Mould Growth help!

[deleted-422061]

Hi. I have a Student Research Project for my year 12 biology task to do in my 6 week holiday. It's the first week. I am conducting an experiment to investigate how different environmental conditions affect the growth of mould on bread. This will be carried out for 4 weeks and will have 3 trials. However, at this stage, I'm not completely confident with my experimental set up and how to carry out this investigation with thought out variables, control, how to present my results. I also feel uncertain about how i can have a controlled environment.

Based on my research on mould, the environmental conditions that the mould will be affected differently are: dark places, cold temperature, warm temperature and moisture. The bread will be placed in a ziplock bag. So I will test this in these environments in my household:

- Window seal (exposure to sun; this will have a negative impact on its growth since UV is a disinfectant)
-Wet bread (humid, moist environment; this will encourage positive growth )
-Fridge (cold temperatures; I read that this would slow mould growth)
- rarely opened draw/cupboard (dark place)
-Hot area (I'm not sure where I can test this; maybe the kitchen near the stove)

Are there any other environments in the house I could test? Also, aeration is another factor that influences mould growth. But by having the bread in a sealed ziplock bag, wouldn't that mean I'm not able to test aeration? Because, since the bread is in a bag, there is limited oxygen and therefore is slightly inaccurate.

As with independent and dependent variables and control,

Independent variable: Different environmental conditions
Dependent variable: Number of colonies of fungi (how would I measure this? Can i measure the diameter of the fungi on the bread?)
Control: Im not sure what it is in this case.

[deleted-357169]

Welcome to Science Buddies!

Great project idea! I work with a fungus in my research, so I think this is especially awesome.

Check out this experiment for more experimental set-up help: https://explorable.com/mold-bread-experiment

Taking a page from the experiment I linked to, you could use bread in the freezer as your negative control, you should expect no growth on those slices.

Is there an area that is by a heating vent (or radiator) in your home? That could be your warm condition, since the heat runs more consistently than the stove.

To measure, you could cut each piece of bread into the same size and then you could create a transparent grid of the same size on clear plastic that you would lay on top of the bread to quantify the amount of growth each day (or at whatever interval you want).

Are you inoculating the bread with spores?

[deleted-422061]

I'm going to spray the leave the bread with water and expose it for a few hours so that the mould spores can settle on it.

My hypothesis for this experiment is that: Moulds will have optimal growth in warm and humid environmental conditions.
I'm thinking of testing only sunlit (this would be the window seal, cold (fridge), moist(a relatively more wet bread) and warm environments. Unfortunately, I don't have a heating vent or radiator in my home. Are there are other warm places in the home? Would l it be valid if I just leave the bread near kitchen stove where there would be temporary warm conditions?

Independent variable: Environmental conditions (sunlit area, cold, moisture and warmth). Dependent variable: Area of mould growth on bread. I will use the plastic grid idea to quantify the mould growth. The control would be the bread with No moist, no sunlight and at room temperature. Do you think my hypothesis, variables and control is okay?

[deleted-357169]

Hello again!

You could leave it by the stove but you have to make sure you note that the condition was intermittently warm. It would be misleading to call it a warm condition. Is there a hot water heater closet somewhere in your home? Inside that closet would be warm, but make sure you can safely access it. Is there anywhere else that you can think of that would be warm?

The one that is put into the fridge would only have intermittent light as well, so you should consider that, since you mentioned all would be sunlit.

I think the control of the bread at room temp makes good sense. That is how we normally store bread, so it sounds like a good control to me. Are you putting the control bread into plastic?

Your hypothesis sounds good. As I mentioned above, there are a few more things you should consider about your conditions to make sure you are not adding in any other variables to your experiment. Keep thinking, you're doing a great job!

-AC

[deleted-422061]

I've got a problem now! The mould is growing faster than I expected. It is the 4th day and there are green, orange and black mould on the slices of bread for the control, those in a humid condition and in sunlight. Those in the fridge have no mould growth as expected. yay. I'm just worrying that how would I measure the area of the mould (dependent variable) if the whole surface of the slice of bread is covered with mould because I'll be carrying the experiment for 3 weeks. (My teacher says my project needs to be 'carried over a long period of time'. The only way i can differentiate between them further is through colour and texture observations.

Also,considering the fast growth of the mould, I'm thinking of putting the bags containing the experimental samples into containers to ensure health safety precautions.

[deleted-357169]

Did you teacher specify what a "long period of time" is? Do they know they type of project you are working on?
Fungus does have a rapid growth rate, that's why it is such a great organism to work with in the lab.

You could try to use less moisture to start with, and that could slow down the growth, but like I said earlier, fungus grows quickly.

Just some things to think about. If you remember from the experiment I linked you to above: https://explorable.com/mold-bread-experiment
Their experiment was carried out for 10 days or until there are "significant measurable results". Maybe you could cut it down to 14 days instead of 21 days.

Are you measuring every single day? Because you would want to graph the growth (y axis) as a function of days (x axis).

I agree that secondary containers for the sealed plastic bags would be good. It is always good practice to use secondary containment.

Does your school have an autoclave to dispose of biological waste? If not, when you dispose of the bread, please make sure not to open the bags.

[deleted-422061]

Thanks so much for your reply. I will use containers. No, my teacher didn't specify how long 'over a period of time' it should be. But I heard it must be more than a week because deduction of marks would be applied. I'm thinking of leaving it for 2.5 weeks. I'm just recording my observations in my log book every 1-2 days and on the last day of the experiment, I will measure the area of mould growth on the bread samples using a clear plasticgrid with 1cm squared squares. I'm just wondering, how can i measure the dependent variable which is the area of mould growth now that the fungus would most likely cover the whole surface of the bread. Wouldn't my results be inconclusive?

[deleted-357169]

You should aim to measure every day to show how the growth increases in each condition. And then you could show your data in a line chart. Something like the chart here https://goo.gl/images/woCGGh, except think of the height (y axis) as the diameter of the colonies formed on the bread that you are measuring every single day using the plastic grid. Let me know if you were able to see the image.
The important thing to see is what the the graph will look like at the end. Not every piece of bread will have the same size colonies. Let me know if any of this doesn't make sense. I hope you are enjoying the thought process that goes into designing an experiment!

[deleted-422061]

Doing the experiment was very interesting Thank you for your help. Quick question. Is there a improved way to measure the mould on the bread instead of using a transparent grid with 1cm"2 squares (human error), like a device of some sort? I'm assessing the accuracy of my experiment.

[deleted-357169]

I personally do not know of a better way of measuring.

The beauty of replicates is you get to see if the measurements you took are reproducible!

You should plot all three of your trials using excel or something similar to see what the graph looks like. The exact measurements should be as accurate as possible; however the slope of the line after creating a graph will be the most informative and your replicates will help to account for any measurement error. You can take the average and add error bars for the standard deviation of each set of three.

Let me know if you have any other questions. I hope you are having fun with your project!

[deleted-422061]

My results were unexpected. The mould grew most optimally in sunlight. All the breads were covered. The second most area of mould was found in a humid condition, which is good but it should have been the most optimal condition. The control (no humidity and no sunlight) happened to have a close area of mould to the one in the humid condition. The control contradicts my hypothesis and the facts. What do I do? I'm writing my discussion. I have explained the results, assessed validity, reliability and accuracy and further improvements, but I'm stuck on how do I show/ identitify trend in my results. Like e.g Mould grew optimally in humid and sunlit conditions; when it contradicts the control and the fact that sunlight inhibits mould growth. How do I tackle this in my discussion and conclusion?

[deleted-357169]

Did you make a graph to present your results? Also, how about your fridge bread slices, what happened with them?

You can use your measurements to plot the % of bread covered.

Like this one:

[deleted-422061]

I plotted my results in a column graph, as I didn't measure it everyday as i Should have. But it's okay because thats a improvement that can be made with the experimental method. The mould grew the slowest in the fridge as expected. So the only unexplainable results are the bread mould in the sunlight and the controls.

[deleted-357169]

Have you searched your windows online to find out if they have UV protection?

[deleted-422061]

No the windows have no uv protection.