conclusion

• Reject hypothesis that mold diversity increases
  as bread area increases.
• No correlation existed between mold species and
  bread area, suggesting that mold growth on bread
  operates under a different mechanism than the
  Island Biogeography Theory.
• Different bread areas are not really different
  habitats. They are the same habitat, same bread
  just different sizes.
• Mode of dispersal is by air. Molds present in a
  particular environment seek a suitable surface to
  colonize, regardless of size.