1. Foundations in Microbiology Chapter 4 PowerPoint to accompany Fifth Edition Talaro Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Prokaryotic Profiles: the Bacteria and the Archaea Chapter 4

3. 3 Fig. 4.1 Stucture of a typical rod-shaped bacterial cell

4. 4 Appendages Provide motility Flagella- Axial filaments- Attachments or channels Sex pili- Fimbriae-

5. 5 flagella 3 parts –filament – long, thin, helical structure composed of a protein called flagellin –hook- curved sheath –basal body – stack of rings firmly anchored in cell wall rotates 360 o 1-2 or many distributed over entire cell functions in motility

6. Flagella

7. 7 Gram negative

8. 8 Flagellar arrangements 1.monotrichous – single flagellum at one end 2.lophotrichous – small bunches arising from one end of cell 3.amphitrichous – flagella at both ends of cell 4.peritrichous – flagella dispersed over surface of cell, slowest

9. 9 Monotrichous Lophotrichous Amphitrichous Peritrichous

10. 10 Fig 4.5 Counterclockwise = a run Clockwise = tumble

11. 11 Fig 4.6 Chemotaxis

12. 12 Axial Filaments Periplasmic, internal flagella, enclosed in the space between cell wall and cell membrane of spirochetes (corckscrew shaped bacteria) Function in motility

13. Periplasmic flagella on spirochete cell Electron micrograph of Borrelia burgdorferi, agent of lyme disease

14. 14 Fig 4.7a b Orientation of periplasmic flagella on the spirochete cell

15. 15 Fimbrae fine hairlike bristles from the cell surface function in adhesion to other cells and surfaces

16. 16 Fimbriae Pathogenic Escherichia coli covered with fimbriae E. coli tightly adhere to the surface of intestinal cells with their fimbriae

17. 17 Sex pili rigid tubular structure made of pilin protein found only in Gram negative cells Functions –joins bacterial cells for DNA transfer (conjugation) –adhesion

18. 18 Conjugation

19. 19 Glycocalyx Coating of molecules external to the cell wall, made of sugars and/or proteins 2 types 1.capsule - highly organized, tightly attached 2.slime layer - loosely organized and attached functions –attachment –inhibits killing by white blood cells –Protects from dehydration and loss of nutrients

20. 20 Fig 4.10

21. 21 2 Types of Glycocalyx

22. Fig. 4.12 Bacillus with and without capsules Special staining of Klebsiella highlighting the capsule

23. 23 Biofilms

24. Fig. 4.13 Biofilm Scanning electron micrograph of Staphylococcus aureus cells attached to catheter by a slime secretion

25. Cell wall composition

26. 26 Peptidoglycan unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments provides strong, flexible support to keep bacteria from bursting or collapsing because of changes in osmotic pressure Glycan = large polymers of simple sugars

27. 27 Structure of Peptidoglycan in the cell wall

28. Fig. 4.14c Structure of Peptidoglycan in the cell wall

29. 29 Peptidoglycan Lysozyme (enzyme in tears and salivia) hydrolyzes the bonds in glycan chains of invading bacteria, causing the wall to break down Several drugs including penicillin target the peptide cross-links in the peptidoglycan

30. 30 4 groups based on cell wall composition 1.Gram positive cells 2.Gram negative cells 3.Bacteria without cell walls-mycoplasms 4.Bacteria with chemically unique cell walls

31. 31 Gram positiveGram negative Fig 4.14 Fluid Mosiac Model

32. The Gram Stain: 1884- Hans Christian Gram

33. 33 Gram positive cell wall Consists of –a thick, homogenous sheath of peptidoglycan 20-80 nm thick –tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid (for cell wall maintenance and enlargement during cell division) –cell membrane Retain crystal violet and stain purple

34. 34

35. 35 Gram negative cell wall Consists of –an outer membrane containing lipopolysaccharide (LPS) –thin shell of peptidoglycan –periplasmic space –inner membrane Lose crystal violet and stain red from safranin counterstain

36. 36

37. Basic Internal Components

38. 38 Cytoplasm dense gelatinous solution of sugars, amino acids, & salts 70-80% water serves as solvent for materials used in all cell functions Prominent site for the cell’s biochemical and synthetic activities

39. 39 Chromosome single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell DNA is tightly coiled around a protein, aggregated in a dense area called the nucleoid Minimal genetic requirement for bacterial survival

40. Fig. 4.18 Fluorescent staining highlights the chromosomes of bacterial pathogen, Salmonella enteriditis

41. 41 plasmids small circular, double-stranded DNA free or integrated into the chromosome duplicated and passed on to offspring not essential to bacterial growth & metabolism may encode antibiotic resistance, tolerance to toxic metals, enzymes & toxins used in genetic engineering- readily manipulated & transferred from cell to cell

42. 42 ribosomes made of 60% ribosomal RNA & 40% protein consist of 2 subunits: large & small procaryotic differ from eucaryotic ribosomes in size & number of proteins site of protein synthesis All cells have ribosomes.

43. 43 Prokaryotic ribosome

44. 44 Inclusions and granules intracellular storage bodies vary in size, number & content bacterial cell can use them when environmental sources are depleted Examples: glycogen, poly-  -hydroxybutyrate, gas vesicles for floating, sulfur and polyphosphate granules

45. 45 Inclusions Large particles of polyhydrosybutyrate. Inclusion bodies provide long-term storage of that nutrient

46. 46 endospores Resting, dormant cells produced by some G+ genera: Clostridium, Bacillus & Sporosarcina Have a 2-phase life cycle – vegetative cell & an endospore sporulation -formation of endospores germination - return to vegetative growth hardiest of all life forms withstand extremes in heat, drying, freezing, radiation & chemicals not a means of reproduction

47. 47 endospores heat resistance linked to high levels of calcium & dipicolinic acid dehydrated, metabolically inactive thick coat longevity verges on immortality 25 to 250 million years. pressurized steam at 120 o C for 20-30 minutes will destroy (the autoclave)

48. 48 Medical significant endospores Bacillus anthracis- anthrax agent, candidate of bioterrorism Clostridium genus- –C. tetani - the cause of tetanus (lockjaw) –C. perfringens - cause of gas gangrene (spores germinate in dead tissue, germinate, grow, and release potent toxins –C. botulinum - agent of botulism, deadly form of food-poisoning

49. 49 endospores

50. Fig. 4.21

51. 51 Bacterial shapes and arrangements cocci - spherical bacilli - rod spiral - helical, comma, twisted rod, spirochete (flexible spring) and spirillum (rigid corkscrew)

52. Fig. 4.25

53. 53

54. 54 Methods in bacterial identification 1.Microscopic morphology 2.Macroscopic morphology – colony appearance 3.Physiological / biochemical characteristics 4.Chemical analysis 5.Serological analysis- immune response 6.Genetic & molecular analysis G + C base composition DNA analysis using genetic probes Nucleic acid sequencing & rRNA analysis

55. 55 species –a collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars) –Serratia marcescens - pigments and nonpigmented strains –Pseudomonas fluorescens - flagellated and nonflagellated strains type – a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype).

56. Prokaryotes with unusual characteristics

57. 57 Rickettsias very tiny, gram-negative bacteria most are pathogens that alternate between mammals and fleas, lice or ticks (blood-sucking arthropods) obligate intracellular pathogens cannot survive or multiply outside of a host cell cannot carry out metabolism on their own Rickettsia rickettisii – Rocky Mountain spotted fever, ticks Rickettsia prowazekii – endemic typhus, lice

58. TEM of the rickettsia Coxiella burntii, cause of Q fever

59. 59 Chlamydias tiny obligate intracellular parasites (require host cells for growth and metabolism) not transmitted by arthropods Chlamydia trachomatis – severe eye infection and one of the most common sexually transmitted diseases Chlamydia pneumoniae – lung infections

60. 60 Mycoplasmas Bacteria that naturally lack a cell wall stabilized by sterols, resistant to lysis extremely small range in shape from filamentous to coccus or doughnut shaped –Pleomorphism - extreme variation of shape Mycoplasma pneumoniae – atypical pneumonia in humans, adheres to epithelial cells in the lung

61. Fig. 4.32 Scanning electron micrograph of Mycoplasma pnuemoniae (62,000x)

62. 62 Free-living nonpathogenic bacteria Photosynthetic bacteria –Cyanobacteria (oldest) –Green & purple sulfur bacteria Gliding, fruiting bacteria

63. Fig. 4.34 Concentrated bloom of purple sulfur bacteria

64. Fig. 4.35 Lifecycle of Chondromyces a fruiting bacteria

65. 65 Archaea: the other prokaryotes constitute third Domain Archaea Unusual biochemistry and genetics that make them different than bacteria seem more closely related to Domain Eukarya than to bacteria contain unique genetic sequences in their rRNA have unique membrane lipids & cell wall construction live in the most extreme habitats in nature, extremophiles adapted to heat, salt, acid, pH, pressure & atmosphere includes: methane producers, hyperthermophiles, extreme halophiles, and sulfur reducers

66. Red Archea bacteria dominate the solar evaporation pond in Owens lake, CA (high salt content)

67. Fig. 4.30