Microbiome Study Guide

​The picture shows a petri dish plating method often used in a lab by the scientists to grow bacteria.

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Observing Microorganisms

Multiple Choice

Is there any visible bacterial growth in the petri dish on day 1?

• Yes

• No

Multiple Choice

Is there any visible bacterial growth in the petri dish on day 5?

• Yes

• No

Multiple Choice

Why do you think you can see the growth on day 5 but not on day 1?

• Microorganisms grew bigger in size on day 5

• Microorganisms became visible after multiplying and growing in numbers

• The growth is visible so there are no microorganisms in the petri dish, it's something else

• Microorganisms can not be seen by the naked eye

Multiple Choice

This is the same petri dish on day 9, describe what you are seeing in the petri dish.

• Microorganisms are even more visible because they keep multiplying and growing in numbers

• Some sort of growth but not microorganisms because they are visible

• They are geting bigger in size and becoming a multicellular organism

Multiple Choice

Do you think the microorganisms were present on the first day of plating? Why or why not?

• Microorganisms had to be present on day one, otherwise there shouldn't be any growth

• NO, they were not present. They started growing on day 5

• They were present between day 5 to 9. Day one has no microorganism because I can't see any.

• May be there were some microorganism present on day 1, but most of them started growing on day 5.

Molds are microscopic fungi that live on plant or animal matter. Mold is a type of fungus that causes food spoilage. Sometimes, mold may have white or green fuzzy spots, especially when it's growing on bread. Mold may only appear on the surface, but it has roots underneath. Even if you take the top part of the mold off, its roots will still be in the rest of the food item. Given the proper conditions, mold will start to germinate and grow as early as 24 hours after encountering the moisture source. In 3 to 12 days, the mold spores will colonize. In 18-21 days, the mold can become visible.

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​Fungal growth vs Bacterial growth ​

Multiple Choice

Do you think the fungal growth (Mold) can make you sick on day 5?

• No, because there is no fungus on day 5

• No, fungus cannot hurt you till day 18

• Yes, because fungus is present although we cannot see it

• There is too little fungus to make someone sick on day 5