Bread Mold Analysis Part II

Pre-AP Biology <strong>Bread</strong> <strong>Mold</strong> <strong>Analysis</strong> Using<br />

Methylene Blue and a Scotch Tape Prep<br />

Purpose<br />

To determine the morphology of the sporangiophores, sporangium and the spores that they give rise to in order to<br />

identify a filamentous fungus.<br />

Materials<br />

1. Methylene Blue stain<br />

2. Tooth pick<br />

3. Glass slide<br />

4. Clear scotch tape<br />

5. Fungal culture<br />

Procedure<br />

1. Take a small piece (½ to 1 inch) of clear scotch tape and stick it on the end of a tooth pick.<br />

2. Gently press the sticky side of the tape firmly to the surface of the fungal colony.<br />

3. Pull the tape gently away from the colony.<br />

4. Gently lay the tape, sticky side down, on a clean glass slide and roll the tooth pick to remove it from the<br />

tape. Do not touch the tape. Be careful not to disrupt the fungus that has adhered to the tape.<br />

5. Add a drop of Methylene Blue stain to the edge of the tape so that the stain will distribute under the tape.<br />

6. Examine under the light microscope.<br />

7. Draw what you see in your lab notebook.<br />

<strong>Analysis</strong><br />

1. Describe the fungi that grew on your plate.<br />

2. Can you determine what type of fungi grew on your bread (You may use your text, notes, the internet<br />

and the lab handout to help you identify your fungi.) Reference what you saw on your slide in your<br />

answer. If you cannot make an identification please explain why.<br />

Background for Identification<br />

(this does NOT need to be copied in the lab notebook)<br />

Some of the common bread molds are Penicillium, Aspergillus, Rhizopus, Monascus, and Fusarium. Penicillium<br />

molds usually appear green and grey in color and Aspergillus mold appears similar to Penicillium to the naked eye.<br />

But both are different when examined under a microscopic. In the Aspergillus mold, the fine hairs contain large<br />

balloons with spores inside. Rhizopus appears black as it grows on the surface of the bread<br />

Structure of Fungi<br />

There are two main structures of fungi: sepatate and aseptate. Septate fungi are more advanced and separated<br />

into smaller sections by a septum membrane. Aseptate fungi are more primitive and do not contain septum or<br />

separate sections.

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Identification of Rhizopus (Zygomycota)<br />

The diagrams below denote what Rhizopus would look like under the microscope.<br />

The black specks are tiny sporangium, atop their<br />

stemlike sporangiophores. Spores from the<br />

sporangium are released, often to be carried<br />

away by the wind. If they land in a moist place<br />

they may germinate to form branching, white,<br />

fuzzy stuff called hyphae. All of a fungus's hyphae<br />

considered together are known as its mycelium.<br />

Branching rhizoids behave as roots, anchoring<br />

the fungus into its substrate, releasing digestive<br />

enzymes, and absorbing nutrients for the fungus.<br />

Identification of Penicillium (Ascomycota)<br />

An environmental isolate of Penicillium<br />

1. hypha 2. conidiophore 3. phialide 4. conidia 5. septa<br />

Penicillium sp. 400X