Household Cleaning Products Effects On Yeast Survivorship

Jack LeechPittsburgh Central Catholic

High SchoolGrade 10

Ammonia• Common chemical used in cleaning

products and fertilizers.• In small amounts, ammonia can cause eye

and skin irritation. • In more concentrated amounts, ammonia

can cause severe skin burns. It can also lead to permanent lung damage if inhaled or blindness if it comes into direct contact with the eyes.

Bleach

• Widely used household cleaning product.

• Bleach can also cause skin burns and eye irritation.

• One of the most harmful effect of bleach is its tendency to react with other cleaning products (ammonia or vinegar) to form lethal gases and byproducts.

Organic Product: Seventh Generation

• Well-known for providing organic, environmentally safe products for over 18 years.

• Claims to be non-toxic, hypo-allergenic, emits no fumes, and contains no phosphates.

• Only listed harmful effect is possible eye irritant resulting from direct contact with the solution on the eye.

Why were these variables used?

• Known to have some kind of negative effect on living cells.

• Now these results will be compared to an organic product and its effect.

Why is Yeast the Test Subject?

• Cell used was a species of yeast known as Saccharomyces cerevisiae.

• Easy to manipulate in the laboratory.• Very similar in structure to human cells. • In addition, this cell is a eukaryotic cell but

buds in single colonies, so they can be easily counted.

Purpose:

• Discover if any household cleaning products have a significant effect on the growth of yeast colonies.

• If the cleaning products have an effect on the yeast growth, which has the greatest effect; ammonia, bleach, or the organic product.

Hypothesis

• Null-the cleaning products will have no significant effect on yeast survivorship.

• Alternative-based on the numerous negative effects that the products can cause, ammonia will have the greatest effect on the yeast growth, followed by bleach and finally Seventh Generation.

Materials

• 42 YEPD agar plates (1% yeast extract, 2% glucose, 1.5% agar)

• YEPD media (1% yeast extract, 2% peptone, 2% glucose)• Sterile capped test tube sterile dilution fluid (SDF) (10 mM

KH2PO4, 10 mM K2HPO4, 1 mM MgSO4, 0.1 mM CaCl2, 100 mM NaCl)

• Ammonia• Chlorine bleach• Seventh Generation disinfectant spray• Micropipette• Permanent marker• Plate spreader• Ethanol

Procedure (Indirect Exposure)• S.c. yeast was grown overnight in sterile YEPD media.• A sample of the overnight culture was added to fresh media in a

sterile sidearm flask.• The culture was placed in a shaking water bath (30 C) until a

density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 107 cells/mL.

• The plates were labeled and placed over the cleaning products fumes for intervals of 1 minute and 2 minutes.

• After vortexing to evenly suspend cells, 0.1mL aliquots were removed from the tubes and spread on 18 plates.

• The cell culture was diluted in sterile dilution fluid to a concentration of approximately 10 3 cells/mL.

• The plates were incubates at 30 C for 48 hours.• The resulting colonies were counted. Each colony is assumed to

have risen from one cell.

Procedure (Direct Exposure)• S.c. yeast was grown overnight in sterile YEPD media.• A sample of the overnight culture was added to fresh media in a

sterile sidearm flask.• The culture was placed in a shaking water bath (30 C) until a

density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 107 cells/mL.

• The cell culture was diluted in sterile dilution fluid to a concentration of approximately 10 3 cells/mL.

• After vortexing to evenly suspend cells, 0.1mL aliquots were removed from the tubes and spread on 18 plates.

• The plates were labeled and placed over the cleaning products fumes for intervals of 1 minute and 2 minutes.

• The plates were incubates at 30 C for 48 hours.• The resulting colonies were counted. Each colony is assumed to

have risen from one cell.

Yeast Survivorship of the Indirect Exposure

Time Exposed to Fumes

Resulting Colonies

p=0.03 p=0.27

p=

0.0

19 p

=0

.24

3

p=

0.7

07

p=

0.0

07

p=

0.9

36

p=

0.7

43

Yeast Survivorship of the Direct Exposure

Resulting Colonies

Time Exposed to Fumes

p=0.002 p=0.006

p=

7.7

9 *

10

-6

p=

2.3

2 *

10-5

p=

0.2

29

p=

1.9

6 *

10

-6

p=

.00

02

p=

0.1

89

Fumes of Cleaning Products

Ammonia

Seventh Generation

Bleach

Results

P-value( .019) < .05 (Significant effect on control)

P-value( .243) > .05 (Insufficient data to confirm an effect on control)

P-value( .707) > .05 (Significant effect on control)

Ammonia

Bleach

Seventh Generation

P-value( .007) < .05 (Significant effect on control)

P-value( .936) > .05 (Insufficient data to confirm an effect on control)

P-value( .743) > .05 (Insufficient data to confirm an effect on control)

Ind

ire

ct 1

min

. exp

osu

reIn

dir

ect

2 m

in. e

xpo

sure

Fumes of Cleaning Products

Ammonia

Seventh Generation

Bleach

Results

P-value (7.79 * 10-6) < .05 (Significant effect on control)

P-value( 2.23 * 10 -5) < .05 (Significant effect on control)

P-value( .229) > .05 (Insufficient data to confirm an effect on control)

Ammonia

Bleach

Seventh Generation

P-value( 1.96 * 10-6) < .05 (Significant effect on control)

P-value( .0002) < .05 (Significant effect on control)

P-value( .189) > .05 (Significant effect on control)

Dir

ect

1 m

in. e

xpo

sure

Dir

ect

2 m

in. e

xpo

sure

What Does This Mean?

• Direct exposure had a much more destructive effect on the yeast survivorship.

• Time exposed had little to do with the indirect exposure, but the time exposed did effect the direct exposure.

Conclusions• Null hypothesis partially rejected. • Sufficient evidence to see that the direct

exposure had a negative effect on the yeast cells; indirect exposure was not as effective.

• Based on the p-values of the variables compared to the control, ammonia was the most destructive source followed by chlorine bleach and Seventh Generation.

Conclusions (cont.)

• Indirect exposure did have some effect based on the cell count of the plates.

• Not enough to prove that it was the effect of the cleaning products fumes’ outside of chance.

• The most effective form of cell destruction resulted from the direct exposure.

Limitations in the Experiment

• Not exposing the yeast completely to the fumes.

• Environmental contamination could have been a factor.

• The plates were not vortexed between each trial.

Continuing the Experiment

• Use different kinds of fumes and expose to yeast.

• Test the separate ingredients of the product instead of the whole product.

Works Cited

• www.epa.gov

• www.sciencedirect.com

• www.bbc.co.uk

• www.seventhgeneration.org