1. Bacteria
Our invisible friends

2. Bacteria are prokaryotes
Pro – before
Karyon – nucleus
The simplest forms of life are prokaryotes.
Earth’s first cells were prokaryotes.

3. Lots of Them! Prokaryotes are Earth’s most abundant life forms.
They can survive in many environments.
They can get energy from many different sources.

4. Kingdoms Bacteria fall into two kingdoms: Archaebacteria (Archaea)
Eubacteria

5. Archaebacteria Archae = early or primitive
In fact archaebacteria have a more advanced structure than eubacteria and share characteristics with eukaryotes
Cell wall lacks peptidoglycan
Genes and enzymes behave more like Eukaryotes
Cells have three RNA polymerases like eukaryotes

6. Archaebacteria
Many Archaebacteria are often referred to as extremophiles. They have the unique ability to survive in environments where other organisms cannot survive.
These extreme environments are anaerobic (lacking oxygen) and are believed to resemble conditions that existed when life first evolved on earth, billions of years ago.

7. Archaebacteria Three major groups of archaebacteria include:
Methanogens – methane-producing organisms
Extreme Thermophiles – thrive in temperatures up to 110°C
Extreme Halophiles – thrive in very salty environments

8. Eubacteria True bacteria More primitive than archaebacteria
Cell wall made of peptidoglycan
Cells have only one RNA polymerase

9. Similarities Common characteristics of Archaebacteria and Eubacteria:
Cells are prokaryotic, all are single celled
Cells contain no membrane-bound organelles
Cells reproduce asexually by binary fission or sexually by conjugation

10. Eubacteria Classified by Shape
Cocci (ball-shaped)
Streptococcus mutans
Bacillus (rod-shaped)
Clostridium botulinum
Spirilli (spiral-shaped)
Treponema palladium

11. Eubacteria Classified by Shape

12. Reproduction & Growth
Asexual Reproduction – only one parent is involved
Binary Fission – simpler than mitosis.
Single stand of bacterial DNA replicates
This identical genetic material is transferred to each new cell
Bacterium produces a cross wall and divides into two identical cells

13. Binary Fission

14. Reproduction & Growth Sexual Reproduction – two parents involved
Not common in bacteria
Conjugation
Transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells
The recipient cell now has an altered set of characteristics, due to recombination of the DNA

15. Conjugation

16. Factors Influencing Bacterial Growth
Physical Factors:
Nutritional Requirements:
Temperature
Energy source
Oxygen
Carbon pH
Nitrogen
Osmosis
Water
Other Minerals
Organisms having complex nutritional requirements and needing many growth factors are said to be fastidious

17. Harmful Effects of Bacteria
Bacteria are best known for being:
pathogenic - disease causing.
The anthrax causing bacteria Bacillus anthracis was the first bacterium proven to cause disease.

18. Virulence Factors
Virulence factors are molecules expressed and secreted by bacteria that enable them to achieve the following:
Immunoevasion, evasion of the host's immune response
Immunosuppression, inhibition of the host’s immune response
Entry into and exit out of cells
Obtain nutrients from the host

19. Symptoms Bacteria cause disease in three major ways:
Their sheer numbers burden the host’s tissues and interfere with normal function
The bacteria cells destroy the hosts cells and tissues
Some bacteria produce poison called toxins which shut down the hosts tissues

20. Spread and Protection
Infectious bacterial diseases are spread from one individual to another in a variety of ways:
Moisture droplets in the air
Dust
Direct contact
Fecal contamination
Animal bites
wounds

21. Spread and Protection
Most people have built in protection provided by the body’s own defense mechanisms: Immune System
Other methods of protection include:
Sterilization/disinfection
Use of antiseptics
Extermination of animals that carry bacterial disease
Immunizations and administration of antibiotics

22. Examples of Pathogenic Bacteria
Type of Bacteria
Disease/destruction produced
cloasridia
botulism, tetanus, and gangrene
streptococci
strep throat, scarlet fever, and pneumonia
staphylococci
boils, food poisoning, and skin infections
lactobacilli
souring of milk
pseudomonads
gasoline spoilage
bacilli
destruction of silkworms
staphylococci and pseudomonads
food spoilage
coliform bacteria
Pollution of water sources, soft rot in plants, gastroenteritis and dysentery in humans
spirilla
cholera and syphilis

23. Bacteria: Friend or Foe?
The usefulness of bacteria far outweigh the damage they cause.
One of the most important jobs of bacteria are the recycling they do as decomposers.
Bacteria are the primary organism responsible for converting dead plants and animals into natures raw materials. These nutrients are essential for living plants and animals.

24. Beneficial Effects of Bacteria
Type of Bacteria
Beneficial Effects
clostridia
production of butanol and acetone from molasses
acetobacter
production of vinegar from alcohol
intestinal bacteria
food digestion; synthesizing of vitamins in humans
eg. To regulate blood clotting
lactobacilli
production of lactic acid form sugar
aztobacter, nitrobacter
fixation of nitrogen in soils
streptococci, lactobacilli
production of dairy products
eg. Cheese, buttermilk, and yogurt
streptomyces
source of antibiotics
eg. Streptomycin, terramycin, neomycin, and erythomycin

25. Bacteria Cleaning Crew
Some bacteria literally 'live on oil,' just as some people live on meat and potatoes. And they consume it with just as much relish.
Such bioremediation cannot only help to clean up oil spills, but also chlorinated chemicals and leaks from storage tanks.

26. Probiotics
Probiotics - live microorganisms that are healthy for the host organism
Lactic acid bacteria (LAB) and bifidobacteria are the most common types of microbes used as probiotics
Probiotics are commonly consumed as part of fermented foods including:
Yogurt Dietary Supplements
Buttermilk

27. Antibacterial Resistance
Over the past 50 years, many disease-causing bacteria have slowly developed resistance to antibiotics
This resistance arises due to variations within a bacterial population allowing for natural selection

28. Antibacterial Resistance
Bacteria resistant to antibiotics contain
R (resistance) Factors
These R factors are plasmids with special genes that code for enzymes which inactivate specific drugs
The R factors are transferred and recombined in conjugation
“The misuse of antibiotics could cause serious problems for society”