Bacteria
Bacteria (Monerans)– Kingdoms
Archaebacteria and Eubacteria
• There are more bacteria on Earth than stars in the
sky!
• The closest estimate is that there are 5 million
trillion trillion bacteria on Earth – that’s a 5 with
30 zeroes after it.
• Bacteria produce the air we breathe, clean the
water we drink, and create fertile soil.
• Less than one percent of bacteria cause diseases.
Bacteria structure –
prokaryotic cell
plasmid
Bacteria Growth Curve
Most bacteria die when
conditions get bad:
• These conditions could be a change in
temperature, loss of food, change in pH, etc.
• Some bacteria can preserve themselves during bad
times, then they can regrow and resume their lives.
They do this by producing an endospore.
• Endospores can preserve the cell’s DNA until
conditions get better again. They are resistant to
all the bad conditions.
Endospore production – preserves the cell
during hard times– not a form of
reproduction
• Steps in formation of an endospore
Endospore
Bacteria that are
harmful to humans and
that form endospores:
Clostridium tetani –
causes tetanus
Clostridium botulinum –
causes food deadly
poisoning
Binary Fission – bacteria
can divide as often as
every 20 minutes!
Origin of Monerans
• Archaebacteria
– usually found in harsh
environments – hot, salty, smelly!
– Ancient – probably resemble the
first bacteria
Methanogens
• produce methane – live in digestive
tract of mammals, in swamps and
sewage.
thermophiles
• can live in extremely hot water –
found in hot springs
halophiles
• Live in very salty water, such as
the Great Salt Lake in Utah and
the Dead Sea
Eubacteria – true
bacteria
• Many types – modern bacteria
• Classification is by:
–
–
–
–
Cell shape
Cell wall composition
Nutrition
Respiration
Cell Shape
Coccus - round
Bacillus - rod
spirillum
Names can tell a lot about
the bacterial growth
• Some bacteria grow alone
• Diplo…means two
– Diplococcus
– Diplobacillus
• Strepto… means chain
- as in streptococcus
- and streptobacillus
•Staphylo… means cluster
•As in staphlyococcus
or
Cell Wall Composition – gram
positive or gram negative
• Gram Positive
Gram negative
• Stains blue
stains pink
Nutrition – Autotrophic
or Heterotrophic
• Autotrophs –
– make their own food
– Use sun’s energy or chemical energy
Most Monerans are
Heterotrophs
Escherichia coli
spirillum
anthrax
Respiration – process of
getting energy from food
Aerobic
» Need oxygen
» Can’t live without oxygen = obligate aerobes
» EX – TUBERCULOSIS BACTERIUM
Tb lung
» Prefers to live with oxygen = facultative
aerobes
• Anaerobic –
– don’t need oxYgen
– SOME CAN’T SURVIVE WITH OXYGEN –
THESE ARE OBLIGATE ANAEROBES
EX – TETANUS
This baby probably got tetanus from
honey – don’t give honey to a baby!
SOME CAN LIVE WITH OXYGEN BUT PREFER TO
LIVE WITHOUT IT – fACULTATIVE
ANAEROBES
E. coli
How Important are
bacteria to the world?
• Decomposition – most important
function for living things. What
happens to all the dead bodies?
• Here is a bacterium
of decay
Food web
Nitrogen cycle
Cow Digestion
Bacteria in the
stomach
Tooth Decay
Don’t forget to brush and floss your teeth!
Foods from bacteria
cheese
yogurt
sauerkraut
What conditions do bacteria need
for the best growth?
1. Food source (your soup is good)
2. Proper temperature - human
pathogens (disease causers) live best
at 98.6 F.
3. Moisture
4. Oxygen (aerobes) or not (anaerobes)
Change any of these and the growth of
bacteria can be slowed down or
stopped.
We compete with bacteria for our
food – they eat the same stuff we
do…. How do we preserve our
food?
Drying (prunes)
salting
refrigeration
freezing
pickling
Diseases caused by bacteria
Anthrax – a natural pathogen that can be used for
bioterrorism
Lyme disease – causes illness
and can lead to arthritis
plague
gonorrhea
Strep throat
Food poisoning
Salmonella food poisoning
– from eggs, chicken,
mayonnaise
Botulism –
from
improperly
canned foods
Antibiotics, if used cautiously,
can cure bacterial infections
Antibiotics are tested using Petri
dishes and paper soaked in the
antibiotic – anywhere the antibiotic
inhibits growth, a zone of inhibition
will be seen Most effective
Not effective
Here is a white blood cell
attacking a bacillus
bacillus
Uses of bacteria other
than food production
• Bioremediation – using
microorganisms to rid environment
of harmful substances
– Ex – oil spill site
– Hazardous waste site
– Sewage treatment
Medical uses of bacteria
• Genetic engineering to produce medical
products –
– Insulin
– Human growth hormone
Gene for human insulin or hgh
Now all cells will have the gene and
will make the product
That’s all folks!