1. Part II Bacteria, and Viruses
Microbiology
Part II Bacteria, and Viruses

2. Bacteria There are two main types of Bacteria
Eubacteria “true bacteria” are found everywhere, in the air, on the ground, and in water, even on the page you’re writing now.
Archebacteria “ancient bacteria” are found only in extreme environments, for example, places that are intensely hot (sulfur pools, ocean vents), salty (Dead Sea), or acidic (inside digestive tract).

3. Bacteria Most Bacteria are much smaller than plant and animal cells.
They are Prokaryotic cells. This means they have no nucleus… all the genetic material is just strewn around loose in the cell.
Bacteria do contain ribosomes to manufacture protein.

4. Bacteria
Some bacteria also contain the pigment chlorophyll and are autotrophs, able to produce their own food through photosynthesis.
Some other autotrophic bacteria can use energy from chemicals in their environment to produce their food (chemosynthesis).
Most, however, are heterotrophs, consuming a variety of foods, breaking down dead material or living as parasites off a host.

5. Bacteria in soil
Bacteria
Almost all organisms on earth including most bacteria require oxygen to break down food and release energy- they are called aerobic organisms.
Some bacteria, however, are adapted to live completely without oxygen and are called anaerobic. These are usually found buried deep in muddy swamps or bogs, in hydrothermal vents in the ocean, or even in the human intestine!
Intestinal bacteria

6. Bacteria in Nature and Industry
Bacteria are involved in:
Oxygen and food production
Environmental recycling and cleanup
In health maintenance and medicine production

7. Bacteria in Nature and Industry: Oxygen Production
Autotrophic bacteria use the sun's energy to produce their food and as a result they release oxygen into the air.
Scientists believe autotrophic bacteria were responsible for adding oxygen to the Earth's early atmosphere and made it habitable for life as we know it.
Today, distant ancestors of those bacteria continue to keep oxygen levels in the air stable

8. Bacteria in Nature and Industry: Food Production
The activities of helpful bacteria help produce many foods, like soy sauce, sauerkraut, pickles, apple cider and vinegar.
Bacteria that grow in milk help produce dairy products such as buttermilk, yogurt, sour cream and cheeses.

9. Bacteria in Nature and Industry: Food Production
Some bacteria, however cause food to spoil when they break down the food's chemicals.
Refrigeration and heating can slow down spoilage
Another method to preserve food is called pasteurization
Named after its inventor, Louis Pasteur, it involves heating food to a temperature high enough to kill harmful bacteria without changing the flavor of the food.

10. Bacteria in Nature and Industry: Environmental Recycling
Some heterotrophic bacteria that live in soil are decomposers, -organisms that break down large chemicals in dead organisms into smaller chemicals
For example, decomposing dead leaves in the fall and winter so the nutrients can be re-used by the plants in the spring

11. Bacteria in Nature and Industry: Environmental Recycling
Nitrogen-fixing bacteria live in the soil and in nodules in the roots of a type of plant called a legume (like peanuts, soy beans and peas)
These helpful bacteria help plants by converting nitrogen from the air into a form of nitrogen plants need to survive.
Without nitrogen-fixing bacteria, farmers would need to spend millions more on fertilizer each year.

12. Bacteria in Nature and Industry: Bio-remediation (Environmental Clean-up)
Some bacteria can digest oils.
They can convert the poisonous chemicals in oil into harmless substances.
Scientists use them to help clean-up oil spills in oceans and gasoline leaks in soil under gas stations.

13. Bacteria and your health: Natural Flora Bacteria
There are many bacteria in your body that help keep you healthy
In your digestive system your intestines teem with bacteria.
Some help you digest food
Some make vitamins like vitamin K that your body needs
Others compete for space and resources with disease causing organisms, keeping harmful bacteria from attaching to your intestines, making you sick.

14. Viruses
A virus is a tiny non-living particle that enters and then reproduces inside a living cell.
No organisms are safe from viruses,
For every different type of cell in every different type of organism, there is a virus able to invade that organism's cells.

15. Viruses: Characteristics
Viruses come in many shapes
All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material
Some viruses are surrounded by an additional covering called an envelope

16. Viruses: Characteristics
Each virus contains specific surface proteins.
They are shaped to match a particular host cell
This explains why each virus has very specific host cells that it is able to infect.

17. Viruses: How they multiply
Viruses are considered non-living because they do not show all the characteristics of life.
They are not cells and do not use their own energy to grow or respond to their environment
Although viruses can multiply, they do so differently than organisms. Viruses can multiply only inside a living host cell
A virus acts like a parasite, as almost all viruses destroy the cells in which they multiply.

18. Viruses: How they multiply
Once inside a host cell, a virus's genetic material takes over many of the cells functions.
It instructs a cell to produce the virus's proteins genetic material.
These then assemble into new viruses ready to infect more host cells.

19. Viruses: How they multiply
Active viruses begin production, and assembly immediately.
Making copy after copy of the viruses until the host cell bursts open and new viruses begin infecting neighboring cells.

20. Viruses: How they multiply
Hidden or latent viruses do not affect the cell right away.
The virus genetic material becomes part of the cell's genetic material.
Each time the host cell divides, the virus genetic material is copied along with the host material.
Then under certain circumstances, the virus's genetic material suddenly becomes active and all of the damaged cells begin producing copies of the virus.

21. Viruses in medicine Not all news about viruses is bad.
Gene Therapy takes advantage of a virus's ability to enter a host cell
Scientists replace harmful virus genetic material with good genetic material
They then use the virus as a messenger service to deliver genetic material to cells that need it.

22. Bacteria, Viruses and your health
How Infectious diseases are spread:
Through contact with an infected person
A contaminated object
An infected animal
An environmental source.
Once contact occurs disease-causing agents may enter through:
Breaks in the skin
May be inhaled or swallowed
May enter the moist linings of the eyes, nose, mouth or other body openings.

23. Treating Infectious Diseases
Luckily, many bacterial diseases can be treated with antibiotics.
An Antibiotic is a chemical that will destroy bacteria (usually by weakening the cell wall causing the bacterial cells to burst) without harming a person's cells

24. Treating Infectious Diseases
Unfortunately, some bacteria are becoming resistant to antibiotics. As resistant bacteria survive and reproduce the number of resistant bacteria increases.
Today some bacterial diseases are becoming very difficult to treat.

25. Treating Infectious Diseases
Unlike bacterial diseases there are currently no medicines that cure viral infections.
There are many over-the-counter medicines that can help a person feel better
The best treatment for a virus is usually bed rest.

26. Treating Infectious Diseases
Although there is no cure for a virus, a vaccine may be able to prevent a person from getting sick in the first place.
A vaccine stimulates the production of chemicals that destroy specific viruses or bacteria.

27. Treating Infectious Diseases
A vaccine may be made from dead or altered viruses or bacteria. Therefore it will not cause a person to become sick.
Instead the vaccine will activate a person's natural defenses putting the body “on alert”.
So that if the virus or bacterium ever invades the body it is destroyed by antibodies before it can cause the disease.