Bacteria can cause disease in organisms by directly damaging tissues or releasing toxins. Common diseases caused by bacteria include tooth decay, Lyme disease, tetanus, tuberculosis, and pneumonia. Antibiotics can block bacterial growth and reproduction. Controlling bacteria involves sterilization, disinfectants, refrigeration, and cooking. Some bacteria are helpful by fixing nitrogen in soil, breaking down organic matter, producing flavors and antibiotics, assisting waste treatment, and providing vitamins. Bacteria reproduce through binary fission or conjugation.

1. Bacteria and Disease
• A pathogen is a disease-causing
agent.
• Bacteria can damage the tissues
of the affected organism directly
or release toxins that harm the
body.

2. Antibiotics
• Compounds that block the
growth and reproduction of
bacteria.
• Examples: penicillin &
tetracycline

3. Common Diseases Caused by
Bacteria
Disease Pathogen Prevention
Tooth decay Streptococcus mutans Regular dental hygiene
Lyme disease Borrelia burgdorferi Protection from tick bites
Tetanus Clostridium tetani Current tetanus vaccination
Tuberculosis Mycobacterium tuberculosis Vaccination
Salmonella food poisoning Salmonella enteritidis Proper food-handling practices
Pneumonia Streptococcus pneumoniae Maintaining good health
Cholera Vibrio cholerae Clean water supplies

4. Controlling Bacteria
• Sterilization – destroys bacteria
by subjecting them either to great
heat or chemical action.
• Disinfectants are chemical solutions
that kill bacteria.

5. Controlling Bacteria
• Food is refrigerated because
bacteria grow slower at low
temperatures.
• Food can be sterilized by cooking at
high temperatures.

6. Helpful Bacteria:
Nitrogen fixation
(Nitrogen Cycle)
convert nitrogen gas into nitrates in
the soil used by plants

7. Helpful Bacteria
Saprobes:
break down dead organic matter
(decomposers)
Food flavorings:
produced by fermentation
vinegar, yogurt, cheese, sour
cream, pickles, sauerkraut

8. Antibiotic production:
some bacteria produce antibiotics
that will kill other forms of
bacteria
Bioremediation –
help clean-up oil spills
Works in Landfills to break down
wastes (including some hazardous
wastes)
Waste- water treatment plants

9. Helpful Bacteria
• Provide Vitamin K (E coli)- clots
blood & keeps bones strong
• Keep invading bacteria, viruses,
& yeast in check.
• Make Lactase-enzyme needed to
break down dairy products

10. Bacteria Reproduction
• Binary fission – asexual
reproduction. The prokaryote
replicates DNA and divides in half.
(Mitosis)

11. • Conjugation – sexual reproduction.
A hollow bridge forms between two
cells and genes move from one cell to
another. (Increases diversity.)