MadSci Network: Microbiology |
Hey Kayla –
This is a really
interesting
question. I am personally very
interested in fungi so I’ll tell you what I know. As you’ve mentioned all of these fungi
are
pretty common on bread. Rhizopus
colonies
tend to be grayish brown and sort of fuzzy.
Penicillium
colonies are almost always teal with a white outline. Aspergillus colonies can range from brown to black and
are
usually fuzzy, like Rhizopus.
All
three of these genera contain several species – you mentioned, for
instance, Rhizopus stolonifer. This is certainly a common species of
Rhizopus, but not the only one that grows on
bread.
Fungi as a kingdom are
separated
into roughly four major phyla based on how they sexually reproduce.
The genera Aspergillus
and Penicillium
belong to Actinomycota. Rhizopus is a Zygomycete.
Now, I’ve already
mentioned
what these three genera look like as colonies.
On a microscopic level Penicillium is definitely the most striking; it sort of
looks
like long, elaborate fans made of cells.
They branch off like coral almost, and are sort of a pale green
color
under the microscope. Aspergillus gets its name from the tool that Catholic
priests
use to sprinkle holy water, called an aspergillum. They have long stalks with a fuzzy ball
at
the end. The fuzzy ball is where the
spores are. Finally, under the
microscope Rhizopus
species just look like tangles of hyphae (fungal
cells) with big balls interspersed between them (these are the zygospores). I
suggest
you use a search engine to find some of the great pictures of these fungi
on
the internet – there are good ones out there.
As far as what they eat,
fungi
aren’t especially finicky eaters.
All
fungi release enzymes into their surroundings that digest large
macromolecules
(like the starch in bread, for instance) and then absorb the smaller
molecules
to use for energy. Starch can be
easily
converted into glucose by these enzymes, and glucose is a great source of
carbon
and energy. The most important
factor
for fungi to grow is moisture – they require a lot of moisture. That’s why you don’t often see fungus on
dried bread crumbs.
I hope this has helped
you
out. I do enjoy talking about fungi…
I
guess you could say I am one fun guy.
Billy.
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