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BACTERIA PowerPoint Presentation


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  1. ARCHAEBACTERIA Introns in DNA Lack peptidogycan in cell walls Live in extreme environments EUBACTERIA Includes most bacteria Most have one of three shapes May be divided into up to 12 phyla Classification is controversial BACTERIA

  2. TYPES OF ARCHAEBACTERIA Methanogens living in sewage Thermoacidophilies Living in hot springs Extreme halophile living in the Great Salt Lake


  4. Gram-Negative Lack thicker layer of peptidoglycan Stain pink Endotoxins Gram-Positive Thicker layer of peptidogycan Stain purple Exotoxins (released when bacteria die) Gram- negative Most Species of Eubacteria may be Grouped Based on Staining Gram-positive

  5. Nutrition and Growth • Saprophtes ex: decomposers • Photoautotrophs ex: blue-green algae • Obligate anaerobes ex: tetanus • Facultative anaerobes ex: E.Coli • Obligate aerobes ex: tuberculosis • Thermophilic bacteria Most bacteria grow at at neutral pH but some grow best at a pH of 6 or lower • Bacteria that produce yogurt and sour cream

  6. E. coli • E. coli is the lab rat of the bacterial world. • E. coli is a normal resident of the large intestine in healthy people. It is a type of probiotic organism because it crowds out disease causing bacteria. E. coli also makes vitamin K which humans require to be healthy. • Although it is generally a good microbe, some strains make people sick. The toxic strains of this microbe are responsible for about half of all cases of traveler's diarrhea. One famous strain, O157:H7, has caused disease in people who eat uncooked hamburger.

  7. Thermophiles • These bacteria feed an animal that cannot eat. The relatives of this microbe make life possible deep beneath the ocean near volcanic vents. This particular microbe lives inside and feeds tall white worms sporting red, feathery caps, that live at the dark bottom of the sea. • The microbes and the worm depend upon each other for survival in what is called a symbioticrelationship.

  8. Sewage Sludge • Sewage is home to many microbes. Many of these microbes are the main workers in cleaning up sewage sludge. They eat the sludge and release carbon dioxide gas,water and trace minerals. These weird, coiled-shaped microbes live with other microbes in a culture from sewage sludge. • The bacterium shown above is unusual because it is coiled. No on knows why they grow in coils.

  9. Serratia marscescens • This common microbe is found in soil, water, on plants and in animals. • Most microbiologists are all too familiar with Serratia marscescens, one of the most frequent contaminants of Petri plates in the lab. This same organism also grows on bread and communion wafers which have been stored in a damp place.

  10. Bacillus cereus • Bacillus cereus is a Gram positive, aerobic, spore-forming, rod-shaped bacterium. Like many bacteria, B. cereus is both a friend and a foe of humans. Sometimes it behaves as a friend in that it is used as a form of biocontrol to help us get rid of unwanted pests. For example, B. cereus deters certain fungi from rotting seedling plants. • B. cereus can also be a serious foe when it causes food poisoning.


  12. Genetic Recombination Transformation - Bacteria take in DNA from its external environment. Transduction – a virus obtains DNA from host bacteris Conjugation

  13. Conjugation of E. coli

  14. Antibiotics • Antibiotics are drugs that combat bacteria by interfering with cellular functions • Penicillin – interferes with cell wall production • Tetracycline – interferes with protein production • Sulfa drugs – produced in the laboratory • Broad-spectrum antibiotics will affect a wide variety of organisms

  15. Penicillin • This amazing fungus produces the famous antibiotic, penicillin. In 1928. Alexander Fleming observed that a mold called Penicillium notatum produced a substance, later known as penicillin, that killed bacteria in its presence. This antibiotic was the first of many to be found and used to treat infections. • Interferes with cell wall production. This fungus makes antibiotics and cheese. Other varieties of the fungus produce blue cheese and Roquefort cheeses.