Study of growth of mold (Students Presentation) Objective To - - PowerPoint PPT Presentation

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 bread None Control sample 1 Control sample 2 Soil Sample 1 Sample 2 Spoiled food Sample 3 Sample 4 Ventilation duct Sample 5 Sample 6 Shoe base Sample 7 Sample 8 Rubbish bin Sample 9 Sample 10

Type of bread used Sweet bread Method of sampling Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample No Treatment of sample? In shaded area

Control sample 1 Day 7

White mold appeared.

Type of bread used plain bread Method of sampling Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample No Treatment of sample? In shaded area

Control Sample 2 Day 7

Mold appeared! A blue spot A green spot

Type of bread used Sweet bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample Soil Treatment of sample? In shaded area

Sample 1 Day 7

White mold White mold

A green spot White mold

Type of bread used Plain bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample Soil Treatment of sample? In shaded area

Sample 2 Day 4

Yellow mold

Sample 2 Day 5

Blue mould Black mould

Sample 2 Day 6

A blue spot White mould

Sample 2 Day 7

Front Back A green spot A blue spot

Sample 2

• became dry and hard after the

seven-day experiment as water is absorbed by the mold.

Type of bread used Sweet bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample Spoiled food Treatment of sample? In shaded area

Sample 3 Day 2

Yellow mold

Sample 3 Day 3

The yellow mold spread.

Sample 3 Day 6

The yellow mold became deeper in color.

Sample 3 Day 7

Little orange spots New mold appeared!

Type of bread used plain bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample Spoiled food Treatment of sample? In shaded area

Sample 4 Day 6

White mold( small amounts)

Sample 4 Day 7

Blue spots White mold

Type of bread used Sweet bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample ventilation duct Treatment of sample? In shaded area

Sample 5 Day 5

A green spot mold appeared

Sample 5 Day 6

The green spot became larger

Sample 5 Day 7

Mold becomes larger.

Type of bread used plain bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample ventilation duct Treatment of sample? In shaded area

Sample 6 Day 6

A blue spot Mold appeared!

Type of bread used Sweet bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample Shoe base Treatment of sample? In shaded area

Sample 7 Day 7

White mold( small amounts)

Type of bread used plain bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag

• pened a quarter

Place we collected the sample Shoe base Treatment of sample? In shaded area

Sample 8 Day 3

Mold appeared! Black spots

Sample 8 Day 6

Black spots Blue spots White mold More mold appeared.

Sample 8 Day 7

Green spots Blue spots

Sample 8

• became dry and hard after the

seven-day experiment as water is absorbed by the mold.

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?]

Type of bread used Sweet bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag

• pened a quarter

Place we collected the sample rubbish bin Treatment of sample? In shaded area

Sample 9 Day 7

Green mold

Type of bread used plain bread Method of sampling scraping Any moisture added? Water Ventilation With the zip bag opened a quarter Place we collected the sample rubbish bin Treatment of sample? In shaded area

Sample 10 Day 7

Remains unchanged.

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.

Results

Sweet bread Sample Treatment of sample

• No. of Days for

mold to appear

• No. of Days for
• dor to

appear Colour of fungus Control sample 1 7 5 White Sample 1 Soil 7 5 green, white Sample 3 Spoiled food 7 4 Yellow, orange Sample 5 Ventilation duct 6 5 green Sample 7 Shoe base 7 5 White Sample 9 Rubbish bin 7 5 Green

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: Can we say the kind of mold in sample 5 grows faster than molds of other samples? Please explain your answer. Why is there odor from the bread? What is the cause? What is the component of the odor?

Plain bread Sample Treatment

• f

sample

• No. of Days for

mold to appear

• No. of Days for
• dor to appear

Colour of fungus Control sample 2 7 5 green, blue Sample 2 Soil 4 5 Yellow, Black Blue,green, white Sample 4 Spoiled food 6 4 White, Blue Sample 6 Ventilation duct 6 5 blue Sample 8 Shoe base 4 5 Green, Black Blue, Green White Sample 10 Rubbish bin

• 5
• 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. 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?]

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. And Cladosporium Sample 3 & 4 (spoiled food) Aspergillus flavus Sample 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 spot Control Sample 2 A blue spot White Sample 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

• f sample

Colour of fungus Colour of fungus Nil White green, blue Soil green, white Yellow, Black Blue, green, white Spoiled food Yellow, orange White, Blue Ventilation duct green blue Shoe base White Green, Black Blue, green, white Rubbish bin Green

Sample Type of Fungus Control Sample (1-2) Aspergillus oryzae Sample 1 & 2 (soil) Aspergillus clavatus , Acremonium sp. And Cladosporium Sample 3 & 4 (spoilt food) aspergillus flavus Sample 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 Aspergillus

clavatus , 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.

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?]

Different Conditions

• Soil provides the best living

condition for the growth of miscrobes

• f the five conditions

we tested (Soil, spoiled food, ventilation

duct, shoe base and rubbish bin)

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

Links

• http://www.moldremoval.com/html/m
• ld_types.htm
• http://home.pacific.net.hk/~ppleung/

Chem/common%20mould%20on%20br ead.htm

• http://en.wikipedia.org/wiki/Mold