The Impact of Microorganisms in

Life

Name: Putrie Amierra binti JaffarClass: 4 Suria

Teacher: Pn. Jamilah binti Suhaimi

Contents

IntroductionThe main essential of this folio is to broaden the students’ knowledge in Biology and not forgetting to enhance the

application of Biology in our daily lives. The topic, “The Impact of Microorganisms in Life” is simply appropriate as microorganisms

are part of our lives no matter where we are.

I did enjoy doing this folio as I find it as a better and more interesting way to understand Biology rather than a dull lesson in class. In particular, I’d like to thank Pn. Jamilah binti Suhaimi,

parents and friends, for their full support and cooperation. Also, a heartfelt thanks for those who have cooperated directly and

indirectly in making this folio a success.

Yours sincerely,

(Putrie Amierra)

Microorganisms

Microorganisms are tiny organisms that can only be seen clearly under a microscope

Most microorganisms are harmless and useful to humans while others can cause disease in plants and

animals, including humans

Microorganisms are divided into five types:

viruses bacteria

algae protozoa fungi

Types of Microorganisms

Bacteria

Bacteria are unicellular organisms which have a basic cell structure that includes a cell wall,

plasma membrane and DNA that is not enclosed in a membrane.

Bacteria cell walls are made up of a unique polymer called peptidoglycan

They form spores under unfavourable conditions

Bacteria are spherical (coccus), rod shaped (bacillus) or spiral shaped (spirillum)

Example of bacteria are Lactobacillus sp. and Staphylococcus sp.

Algae

Algae are photosynthetic, eukaryotic plant-like organisms

They are very simple organisms which contain chlorophyll

Their cell walls are made up of cellulose

They have no leaves, stems or roots

Most algae form spores

Example of algae are phytoplankton and spirogyra sp.

Fungi

Fungi are heterotrophic, multicellular eukaryotes which have no chlorophyll, stems, roots or leaves.

Fungal cell wall are made of chitin

Fungi feed by secreting enzymes that break down the surrounding organic material into simpler molecules before they are absorbed

Example of fungi are yeast and Mucor sp.

Protozoa

Protozoa are unicellular organisms

Protozoa have a nucleus, cytoplasm and a plasma membrane

They can carry life process such as respiration, reproduction and excretion

They move by flagella, cilia, or microtubules.

Example of protozoa are Euglena sp., Paramecium sp. and trypanosoma sp.

Viruses

A virus is the smallest microorganism and can only be seen under an electron microscope

A virus is a non living cell because it cannot survive or reproduce on its own outside the cells of its host

All viruses are infectious. They must infect living cells to reproduce. Since a virus does not have its own cellular

machinery, it must utilize the cellular machinery of the host to make copies of itself

Each type of virus has two basic parts; an inner core which is composed of nucleic acid, either DNA or RNA, and an outer capsid of protein sub-units

Viruses can be purified and crystallized. Example of viruses are T4 bacteriophage and tobacco mosaic virus

Bacteriophage are viruses that are parasites to bacteria while tobacco mosaic virus causes tobacco mosaic disease, so called because of the leaves’ mottled appearance

The Effects of Abiotic

Components on The Activity of

Microorganisms

Nutrients and Water

All microorganism except viruses need nutrients and water for growth and reproduction

Without nutrients or water, microorganism will die or form spores

PH

Most bacteria prefer slightly alkaline condition (pH 7.4)

Mould, yeast and protozoans prefer acidic condition (pH 4.5 – 5.0)

Each species of microorganisms has an optimum pH

Extreme pH will kill the microorganism

Temperature

Microorganism and their spores can only be destroyed when they are sterilized at a temperature of about 121°C

Beyond 60°C the growth of microorganism is inhibited

Most microorganisms are inactive in low temperature

The optimum temperature of most microorganism between 35 °C to 40°C

Microorganisms also prefer dark or low light intensities

High intensities of sunlight or ultraviolet rays can kill microorganisms

Light Intensity

However, photosynthetic algae and bacteria need light to carry out photosynthesis

Experiments

Aim: To study the effects of temperature, pH, light intensity and nutrients on the activity of yeast

(A) The effect of temperature on the activity of yeast

Problem statement: How does temperature affect yeast activity?

Hypothesis: The acitivity of yeast is optimum at a temperature of 35°C

Materials: Yeast suspension (4g of yeast in 100 cm³ of glucose solution) and coloured liquid

Apparatus: Boiling tubes, glass tubes, clips, rubber stoppers, rubber tubings, retort stands, manometer tubes, strings, measuring cylinders, stopwatches and thermometers.

Technique: Measuring the difference in the heights of coloured liquid in the manometer

Variables: Manipulated: Temperature Responding: height of coloured liquid in the manometer Fixed: Volume of yeast suspension, pH, light intensity and

time taken

Procedure:

1. Five boiling tubes are labeled A, B, C, D and E.2. The boiling tubes are filled with 15cm³ of yeast suspension.3. Five sets of apparatus are set up as shown in Figure 8.39.4. Test tube A is placed in a beaker of ice. The temperature is

recorded after 5 minutes.5. The stopwatch is started and the height of the coloured liquid

in the manometer is recorded after 10 minutes.6. The procedure is repeated by placing boiling tubes B, C, D and

E into water baths set at temperatures of 20°C, 30°C, 40°C and 50°C respectively.

7. The results obtained are recorded in a table8. A graph of the height of the coloured liquid in the manometer

against the temperature is plotted.

Results:

Test tube Temperature (°C)Height of the coloured

liquid in the manometer (cm)

A 0°C -0.4B 20°C 2.6C 30°C 4.0D 40°C 4.1E 50°C 2.5

* (graph)

Discussion:

1. In each boiling tube, the activity of yeast is shown by the foaming of the contents in the tube as well as the increased height of the coloured liquid. As the yeast respires, the carbon dioxide that is released causes the pressure in the boiling tube to rise and subsequently pushes the coloured liquid up the manometer.

2. As the temperature increases, the activity of the yeast increases until it reaches 35°C, which is the optimum temperature. Beyond the optimum temperature, any increase in temperature no longer increases the activity of the yeast. Instead, the yeast activity begins to decline.

3. At 50°C, the higher temperature impedes the activity of the yeast as the yeast’s enzymes are denatured.

Conclusion: The activity of yeast is optimal at a temperature of 35°C. The hypothesis is accepted.

(B) The effect of pH on the activity of yeast

Problem statement: How does pH affect yeast activity?

Hypothesis: The acitivity of yeast is optimum in an acidic condition

Materials: Yeast suspension (4g of yeast in 100 cm³ of glucose solution), distilled water, 0.1 mol dm-3 and 0.01 mol dm-3 hydrochloric acid solutions, 0.1 mol dm-3 and 0.01 mol dm-3 sodium hydroxide solutions and coloured liquid.

Apparatus: Boiling tubes, glass tubes, clips, rubber stoppers, rubber tubings, retort stands, manometer tubes, strings, and stopwatches.

Technique: Measuring the difference in the heights of coloured liquid in the manometer

Variables: Manipulated: pH Responding: height of coloured liquid in the manometer Fixed: Volume of yeast suspension, temperature, light

intensity and time taken

Procedure:

1. Five boiling tubes are labeled A, B, C, D and E.2. The following contents are added into test tubes A,B,C,D, and E

respectivelyA: 15 cm³ of yeast suspension + 4 drops of 0.1 mol dm-3 hydrochloric acidB: 15 cm³ of yeast suspension + 4 drops of 0.01 mol dm-3 hydrochloric acidC: 15 cm³ of yeast suspension + 4 drops of distilled waterE: 15 cm³ of yeast suspension + 4 drops of 0.01 mol dm-3 sodium hydroxide solution

3. The contents of test tubes A, B, C, D and E are shaken well. The pH values of the mixtures are determined by using pH papers.

4. Five sets of apparatus are set up as shown in Figure 8.39.5. The activity of yeast is observed and the height of the coloured

liquid in the manometer is measured after 10 minutes.6. All observations are recorded in a table.7. A graph of the height of the coloured liquid in the manometer

against the pH used is plotted.

Results:

Boiling tube pHHeight of the coloured

liquid in the manometer (cm)

A 5 3.0B 6 1.5C 7 0.5D 8 -0.5E 9 -1.0

* (graph)

Discussion:

1. The activity of yeast is higher in an acidic medium.2. The activity of yeast declines in an alkaline medium.

Conclusion: The activity of yeast is optimum in the acidic medium. The hypothesis is accepted.

(C) The effect of light intensity on the activity of yeast

Problem statement: How does intensity of light affect the activity of yeast?

Hypothesis: The acitivity of yeast is higher at a lower intensity of light

Materials: Yeast suspension (4g of yeast in 100 cm³ of glucose solution), and coloured liquid.

Apparatus: Boiling tubes, glass tubes, clips, rubber stoppers, rubber tubings, retort stands, manometer tubes, strings, and a lamp (60 W).

Technique: Measuring the difference in the heights of coloured liquid in the manometer

Variables: Manipulated: light intensity Responding: height of coloured liquid in the manometer Fixed: Volume of yeast suspension, temperature, pH and

time taken

Procedure:

1. Five boiling tubes are labeled A, B, C, D and E.2. Five sets of apparatus are set up as shown in Figure 8.39. the

boiling tubes are allowed to stand in a beaker of water at room temperature.

3. A light source (60W) is set up. A,B,C,D, and E are placed at a distance of 50cm, 40cm, 30cm, 20cm and 10cm from the light source respectively.

4. The activity of yeast is observed. The height of the coloured liquid in the manometer is measured and recorded after 10 minutes in a table.

5. A graph of the height of the coloured liquid in the manometer against the distance from the light source is plotted.

Results:

Boiling tubeDistance from the light (cm)

Light intensity (1/distance)

Height of the coloured liquid in

the manometer (cm)

A 50 0.020 2.5B 40 0.025 0.8C 30 0.033 0.5D 20 0.050 0.0E 10 0.100 -1.0

* (graph)

Discussion:

1. The results show that the further the boiling tubes are from the light source, the higher the height of the coloured liquid. This means the activity of yeast is higher when the intensity of light is lower.

2. Yeast does not need light for growth. In fact, exposure to ultraviolet rays kills the yeast.

Conclusion: The activity of yeast is higher at a lower intensity of light. The hypothesis is accepted.

(D) The effect of nutrients on the activity of yeast

Problem statement: How do nutrients affect yeast activity?

Hypothesis: The concentration of nutrients affects the activity of yeast

Materials: Dry yeast, 5% glucose solution, 10% glucose solution, 15% glucose solution and distilled water

Apparatus: Boiling tubes, glass tubes, clips, rubber stoppers, rubber tubings, retort stands, manometer tubes and strings

Technique: Measuring the difference in the heights of coloured liquid in the manometer

Variables:

Manipulated: concentration of nutrients Responding: Height of coloured liquid in the manometer Fixed: Volume of yeast suspension, pH, light intensity and

temperatureProcedure:

1. Four sets of apparatus are set up as shown in Figure 8.39.2. The boiling tubes are labeled A, B, C and D.3. Each boiling tube is filled with the following:

4. The four sets of apparatus are placed in a water bath at room temperature.

5. The activity of yeast is observed. The height of the coloured liquid in the manometer is measured after 10 minutes and recorded in a table.

6. A graph of the height of the coloured liquid in the manometer against the concentration of nutrients is plotted.

Results:

Test tubeConcentration of

glucose (%)

Height of the coloured liquid in the manometer

(cm)A 0.0 0.0B 5.0 0.5C 10.0 1.5D 15.0 2.8

* (graph)

Discussion:

A: 1 g of dry yeast + 20cm³ of distilled waterB: 1 g of dry yeast + 20cm³ of 5% glucose solutionC: 1 g of dry yeast + 20cm³ of 10% glucose solutionD: 1 g of dry yeast + 20cm³ of 15% glucose solution

1. The activity of yeast is higher when the concentration of nutrients is high.

2. The increase in the activity of yeast means more carbon dioxide is released and this increases the height of the coloured liquid in the manometer.

Conclusion: Nutrients are needed by the yeast for respiration. The higher the concentration of nutrients, the higher the activity of yeast. The hypothesis is accepted.

The Role of Useful Microorganisms in

the Ecosystem

Nitrogen Cycle

Reservoir of nitrogen in the atmosphere (N2)

Atmospheric fixation

Fertilizers (NH4 ), (NO3 )

+

Denitrifying bacteria

Dead organism animal waste

-

Decomposers (bacteria, fungi)

Ammonia (NH3)Ammonium (NH4)

Nitrites (NO2 )-

Nitrates (NO3 )-

Fixation by nitrogen fixing bacteria (legume root nodules)

Nitrosomonas sp.

Rhizobium sp.

Nitrobucter sp.

Decomposition

Alimentary Canal of Termites

Decomposers

Organisms that secrete digestive enzymes to break down organic matter and animal waste into simpler molecules

e.g: saprophytic bacteria, fungi

CO² H20 minerals

Organic molecules

These molecules can be used by autotrophs such as green plants

Digestive System in Humans

They secrete cellulose which is required by the termites to digest cellulose

Contains celluloseUnable to

produce enzyme cellulose to digest the cellulose

Populations of mutualistic protozoans such as Trichonympha sp. are present in the alimentary canal of termites

Useful symbiotic bacteria are found in the human colon.

The useful microorganisms synthesise vitamins B12 and K which are often deficient in the human diet

The Harmful Effects of Microorganisms

• Microorganisms enter the alimentary canal

• when a person eats contaminated food and drinks

• through the faeces of infected people

• from unwashed hands of infected people who touched the food

• Microorganisms enter the body through respiratory system

• droplet transmission - liquid droplet which contains viruses or bacteria can cause illnesses

• airborne transmission - pathogens change into spores from dried sputum and are transmitted by air

Food and water Airborne and

droplet transmission

Methods in the Transmission of Diseases

Vectors Direct contact

Some pathogens are transmitted by vectors such as mosquitoes and flies

Vectors are carries of diseases

A contagious disease can be spread by contact with an infected person or by using the personal items of the infected person

Some diseases are transmittable through sexual intercourse with an infected person

Pathogens Disease Method of transmission Signs and symptoms

Protozoa(Plasmodium sp.)

Malaria Vector: Anopheles sp. Mosquito

High fever, violent shivering and profuse sweating

Virus Dengue fever Vector: Aedes mosquito Fever with severe body pain and rashes over part of the body

Associated symptoms include severe headaches and vomiting

Bacterium (Vibrio cholerae)

Cholera A person may get cholera by drinking water or eating food contaminated with the cholera bacterium

In an epidemic, the source of the contamination is usually the faeces of an infected person

The disease can spread rapidly in areas with inadequate sewage treatment and improper treatment of drinking water

Profuse and watery diarrhoea, vomiting and leg cramps

Rapid loss of body fluids leads to dehydration and shock

Without treatment, death can occur within hours

Fungi Ringworm (tinea corporis)

Contagious and is spread through infected pets or through direct contact with infected individuals

Rashes on the body which look like red circular lesions with a scaly border. These infected areas may be itchy.

Bacteria related food poisoning is the most common, for example, Salmonella sp.

Food poisoning Contamination of cooked food and inappropriate handling and preparation of food

Contamination of cooked food occurs from contact with surfaces or utensils that were not properly washed after contact with raw food products such as fish and meat

Diarrhoea, nausea, chills, vomiting and fever within 12 to 24 hours

Human Immunodeficiency Virus (HIV)

Acquired Immune Deficiency Syndrome (AIDS)

By having unprotected sex with an infected partner

Through blood transfusion from an infected person

Transmission from a pregnant mother to an unborn child

Use of contaminated syringes, needles or other piercing

People with AIDS often suffer diseases from the lungs, brain, eyes and other vital organs along with debilitating weight loss and diarrhoea

instruments

Methods of controlling pathogens

AntibioticsVaccines

Antiseptics Disinfectants

Antibiotics such as penicillin and streptomycin are complex chemical substances produced by microorganisms which can kill other microorganisms such as bacteria and fungi or inhibit their growth

Vaccines are modified or weakened forms of viruses or suspensions of dead bacteria which are inoculated into the body to induce the production of antibodies.

E.g: Sabine vaccine, BCG

Antiseptics are applied on cuts and wounds to kill and inhibit the growth of microorganisms.

E.g: acriflavin and iodine solution

Disinfectants are solutions used to kill microorganisms on the surface of floors, buildings or furniture. They are also used to sterilise surgical equipment

E.g: phenol, formaldehyde and carbolic acid

The Use of Microorganisms in

Biotechnology

Uses Examples of microorganismsProduction of antibiotics, vaccines and hormones Antibiotics are obtained from microorganisms

Common antibiotics include streptomycin which is produced by Streptomyces sp.and penicillin which is produced by Penicillium chrysogenum. They are used to treat various infections.

An example of a vaccine produced commercially is the Sabine vaccine which is used to treat poliomyelitis

Genetically modified bacteria are also used to produce the hormone insulin on a large scale

Cleaning of oil spills Oil spills which occur at sea are the result of collisions between oil tankers and other ocean vessels

Instead of using chemicals which are usually harmful to marine life, spills can be cleaned by using genetically engineered bacteria

When sprayed in the surface of oil spills, these bacteria convert the oil into less harmful molecules which are environment friendly

Waste treatment Sewage is the waste matter from households and industries

It is rich in organic matter, bacteria and other microorganisms

Sewage from various households and industries is piped into large settling tanks in sewage treatment plants

During the waste treatment process, millions of aerobic bacteria present in the sewage decompose organic matter in the presence of oxygen

Most of the sludge that settles at the bottom of the settling

tanks is pumped into the sedimentation tanks where the fermentation takes place

Here, anaerobic bacteria continue to decompose the organic matter to methane and carbon dioxide, along with water and other minerals

The methane gas is collected and used as fuel for the engine pumps in the sewage plants

The digested sludge is rich in nitrates and phosphates and when it is dried it can be used as fertilizers by farmers

Food processing The commercial use of microorganisms in food processing is based on the process of fermentation

The main ingredients of bread are yeast, flour, sugar and water. The most commonly used species of yeast in bread making is Saccharomyces cerevisiae (baker’s yeast)

Beer is brewed from barley grains. In commercial beer-making, two commonly used yeast species are S. cerevisiae and S. carlsbergensis (brewer’s yeast)

Production of biodegradable plastic (bioplastic) Biodegradable plastic called bioplastic has been successfully produced

Bioplastic such as Biopol can be broken down into inorganic compounds by bacteria

Bioplastic is used to make credit cards and bottles. Some bioplastic is used to make medical gums

Production of energy from biomass Two sources of energy that are generated through activities of microorganisms are biogas and gasohol

Biogas is a gas produced by the anaerobic fermentation of organic matter or waste in a bioreactor. This gas is similar to a natural gas

Gasohol or biofuel is a combination of 10% ethanol and 90% petrol

.Appreciating Biodiversity

The Importance of Preservation and Conservation of Biodiversity

1. Organisms and ecosystems not only provide many useful products such as food, medicines and various industrial products for humans, but are also sites for recreational activities and research.

2. The possibility of identifying new products, for example, medicines to fight cancer, provides a strong case to conserve biodiversity.

3. In recent years, rapid development and human activities such as deforestation have not only disturbed the ecological equilibrium, but also lead to the extinction of many species of organism. This results in a loss of biodiversity.

4. To protect biodiversity, we need to conserve and

preserve.

The efforts made in maintaining the quality of the natural environments and their biological resources

These efforts strive to return an affected ecosystem to its natural equilibrium

E.g: replanting programmes are carried out after selective logging in a rainforest

The efforts in protecting the Earth’s diverse ecosystems and wildlife species which are threatened with extinction

Human interference in the ecosystems has to be minimized to ensure the survival of the maximum number of species and genetic diversity

Conservation Preservation