Bacteria

1. Bacteria

2. Bacteria • All bacteria share several common characteristics • Unicellular (although some stick together in colonies) • Prokaryotic – no nucleus, lack most cell organelles • Single chromosome • Reproduce through binary fission • Need moist environment • Have rigid outer wall that give it shape

3. Archaebacteria occupy environmental extremes Thermoacidophiles Halophiles Methanogens probable ancestor of Eukaroyotes Eubacteria modern species have different RNA and gene products includes most of the bacteria encountered in daily life Two Kingdoms or Two Domains

4. Archaebacteria • Desended from one of the oldest groups of living organisms on earth • Live in areas of such extreme conditions that nothing else survives there

5. 3 major groups Thermophiles Methanogens • Live in areas of more than 45 C • Some obtain energy from metabolizing sulfur compounds • Live near sulfur hot springs • Enzyme Taq polymerase (from Thermusaquaticus) is used in molecular genetics (DNA replication) • Grow in areas without oxygen • Use CO2 and H2O to produce methane • Live in volcanic deep-sea vent and mammalian intestines • Used to help digest sewage and oil spills

6. Halophiles • Live in areas that are very saline such as salt flats and evaporation ponds • Have a bright red pigment that allow to capture sunlight for energy • Used for cancer reasearch

7. Eubacteria • The most common member of this Kingdom is Escherichia coli • Live in human intestines helping with food digestion and some vitamin synthesis • In too high levels it can be dangerous

9. Each new E. coli is about 1m in length (0.00000 1m) • A line of 250 could be seen by the naked eye • A distinction of this kingdom is the structure of the cell wall, however not all have a cell wall • They have a polymer called peptioglycan

10. The two types of Eubacteria (with or without a cell wall) can be distinguished by a Gram Strain • Cells are stained with crystal violet (purple dye) • Dye is fixed, cell is “washed” with a decolourizer • Stained again with safranin (red dye) • Those with peptioglycan retain the purple colour (Gram Positive) while those without lose the purple and so take on second stain pink (Gram Negative) • (Staph - +ve , E. Coli –ve)

12. Streptococcus

13. Gram Negative

15. Characterized by 3 shapes • Cocci spherical --- • bacilli  rod-shaped --------------- • Spirilla spiral

16. Bacterial Shape

17. Configuration • After they divide some cells stay together in groups • If they form a chain they are given the prefix strepto • Ie. Streptococcus mutans(tooth decay)

18. If they form a cluster they are given the name staphylo • Ie. Staphylococcus aureus (found on skin)

19. Streptobacillus

20. Bacterial Shape staphylococcus streptococcus diplococcus

21. diplobacillus staphylobacillus streptobacillus

23. Streptococcus

25. Streptobacillus

26. Spirochetes

27. Helical rods

28. Tetrads

29. Typical Bacterial Characteristics • Flagella- whip-like locomotor structure • Pili-hollow tube for attachment or exhange of DNA during conjugation • Cell membrane lies inside wall carries on metabolism and synthesis • Plasmid ring of DNA that may be exchanged between bacteria and may direct antibiotic production

30. 4

31. Capsule- for attachment and protection, • sticky with various polysaccharides , may • cause disease. • Pilis- hollow tubes for attachment or exchange • of DNA (conjugation) • Motility- by flagella with some ability to move • towards food • Genome- DNA one large circular chromosome • and smaller rings of DNA called PLASMIDS • Endospores- resistant stage for survival of • harsh conditions

32. Capsule- for attachment and protection,sticky with various polysaccharides , may cause disease. Pilis- hollow tubes for attachment or exchange of DNA (conjugation)

33. Nutrition • Autotrophs– make their own food from inorganic substances • Photosynthetic – convert CO2, H2O and light energy into carbohydrates • Chemosynthetic – use chemical reactions to provide them with energy • Heterotrophs – obtain their energy by consuming other organisms (i.e. Dead, decaying organisms, or by living as parasites on living tissues)

34. Respiration • Anaerobic • does not require it • Aerobic • Requires O2

35. Reproduction • Asexually through binary fission • i.e. Pyrodictiumabyssi • Sexually through Conjugation • i.e. Salmonella

36. Short life cycle 20 min-3 hrs. doubling time

37. Binnary Fission

38. Binary Fission

39. Conjugation • Genes are exchanged via a sex pilus

41. Spore Formation Endospores- resistant stage for survival of harsh dry or hot environments

43. Bacterial Pathogens CAUSE DISEASE • Endostoxins- protein or other chemical toxins found within the microbe released when cell dies. • Exotoxins- released by pathogen

44. How we Control Bacteria • Temperature- exceed range of tolerance autoclave- heat under pressure pasteurization-heat to below 100 degrees C. refrigiration- slows only, not good for psychrophilic • UV light- destroys DNA • Chemical antisepic- on living tissue disinfectant-on inanimate objects antibiotic-produced by living things

45. Koch's postulates (or Henle-Koch postulates) • Are four criteria designed to establish a causal relationship between a causative microbe and a disease. • The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884 and refined and published by Koch in 1890. • Koch applied the postulates to establish the etiology of anthrax and tuberculosis, but they have been generalized to other diseases.

46. KOCH’S POSTULATE • Isolate the suspected pathogen and grow in pure culture • Inoculate a healthy host • Look for symptoms • Re-isolate and compare to original pathogen