study of growth of mold (students presentation) · 2018-05-10 · study of growth of mold...

Study of growth of mold(Students’ Presentation)

Objective• To culture bread mould• Compare the growth of mold under

different conditions• Compare the growth of bread mold

when different mediums (sweet bread /plain bread) are provided.

Introduction• 10 samples and 2 controls are included.• 10 samples: 5 pieces of sweet bread and 5

pieces of plain bread• On the bread pieces, we swapped microbes

from different places to see what kinds of fungus will appear on which of the samples.

• 2 controls: a control sample for each: sweet and plain bread

Swapped microbes from different places:

Treatments of Sample Sweet bread Plain breadNone Control

sample 1Control sample 2

Soil Sample 1 Sample 2Spoiled food Sample 3 Sample 4Ventilation duct Sample 5 Sample 6Shoe base Sample 7 Sample 8Rubbish bin Sample 9 Sample 10

Type of bread used Sweet breadMethod of samplingAny moisture added? Water

VentilationWith the zip bag opened a quarter

Place we collected the sample NoTreatment of sample? In shaded area

Control sample 1Day 7

White mold appeared.

Type of bread used plain breadMethod of samplingAny moisture added? Water


Place we collected the sample NoTreatment of sample? In shaded area

Control Sample 2Day 7

Mold appeared!A blue spot

A green spot

Type of bread used Sweet breadMethod of sampling scrapingAny moisture added? Water


Place we collected the sample SoilTreatment of sample? In shaded area

Sample 1Day 7

White moldWhite mold

A green spotWhite mold

Type of bread used Plain breadMethod of sampling scrapingAny moisture added? Water


Place we collected the sample SoilTreatment of sample? In shaded area

Sample 2Day 4

Yellow mold

Sample 2Day 5

Blue mould Black mould

Sample 2Day 6

A blue spot

White mould

Sample 2Day 7

Front BackA green spot A blue spot

Sample 2

• became dry and hard after the seven-day experiment as water is absorbed by the mold.



Place we collected the sample Spoiled foodTreatment of sample? In shaded area

Sample 3Day 2

Yellow mold

Sample 3Day 3

The yellow mold spread.

Sample 3Day 6

The yellow mold became deeperin color.

Sample 3Day 7

Little orange spots

New mold appeared!

Type of bread used plain breadMethod of sampling scrapingAny moisture added? Water


Place we collected the sample Spoiled foodTreatment of sample? In shaded area

Sample 4Day 6

White mold( small amounts)

Sample 4Day 7

Blue spots

White mold



Place we collectedthe sample

ventilation duct

Treatment of sample? In shaded area

Sample 5Day 5

A green spot mold appeared

Sample 5Day 6

The green spot became larger

Sample 5Day 7

Mold becomes larger.



Place we collected the sample

ventilation duct

Treatment of sample? In shaded area

Sample 6Day 6

A blue spotMold appeared!



Place we collected the sample Shoe baseTreatment of sample? In shaded area

Sample 7Day 7

White mold( small amounts)



Place we collected the sample Shoe baseTreatment of sample? In shaded area

Sample 8Day 3

Mold appeared!Black spots

Sample 8Day 6

Black spotsBlue spots

White mold

More mold appeared.

Sample 8Day 7 Green spots

Blue spots

Sample 8

• became dry and hard after the seven-day experiment as water is absorbed by the mold.

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Teacher may ask other students to discuss whether the above observation is really due to the suggested reason or is due to other reason(s) [Does the above phenomenon happens in other samples as well?]



Place we collected the sample rubbish binTreatment of sample? In shaded area

Sample 9Day 7

Green mold



Place we collected the sample rubbish binTreatment of sample? In shaded area

Sample 10Day 7

Remains unchanged.

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This sample (sample 10) was collected from a rubbish bin. Sample 9 was also collected from a rubbish bin. Teacher may ask students why there was mold in sample 9 but none in sample 10. Other students are required to judge whether the suggested answer(s) is/are correct.

ResultsSweet bread

Sample Treatment of sample

No. of Days for mold to appear

No. of Days for odor to appear

Colour of fungus

Control sample

1 7 5 WhiteSample 1 Soil

7 5green, white

Sample 3 Spoiled food 7 4 Yellow, orange Sample 5 Ventilation duct

6 5 green Sample 7 Shoe base

7 5 WhiteSample 9 Rubbish bin 7 5 Green

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Teacher may first ask students to comment on data and observation (as many points as they can think of). If necessary, teacher may use the following questions to guide the students to think more deeply about the findings:

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Can we say the kind of mold in sample 5 grows faster than molds of other samples? Please explain your answer.

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Why is there odor from the bread? What is the cause? What is the component of the odor?

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Plain breadSample Treatment

of sample

No. of Days for mold to appear

No. of Days for odor to appear

Colour of fungus

Control sample 2 7 5 green, blue

Sample 2 Soil

4 5

Yellow, BlackBlue,green, white

Sample 4 Spoiled food6 4

White, Blue

Sample 6 Ventilation duct 6 5 blue

Sample 8 Shoe base

4 5

Green, BlackBlue, GreenWhite

Sample 10 Rubbish bin --- 5 ---

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Teacher may ask students what they can infer from the different colour spots observed in different samples [e.g. students may tell there are different kinds of mold in different places; different types of molds would grow at different rate in different bread (medium); the soil and shoe base contain the greatest varieties of molds, etc.

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Teacher may ask students their comments on the absence of mold but the detection of odor from sample 10. [What does the odor come from? Activities of bacteria?]

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Results• Sample 2 and Sample 8 became dry and

hard after the seven day experiment as water is absorbed by the mold.

• The white and yellow mold grew through spreading and do not have a regular shape, while mold of other colors (Black, blue, green, yellow, etc.) are spots.

Different Kinds of Fungi in the samples

Sample Type of Fungus Control Sample (1-2) Aspergillus oryzae

Sample 1 & 2 (soil)Aspergillus clavatus , Acremonium sp. AndCladosporium

Sample 3 & 4 (spoiled food) Aspergillus flavusSample 5 & 6 (ventilation duct) Aspergillus penicilloides

Sample 7 & 8 (shoe base) Aspergillus clavatus and Cladosporium

Sample 9 & 10 (rubbish bin) Rhizopus

The growth of mold in seven days

Sample No. Day1 Day2 Day3 Day4 Day5 Day6 Day7

Control Sample 1

White

A green spotControl Sample 2

A blue spot

WhiteSample 1

A green spot

Black White

Blue A blue spot

Sample 3 Yellow Spread of yellow mold

The yellow mold became deeper in color

Little orange spots

White( more)Sample 4 White( small amounts)

Blue spots

Sample 5 A green spot

The green spot became larger

Green spot

Sample 6 A blue spot Blue spots

Sample 7 White( small amounts)

White Yellow

Blue spots Green spots

Black spots

Sample 9 Green (not a spot)

Sample 10 No observable change

Sample 8 Black spots

Mold appeared at the back of the sample( a green and a blue spot)

Sample 2 Yellow

Sweet bread Plain bread

Treatment of sample

Colour of fungus Colour of fungus

Nil White green, blueSoil

green, whiteYellow, Black

Blue, green, white

Spoiled food Yellow, orange White, Blue Ventilation

duct green blue

Shoe baseWhite

Green, BlackBlue, green, white

Rubbish bin Green ---

Sample Type of Fungus Control Sample (1-2) Aspergillus oryzae

Sample 1 & 2 (soil)Aspergillus clavatus , Acremonium sp. AndCladosporium

Sample 3 & 4 (spoilt food) aspergillus flavusSample 5 & 6 (ventilation duct) Aspergillus penicilloides

Sample 7 & 8 (shoe base) Aspergillus clavatus and Cladosporium

Sample 9 & 10 (rubbish bin) Rhizopus

Analysis

• Different colors of moulds represents different species of fungi. From the above table, we can see that

• more species of fungi grow on plain bread when other conditions remain the same.

• more species of fungi grow when soil is scraped onto the bread

Analysis

• Soil contains the largest number of fungi species( including Aspergillusclavatus , Acremonium sp. and Cladosporium ) when comparing with the other four conditions.

Sweet bread and plain bread

The plain bread provides a better medium than sweet bread for the growth of microbes.

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Teacher may ask students to discuss further on the proposed reason for the more varieties of molds grown on sweet bread [what are the chemical nature of sweet bread? What can sugar provide to the molds to speed up their growth? What do molds need for growth?]

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Different Conditions

• Soil provides the best living condition for the growth of miscrobes of the five conditions we tested (Soil, spoiled food, ventilation duct, shoe base and rubbish bin)

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What are the implication of the findings? [Hygiene concern]

Links• http://www.moldremoval.com/html/m

old_types.htm• http://home.pacific.net.hk/~ppleung/

Chem/common%20mould%20on%20bread.htm

• http://en.wikipedia.org/wiki/Mold

http://www.moldremoval.com/html/mold_types.htm

http://www.moldremoval.com/html/mold_types.htm

http://en.wikipedia.org/wiki/Mold

study of growth of mold (students presentation) · 2018-05-10 · study of growth of mold...

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