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The effect of nicotine, air, yeast on mold growth

The effect of nicotine, air, yeast on mold growth

Introduction: (Initial Observation)

Molds are a member of the fungi kingdom. Mold grows on any suitable environment, specially on foods. Bread mold is one of the commonly known types of mold. Mold will cause a bad taste on bread and certain types of mold are toxic. Many studies have been done that can help us to prevent or control the mold.

This project is an attempt to discover or identify additional methods that may be used to prevent mold.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.  

Project advisor

Importance: In the year 2001 the Insurance companies in United States paid out $1.2 billion in mold-related claims by homeowners. Mold cause a much larger damage in the form of product loss and property damage to businesses specially to manufacturers of food products. All food products, textile, paper and wood products are in constant risk for mold damage. Discovering methods of mold prevention can help reducing such damages.

Adult supervision and help is required in this project.

Information Gathering:

What are molds and how do they grow?

Molds are fungi, usually microscopic in size, that occur in nature in large quantities. They reproduce by releasing spores into the air that settle on surfaces and, under the right conditions, grow. Growths of mold can often be seen in the form of a discoloration, ranging from white to orange and green to brown and black.

Mold can sometimes be detected by its musty odor. Mil-dew is a common mold. When mold spores settle on organic or contaminated surfaces and when other conditions of temperature, humidity, shade or darkness, and oxygen supply are favorable , they germinate and develop new colonies of mold. Even surfaces from which mold has previously been removed can have mold growing again if the conditions are right.

What are the conditions that support mold growth?

Molds thrive on organic materials like natural fibers (such as cotton and wool), paper, leather, wood, or surfaces coated with the slightest amount of or-agonic matter such as food, grease, and soil. Molds that continue to grow can eventually eat away the organic medium that is their source of food. Wooden structural materials and textiles can deteriorate when mold is allowed to thrive on them.

Molds grow best in warm temperatures, 77 to 86 degrees Fahrenheit, though some growth may occur anywhere between 32 and 95 degrees.

Molds require moisture. Moisture can come from water leaks, flooding, capillary movement (wicking from one area to another), high relative humidity, and condensation. The moisture may be in the host material, on its surface, or in the form of humidity in the air. Relative humidity levels above 70 percent appear to be optimal for fungal or mold spore growth. A lower relative humidity level reduces the rate of mold growth as the mold goes dormant but does not stop growth and development entirely. In fact, at low relative humidity levels, there is increased spore release into the air.

Materials that are exposed to a constant leak or have been soaked and not dried thoroughly can support mold growth. Some molds can take hold and form a new colony in one or two days on damp materials. When the relative humidity is low, the temperature is too high or too low, or the organic material is gone, molds go dormant. But when the relative humidity gets high, they can regenerate.

Molds require oxygen, but not light, for growth.

Mold growth can continue indefinitely without light.

What are the health effects of exposure to mold?

We are all exposed to many kinds of mold both in-side and outside the house. However, some people seem to be more sensitive to mold and have allergies to some types of mold. These people may suffer from cold-like symptoms.

When people are experiencing these symptoms, it is difficult to know if they are the result of exposure to molds or have other causes. When breathed, some mold spores are small enough to go deeply into the lungs and cause serious illness. It is not healthy to live in a home with high levels of mold.

How do I know if there is mold in my house?

Many times, mold can be detected by a musty odor. Although mold spores are too small to be seen, colonies of mold growth are sometimes visible on damp walls and musty-smelling textiles. Mildew is one type of mold that can often be seen. In most cases, it is not practical to test for mold growth in a house. There are no standards for “accept-able” levels of mold in a dwelling, and when testing is done, it is usually to compare levels of mold spores inside the house with levels outside the house. It is generally better to look for mold in those places where conditions promote mold growth.

Where would mold be most likely to grow?

Generally, mold may be found anyplace where moisture or relative humidity levels are high. Wet or damp basements may have mold growing on the walls, floors, carpeting, or on materials stored in the basement.

Moisture from the earth can migrate through concrete walls causing them to remain damp. Water standing in sump holes, condensate from an air conditioner or dehumidifier, leaky pipes, or water seeping into the basement are all sources of moisture that can support mold growth.

Basement carpeting often has mold growing on or under it if the carpeting is installed on a concrete floor that remains cool and damp. Materials stored in a damp basement may have mold growing on them. In particular, firewood stored in the basement puts moisture into the air and is an excellent medium for mold growth. The mold spores can then spread throughout the house.

Crawlspaces built over uncovered earth can have mold problems when the moisture in the ground causes dampness in the space. Crawlspaces that are sloped incorrectly and have water pooling in them are particularly likely to have problems.

Mold can often be found growing in the bathroom.

If an exhaust fan is not used during bathing, large amounts of moisture can remain in the shower or tub area. Soap scum on bath and shower walls, even on ceramic tile or fiberglass, is a nutrient source for mold growth.

In the laundry room, unventilated clothes drying produces high levels of relative humidity that support mold growth. Damp towels and clothes in laundry hampers, washers, or dryers can develop mildew growth.

Using a humidifier sometimes raises the relative humidity high enough that mold will grow. Particularly in the winter, high relative humidity in areas where there is little air movement results in condensation on cold walls and subsequent mold growth. Dark patches of mold can sometimes be seen inside the upper corner of a closet on an outside wall or behind furniture placed against outside walls. Window condensation can result in mold growth where the moisture runs onto the sill or wood trim.

Mold growth can be found on kitchen walls if household cooking involves large amounts of boiling water and no exhaust fan is used. The cooking spatters and grease film on walls are the source of nutrients for the mold, combined with the high humidity levels in those areas. Floor-level pans that collect the condensate from automatic defrosting refrigerators often have mold growing in them.

New construction materials, such as new wooden wall studs and floor joists, drywall compound, and masonry materials emit moisture into the home while the construction components dry.

How can mold growth be controlled?

Two strategies help prevent mold growth: Keep it Clean, Keep it Dry

Where mold growth has already started or is likely to start because of contamination from flooding or other moisture problems, not only clean and dry the surfaces but add a third strategy: Disinfect It


Keep It Clean

Keep surfaces and household textiles clean because mold grows on materials contaminated with soil and grease. Use a grease-cutting solution of detergent and water to wash hard surfaces like walls and floors to remove organic material that supports mold growth.

Tri-sodium phosphate is an effective cleaner for removing grease. Commonly called TSP and highly alkaline, it can sometimes be found in paint and hardware stores for washing walls in preparation for painting. Precautions should be taken when using strong cleaners such as TSP: Wear rubber gloves, and avoid breathing the powder or getting it in the eyes.

Rinse with clear water to remove any cleaner residue. Dry quickly and thoroughly using fans and a dehumidifier, if possible.

Store textiles dry and clean. Dry soiled textiles can be kept for a few days before washing. Store clean textiles in a closet or container that discourages the growth of mildew.

Filtration of indoor air with an air cleaner can sometimes be effective in removing mold spores before they settle on damp surfaces and colonize. Some mold spores are large enough that standard furnace filters remove them. Some types of electro-static air cleaners also remove mold spores.

Keep It Dry

Reduce the moisture produced inside the home.

Discontinue using a humidifier if relative humidity levels are high (over 50%). Use exhaust fans vented to the outside when taking baths or showers or when cooking. Wipe down shower walls with a squeegee or sponge after bathing. Vent clothes dryers to the out-side. Do not use unvented kerosene or gas heaters. Repair all plumbing leaks. Do not store firewood inside the home.

Dehumidify humid areas. A dehumidifier, air conditioner, or furnace will help to dry the air. Increasing ventilation by opening windows or installing vents may help if relative humidity level is lower outside the house than inside. It is particularly important to dehumidify or ventilate the house when new construction materials have been added.

Increase the air flow in problem areas. Move furniture a few inches away from outside walls so that air flow will decrease the problem of condensation on the walls. If mold is growing in closets, keep closet doors open to promote air flow. Closets should not be over-filled, as this will reduce air circulation in the closet.

Louvered closet doors aid in ventilation. Circulating fans may help with air flow in problem areas.

Keep textiles dry. Always dry textiles that are damp or wet before storing, and do not store laundry in damp places. When cleaning textiles, follow the recommendations given on the care label. Quickly and thoroughly dry the products. Although plastic bags may be desirable to protect textiles for short periods of time, they should not be used for long-term storage because condensation may occur in the bag. Cloth bags or fabric, such as sheets, draped over stored textiles allow ventilation, provide protection from light and soil, and prevent condensation in storage.

Desiccants such as silica gel can be used in clothes storage areas to reduce moisture. Desiccants are more effective in small confined storage compartments such as drawers and boxes. Adequate ventilation, such as in closets with louvered doors or doors that are opened frequently, discourages mold growth as does leaving on a light in the closet.

Prevent condensation problems by installing ad-equate insulation to keep walls warm. Installing storm or thermal pane windows raises the temperature of the glass during winter months resulting in less condensation on windows.

Reduce sources of moisture coming in from the outside. Seal cracks in the basement walls and foundation. Slope the earth away from the house to pro-mote drainage away from the foundation walls. Use downspouts to direct rainwater away from the house. Cover window wells.

Install vapor barriers in crawlspaces to prevent ground moisture from entering. Crawlspaces that continue to have high humidity need ventilation.

Reference: http://www.oznet.ksu.edu/library/HOUS2/MF2141.PDF

Question/ Purpose:

The purpose of this project is to find out what are the effects of nicotine, air, and yeast on mold growth?

Since nicotine is a toxin, we want to see if it can prevent growing mold? For example we want to see if mold grows faster in a room with clean air or in a room with cigarette smoke?

Some breads are being packaged in air tight plastic bags. We want to see the effect of air on mold growth.

Finally yeast is being used in making some breads. We want to see if yeast can affect the mold growth.

Identify Variables:

Our variables are materials that may affect the mold growth. In this case they are yeast, air and nicotine.

(The effect can be prevention, delay, acceleration, decrease, or increase of mold growth.)


My hypothesis is that nicotine is a natural organic substance and will not affect the mold growth.

Air will be needed for mold to grow! That is why canned food does not mold until we open it.

Yeast will prevent or slow down the mold growth. Yeast will cause production of carbon dioxide and carbon dioxide is a preservative, so it should be able to prevent growing mold.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

To make sure that no other variable will affect our tests, we will make our own bread for the purpose of this experiment. You can find plenty of bread recipes in books and on the Internet. Select a simple recipe that uses wheat flour, water, yeast and salt.

Make about 60 pieces of small bread. (30 with yeast and 30 without yeast) and give them some time to cool off.

To test the effect of air:

1. Place 5 yeasted bread in 5 separate airtight zip lock plastic bags. Remove any extra air from the bag and close it. Number and label the bags.

2. Wrap 5 other yeasted bread in regular plastic bags. Number and label the bags.

3. Place 5 non-yeasted bread in one 5 separate airtight zip lock plastic bags. Remove any extra air from the bag and close it. Number and label the bags.

4. Wrap 5 other non-yeasted bread in regular plastic bags. Label the bags and paper towels. Number and label the bags.

Inspect the samples every day and record the results in the following table. Write what percentage* of the bread surface is covered by mold. Since you have 5 identical sample, if the amount of mold is not the same in all of those, take an average and enter it in the table.

Daily mold % table

No air exposure

Air exposure

Day 1



Day 2
Day 3

Record the results for 10 to 30 days.

* Percentage of surface covered by mold may be visually estimated. For more accurate estimate you may place a transparent grid paper on the bread and count the squares covering the bread and those that have mold on them.

To test the effect of nicotine (with yeast):

1. Place 5 yeasted bread in 5 separate plastic or glass jars with clean air. Cover the jars to prevent pollution.

2. Place 5 yeasted bread in 5 separate plastic or glass jars with cigarette smoke as a source of nicotine. Cover the jars to prevent additional pollution. To create cigarette smoke in a glass jar, light up a a cigarette and drop it in the jar. If you are using plastic bag, place the lit cigarette on a piece of aluminum foil so it will not burn the plastic. In either case the cigarette will turn off in a few seconds; however the remaining smoke will suffice your experiment purpose.

Inspect the samples every day and record the results in the following table. Write what percentage of the bread surface is covered by mold. Since you have 5 identical sample, if the amount of mold is not the same in all of those, take an average and enter it in the table.

Daily mold % table

No Nicotine exposure

Nicotine exposure

Day 1



Day 2
Day 3

Record the results for 10 to 30 days.

To test the effect of nicotine (without yeast):

1. Place 5 non-yeasted bread in 5 separate plastic or glass jars with clean air. Cover the jars to prevent pollution.

2. Place 5 non-yeasted bread in 5 separate plastic or glass jars with cigarette smoke as a source of nicotine. Cover the jars to prevent additional pollution.

Inspect the samples every day and record the results in the following table. Write what percentage of the bread surface is covered by mold. Since you have 5 identical sample, if the amount of mold is not the same in all of those, take an average and enter it in the table.

Daily mold % table

No Nicotine exposure

Nicotine exposure

Day 1
Day 2
Day 3

Record the results for 10 to 30 days.

Since we have repeated all experiments with yeast and without yeast, we can use the results to determine the effect of yeast on mold growth as well.

Materials and Equipment:

List of material can be extracted from the procedures. This is a sample:

  1. Bread (wheat flour, water, yeast and salt)
  2. Plastic bags
  3. Nicotine from cigarette smoke or tobacco. Instead of smoke you can soak these overnight and use the water that will contain dissolved nicotine.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.



Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

Does PH affect the mold growth?

Does moisture affect the mold growth?

Does temperature affect the mold growth?

Does light affect the mold growth?

Does salt affect the mold growth?

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.


List of References