Biology Investigation: Fungal Growth Ylenia Attard, Dorianne Galea & Cristina Zammit Page 1 Investigating fungal growth by Ylenia Attard Dorianne Galea Cristina Zammit
Mar 24, 2016
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 1
Investigating
fungal
growth
by
Ylenia Attard
Dorianne Galea
Cristina Zammit
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 2
The following were taken at the beginning of the investigation. All the greenhouses were
prepared by Dorianne Galea at home.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 3
Does salt prevent fungal growth?
Salt will be used to check if it induces fungal growth or if it inhibits it:
After 6 days there was no fungal growth. After 10 days, there was no fungal growth either.
Why?
What we think:
Salt prevents any fungal growth.
Salt induces osmosis from the food to the outside, thus reducing the amount of moisture.
Lack of moisture decreases fungal growth.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 4
Does acidity induce fungal growth, or will it prevent it?
10 drops of lemon were sprinkled every 3 days on
the food item.
After 6 days, fungal growth was very little. This means that acidity helps to prevent fungal
growth.
The following was observed after 10 days:
It can therefore be concluded that acidity reduces fungal growth.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 5
Do fungi need oxygen to grow?
A small window was cut, to allow circulation of air A little fungal growth was observed after 1 week
After 10 days, slightly more fungal growth was observed. In this case, more growth was
expected since oxygen is essential for fungal growth. However, since the plastic was perforated
to create circulation of air, less humidity was observed. This might explain the slow rate of
fungal growth.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 6
A green house having no air was attempted. This had several sources of error since no vacuum
pump was available, implying that practically air was still present. The greenhouse was further
inserted in another plastic bag, to try and remove all surrounding air. This worked in an adverse
way, since it created more humidity, making the fungi grow rapidly.
This was observed after 6 days. One can see the
humidity trapped within the greenhouse.
The next 2 photos were observed after 10 days:
In this case, the result was not as expected. NO fungi should have grown. This set up had
several sources of error, the main one being that it was not vacuumed, and so was not
completely air free. Moreover, it had a lot of trapped humidity. The 2 main factors essential for
fungal growth were therefore present
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 7
Do fungi grow better in a humid or in a dry situation?
Moisture is an essential environmental factor for fungal growth. In this case, water was
sprinkled on the tomatoes regularly. Spores will germinate more in a humid environment, as
can be shown in the following photos, taken after 6 days:
The following was observed after 10 days:
In this case, fungal growth was observed on the outside too. This is because it was regularly
sprinkled with water, enhancing spore germination.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 8
The next set of tomatoes was not sprinkled with water, in an attempt to create a ‘no moisture’
situation. However, the tomato in itself has a lot of water on the inside, thus creating the
perfect environment for fungal growth.
Preparing the set up After 6 days
After 10 days
In this case, the tomato was not the ideal medium to test fungal growth in no moisture! Fungi
do NOT usually grow without moisture. But, the inside of the tomato is very moist, and
therefore has the perfect environment to induce fungal growth. The outside of the tomato is
very well protected by the skin, and therefore not moist; hence lack of fungal growth.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 9
Do fungi grow better in light or in the dark?
In this case 2 carton boxes were used. One was fixed with a bulb on the inside, which was kept
on for 24 hours, throughout the investigation. The other was enclosed within the box, and
therefore exposed to total darkness throughout the investigation. The following was observed
after 6 to 10 days since the investigation was set.
As can be seen, fungal growth was observed in both situations.
This is because fungi do not photosynthesize, and therefore do
not require light.
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 10
Does temperature effect fungal growth?
One set of tomatoes was wrapped in a piece of cloth to create extra warmth. The other set was
placed in a refrigerator. The following were observed after 6 days:
As can be observed, warm temperatures induce rapid fungal growth. In a cold temperature, no
fungal growth should be observed.
The following photos show the rate of fungal growth after 10 days:
Biology Investigation: Fungal Growth
Ylenia Attard, Dorianne Galea & Cristina Zammit Page 11
Conclusion
Factor Growth No Growth
Salt Acidity
Oxygen
No Oxygen Moisture
No Moisture
Light
Darkness
Warm Temperature
Cold Temperature
Therefore, it can be concluded, that in order to avoid fungal growth, a person must store things
in an acidic or salty environment, which has no oxygen and moisture, and at a low temperature.