A BRIEF DISCUSSION OF BACTERIA

Bacteria

singular: bacterium / plural: bacteria

1. Bacteria are classified into two kingdoms:

Eubacteria (true bacteria)
Archaebacteria (Ancient Bacteria).

2. BACTERIA are microscopic prokaryotes.  (“before nucleus”)
3. Adapted to living in all environments (even some extreme) – they exist everywhere

I.  Bacterial Structure

II.  Reproduction in Prokaryotes

Binary fission is the splitting of a parent cell into two daughter cells; it is asexual reproduction in prokaryotes.

In bacteria, genetic recombination can occur in three ways.

1. Conjugation
2. Transformation
3. Transduction

III.  Prokaryotic Nutrition

1.   Bacteria differ in their need for, and tolerance of, oxygen (O2).

a.   Obligate anaerobes
b.   Facultative anaerobes
c.   Aerobic organisms

2.   Autotrophic Prokaryotes

a.   Photoautotrophs
b.   Chemoautotrophs

3.   Heterotrophic Prokaryotes

a. Most free‑living bacteria are chemoheterotrophs that take in pre-formed organic nutrients.
b. Some chemoheterotrophs are symbiotic, forming relationships with members of other species

Mutualistic nitrogen‑fixing Rhizobium bacteria live on roots of soybean, clover, and alfalfa where they reduce N2 to ammonia
Mutualistic bacteria that live in the intestines of humans benefit from undigested material and help us break down food

IV.  BACTERIA CLASSIFICATION

1.   The Gram stain procedure (developed in the late 1880s by Hans Christian Gram)

a.   Gram‑positive bacteria stain purple, whereas Gram‑negative bacteria stain pink.
b.   This difference is dependent on the thick or thin (respectively) peptidoglycan cell wall.

2.   Bacteria have three basic shapes.

spirillum
bacillus
Coccus

3. Those shapes can be organized into

staph = clusters
strep = chains

A. Bacillus B. Streptococcus C. Staphylococcus D. Diplococcus E. Spirllum F. Vibrio

V. How Gram Stains are Made

VI. Bacteria and Health

Streptococcus	strep throat, related bacteria causes necrotizing fasciitis
Staphylococcus aureas	found on skin, responsible for minor infections, boils, pimples MRSA is an antibiotic resistant form
Bacillus subtilis	common lab bacteria, easy to grown, unharmful
Bacillus tetani	causes tetanus (lockjaw), most people are vaccinated
Clostridium botulism	causes botulism (food poisoning)
Yersinia (bacillus) pestis	causes Black Plague
Bacillus anthracis	anthrax
Mycoplasmas	very very tiny, cause of pneumonia
Rickettsia rickettsi	link between bacteria and viruses, can't reproduce outside host, causes Rocky Mountain Spotted Fever
Escherichia coli	E. coli - common bacteria of the digestive tract, also causes food poisoning
Salmonella	Belongs to same family as E. coli, also causes food poisoning

Antibiotics and Antiseptics

Joseph Lister created the first antiseptic, an acid to spray on tables and instruments before surgery (1860)
The Discovery of Penicillin

1. Alexander Fleming noticed mold growing on petri dishes
2. Bacteria did not grow where the mold was growing
3. He isolated the chemical from the bold that was killing the bactera
4. Howard Flory built upon his work and stabilized the chemical
5. Both Fleming and Flory received a Nobel Prize in 1945


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WRITTEN BY
KABIR HUSSAIN BAIG