Classification of Life

Aristotle

2 divisions: Plant and Animal

Linnaeus (1735-1759)

New division

Vermes

New category

Chaos (where microbes were placed)

Classification of Life

Ernst Haeckel (1866)

3 Kingdom System

Plantae, Animalia, and Protista

Robert Whittaker (1969)

5 Kingdom System

Plantae, Animalia, Protista, Fungi, Monera

Classification of Life

Carl Woese (1970s)

3 Domain System

Bacteria

Archaea

Eukarya

prokaryotic

commonalities of the 3 domains

• conduct glycolysis

• replicate DNA semiconservatively

• use same genetic code – DNA encodes polypeptides

• polypeptides produced by transcription and translation

• have phospholipid bi-layer plasma membranes and ribosomes

Kingdom: Monera

2 prokaryotic Domains:

Bacteria and Archaea

are

they

alive?

the monerans:

1000x smaller than most human cells

the most abundant kingdom - ubiquitous

Archaea

Prokaryotes

Extremophiles:

Thermophils

acidophiles

methanogens

Psychrophils

halophils

enzymes from these

organisms used in many

industrial applications.

Bacteria

Prokaryotes

Very diverse

NOT all bad!

# of good far outweigh

bad!

key characteristics for these domains: (differ from eukaryotes)

Lack a membrane-bound nucleus

DNA is double-stranded;

circular

lack membrane-bound organelles

Contain a full

compliment of

genetic and protein

synthesizing

systems:

DNA, RNA,

enzymes,

ribosomes and ATP

generation

Lack cytoskeleton

Without a cytoskeleton cannot replicate by mitosis

divide by fission

variety of metabolic life styles

anaerobic

pathways

lactic acid

alcohol

aerobic

pathways ATP

O2

No O2

obligate aerobes:

must have O2 to live (cellular respiration)

Mycobacterium tuberculosis

aerotolerant anaerobes:

not killed by O2 - but not used for

respiration

the aerobes

Lactobacillus acidophilus

obligate anaerobes:

must live in the absense of O2 (exposure to oxygen = death!)

facultative anaerobes:

can alter their metabolism and

live with/without O2

Clostridium botulism

Escherichia coli

the anaerobes

alternatives to oxygen

nitrogen fixers:

metabolize N2

some plants have developed

a symbiotic relationship with

bacteria which infect their

roots and, in return for sugars

from the plant, fix nitrogen

which can be used by the

plant for growth

sulfur metabolism

Astrophysicists and planetary scientists associated with NASA feel this

unique example of life in an extreme ecosystem (bacteria living within or

beneath a glacier and performing mineral transformation) may be a perfect

analogue to what life may look like on another planet.

Cell counts and DNA analyses

confirm that cold-loving bacteria

are living in the artic glacial ice.

Variety of nutritional systems:

produce their own food

photoautotrophs (true photosynthesis)

Use as source of E and CO2 as

source of C

chemoautotrophs

get E from chem. sources such as

ammonia, hydrogen, sulfur, etc., and

C from CO2

get their food from other sources

chemoheterotrophs photoheterotrophs

organic molecules are

sources for E and C Light is source for E,

organic compounds for C

most prokaryotes

prokaryotes are identified by:

shape

the way they

move how they

obtain

energy

cell wall

DNA

metabolism - energy

and

food

classified based on:

their source of Energy

whether or not they use oxygen for

respiration (or fermentation)

or

shape

bacilli - rod shaped

coccus - spherical

spirilla - spiral/corkscrew

Bacterial morphologies (1)

movement

sessile

flagella

“slime” secretions

cell wall

the cell wall

(capsule) is

composed of

petidoglycans

Some bacteria have thick and some have thin cell walls

Differences in cell wall component – indicator of differences in pathogenicity

Target of antibiotics – interferes with synthesis of peptidoglycans

Gram staining – combination of 2 stains: primary stain – violet

alcohol rinse (rinses away thin walls)

red counterstain

distinguished based on Gram staining

Gram+ bacteria

rod shaped anthrax bacteria in spinal fluid

thick cell walls

Gram bacteria

thin cell wall

Salmonella typhi

growth and reproduction

Could divide as quickly as every 20 minutes

…if a single bacteria divided unchecked every 20 min.,

in 48 hrs. the colony would reach a mass 4000X the

mass of earth!!!

growth is contained by:

of

reproduction is asexual

Binary fission

reproduction can include exchange of

genetic material

conjugation

transformation

reproductive preservation

spore formation

When growth

conditions are

unfavorable

Spores can lay

dormant for

years

BACTERIA in the environment

Serve as primary decomposers

Bacteria start the process of decaying

organic matter. They are the first to break

down plant tissue and also the most

numerous and effective

composters.

The most efficient decomposing bacteria thrive in

temperatures between 110 and 160 degrees F. Thus, the hotter the pile, the faster

the decomposing. (A 3' by 3' by 3' pile (1 cubic yard) is considered minimum size

for hot, fast composting.)

most are beneficial

Streptococcus lactis and other lactic

acid bacteria are used to make

cheese.

They ripen the cheese and provide

characteristic flavor.

Streptococcus thermophilus is

one of the major yogurt-

forming bacteria. The other is

Lactobacillus bulgaricus

beneficial

Used widely in the food industry (i.e., cheese making)

Used in sewage treatment to break down wastes

Produce antibiotics such as streptomycin

Feed on petroleum – clean

up oil spills and extract

metals from mining waste

Produce antibiotics such as

streptomycin

Feed on petroleum – clean

up oil spills and extract

metals from mining waste

some are pathogenic (disease causing)

Campylobacter jejuni is one of the major causes of diarrhea in humans Salmonella infection of

meat is one of the

major causes of food

poisoning

Listeria monocytogenes are

psychrotropic food pathogens

which can grow even in

refrigerated foods

pathogenic

Streptococcus pyogenes - flesh eating bacteria

Helicobacter pylori

stomach ulcers

Success as a pathogen depends on:

invasiveness toxigenicity

ability to multiply ability to produce chemical

toxins harmful to the host

Gram-positive cocci - Staphylococcus aureus (Figure 1) and Staphylococcus

epidermidis (Figure 2) together cause about half the ocular infections that occur in

humans

two types of bacterial toxins

endotoxins

Released by lysis of

Gram neg. bacteria.

Causes fever, vomiting

and diarrhea; rarely fatal

exotoxins

Proteins released by living

bacteria.

Highly toxic; often fatal;

usually no fever

E. coli 0157:H7

Bordetella pertussis

Corynebacteria diphtheriae are Gram-

positive, aerobic, nonmotile, rod-shaped

bacteria

Causal agent of Diphtheria

diphtheria as "an upper respiratory tract

illness characterized by sore throat, low-

grade fever, and an adherent membrane

of the tonsil(s), pharynx, and/or nose".

The diphtheria bacilli invade surface epithelial cells. At this site they produce the

toxin that is absorbed and disseminated through lymph channels and blood to

the susceptible tissues of the body. Degenerative changes in these tissues,

which include heart, muscle, peripheral nerves, adrenals, kidneys, liver and

spleen, result in the systemic pathology of the disease.

About one person in 10 who gets diphtheria dies of it. Diphtheria is more severe

for those under 5 and over 40 years of age.

Causal agent of Anthrax

Bacillus anthracis is a Gram positive rod that produces spores and is nonmotile.

There are three major anthrax syndromes: cutaneous (most common); inhalation

(most lethal); and gastrointestinal anthrax.

The essential virulence factors of anthrax are encoded on two plasmids: one codes

for an antiphagocytic capsule, and the other plasmid carries the toxin genes. Disease is caused by the actions of three exotoxin subunits:

•Edema factor (EF) edema.

•Lethal factor (LF) mitogen-activated protein (MAP) kinases leading to their inactivation

causing death through an unknown mechanism.

Anthrax Vaccine Adsorbed (AVA), containing a crude preparation of protective

antigen, is the only licensed human anthrax vaccine in the US.

biofilms

Gel-like polysaccharide trapping other

bacteria which protects the invading bacteria.

Difficult to clear. Film may be impermeable to antibiotics.

Pseudomonas aeruginosa

Alveoli biofilm with unactivated neutrophils

Cystic fibrosis

NO Archeae are

known to be

pathogenic

normal human microbiota

E. Coli in intestines digest food and make Vitamin K and B12

Most of the microbes living on

you do not cause disease, but

some are opportunistic.

Pathogenesis is a matter of

balance

skin

mouth

eyes

nose and throat

large intestine urinary and genital systems

Skin – the first line of defense

acidic secretions

little moisture*

radiation exposure

barrier preventing

entrance

*except armpits and between legs

Hand washing keeps

numbers down.

repopulated quickly from hair follicle and

sweat gland colonies

Propionibacteria acnes anaerobic

mouth and intestines

More than 300 species found in the mouth

Dental caries (cavity) one of the most

common infectious diseases in humans

today glucose - dextran

fructose – lactic acid

1,000,000/ml of saliva

• Enormous populations

• 40% of feces is bacteria

• Mostly anaerobic & facultative anaerobes

• Some synthesize vitamins

Archaebacteria differs from bacteria:

1. Cell Membrane

Form lipid monolayer instead of lipid bilayer (in methanogens and thermophilic archaebacteria)

2. Cell Wall

Archaebacteria has no muramic acid and D-amino acids.

Has pseudopeptidoglycan

3. Extremophiles

Most of them are thermophilic or methanogens.