1. Plants, like most animals, are multicellular eukaryotes Eubacteria Archaea Animals Plants Fungi Common ancestors Photo credits: Public Health Image Library; NASA; © Dave Powell, USDA Forest Service; tom donald Protists

2. 2 PROKARYOTES BACTERIAARCHAEA EUKARYOTES EUKARYOTES

3. 3 Prokaryotes (Bacteria) Eubacter "True" bacteriaEubacter "True" bacteria – human and plant pathogens – clinical or environmental – one kingdom Archaea Archaea – Environmental organisms – second kingdom

4. 4 Prokaryotic Cell (versus Eukaryotic Cell) Not compartmentalizedNot compartmentalized Cell membranes lack sterols (e.g. cholesterol)Cell membranes lack sterols (e.g. cholesterol) Single circular chromosomeSingle circular chromosome Ribosomal are 70SRibosomal are 70S - subunits 30S (16S rRNA)30S (16S rRNA) 50S (5S & 23S rRNA)50S (5S & 23S rRNA)

5. 5 Bacteria versus Archaebacteria EubacteriaEubacteria –peptidoglycan (murein) –muramic acid ArchaebacteriaArchaebacteria –pseudomurein –no muramic acid 16S rRNA16S rRNA –sequence different

6. 6 Morphology ShapeShape –cocci (round) –bacilli (rods) –spiral or curved (e.g. spirochetes) Single or multiple cellsSingle or multiple cells –clusters (e.g. staphylococci) –chains (e.g. streptococci)

7. 7 Bacterial requirements for growth oxygen (or absence)oxygen (or absence) energyenergy nutrientsnutrients optimal temperatureoptimal temperature optimal pHoptimal pH

8. 8 Obligate aerobes grow in presence of oxygen grow in presence of oxygen no fermentation no fermentation oxidative phosphorylation oxidative phosphorylation

9. 9 no oxidative phosphorylation fermentation killed by oxygen lack certain enzymes: superoxide dismutase O 2 - +2H + H 2 O 2 catalase H 2 O 2 H 2 0 + O 2 peroxidase H 2 O 2 + NADH + H + 2H 2 0 + NAD Obligate anaerobes

10. 10 Aerotolerant anaerobes respire anaerobicallyrespire anaerobically not killed by oxygennot killed by oxygen

11. 11 Facultative anaerobes fermentationfermentation aerobic respirationaerobic respiration survive in oxygensurvive in oxygen

12. 12 Microaerophilic bacteria growgrow –low oxygen killedkilled –high oxygen

13. 13 Nutrient Requirements CarbonCarbon NitrogenNitrogen PhosphorusPhosphorus SulfurSulfur Metal ions (e.g. iron)Metal ions (e.g. iron)

14. 14 Measuring bacterial mass (live + dead) in liquid culture Turbidity(Cloudiness)

15. 15 Measuring viable bacteria colony Colony forming units

16. 16 Growth Curve COLONY FORMING UNITS TIME Lag Log Stationary Death

17. 17 Growth Curve TURBIDITY (cloudiness) TIME Lag Log Stationary Autolysis

18. 18 Generation time time for bacterial mass to doubletime for bacterial mass to double ExampleExample 100 bacteria present at time 0 100 bacteria present at time 0 If generation time is 2 hr If generation time is 2 hr After 8 hr mass = 100 x 2 4 After 8 hr mass = 100 x 2 4

19. 19 Eukaryotic cellProkaryotic cell Gram + Gram - Cell wall Rough endoplasmic reticulum Mitochondria (e.g. animal) Nucleoid/ nucleoid region Nucleus Cell membrane Cytoplasm Flagellum Cell (inner) membraneOuter membrane Ribosomes Granule Cell wall Capsule Pili

20. 20 Extra-chromosomal DNA multiple copy number coding - pathogenesis factors - antibiotic resistance factors bacterial replication Plasmids

21. 21 ell membrane + cell wall (+ plus outer membrane) Cell membrane + cell wall (+ plus outer membrane) Cell wall Cell wall – peptidoglycan – attached structures The Cell Envelope

22. 22 Cytoplasm Oxidative phosphorylation occurs at cell membrane (since there are no mitochondria). Cell membrane The cell wall is outside of cell membrane – rigid, protecting cell from osmotic lysis & some antibiotics. Cell Wall

23. 23 Gram Positive Gram Negative

24. 24 GRAM POSITIVE GRAM NEGATIVE Cytoplasm Cytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Inner (cytoplasmic) membrane Outer Membrane Lipopolysaccharide Porin Braun lipoprotein Periplasmic space

25. 25 Peptidoglycan single macromolecule single macromolecule highly cross-linked highly cross-linked surrounds cell surrounds cell provides rigidity provides rigidity

26. 26 Peptidoglycan glycan backbone –muramic acid –glucosamine peptide side chain peptide cross-bridge –D- and L- amino acids –diaminopimelic acid

27. 27 Muramic acid, D-amino acids diaminopimelic acid – not synthesized by mammals

28. 28 Peptidoglycan Muramic acid Glucosamine L-alanine D-glutamic acid L-lysine/Diaminopimelic acid D-alanine

29. 29 Cytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane GRAM POSITIVE CELL ENVELOPE Degradative enzyme

30. 30 Gram Positive Cell Envelope Teichoic acid –polymer –ribitol phosphate or ribitol glycerol backbone – Teichuronic acid –polymer –no phosphorus –glucuronic acid

31. 31 Teichoic and teichuronic acids Metal ion uptake Direct autolytic enzymes –holes punched in cell wall –allows insertion cell wall (synthesis)

32. 32 Lipoteichoic acids cell membrane autolysins kept from cell wall

33. 33 GRAM NEGATIVE CELL ENVELOPE Cytoplasm Inner (cytoplasmic) membrane Outer Membrane (Major permeability barrier) Lipopolysaccharide Porin Braun lipoprotein Periplasmic space Degradative enzyme Periplasmic binding protein Permease

34. 34 Braun lipoproteinBraun lipoprotein –binds cell wall to outer membrane Gram Negative Peptidoglycan

35. 35 Outer Membrane lipopolysaccharidelipopolysaccharide phospholipidsphospholipids ProteinsProteins –porins

36. 36 Outer Membrane Gram negative bacteria Gram negative bacteria major permeability barriermajor permeability barrier space between inner and outer membranespace between inner and outer membrane –periplasmic space  store degradative enzymes Gram positive bacteria no periplasmic spaceno periplasmic space

37. 37 Lipopolysaccharide synthesis similar to peptidoglycan also on undecaprenol carrier

38. 38 Lipopolysaccharide Lipid A Glucosamine disaccharide Beta hydroxy fatty acids Core Heptoses Ketodeoxyoctonic acid O-antigen Highly variable n

39. 39 FLAGELLA Some bacteria are motileSome bacteria are motile Locomotory organelles- flagellaLocomotory organelles- flagella Taste environmentTaste environment Respond to food/poisonRespond to food/poison –chemotaxis

40. 40 Flagella –embedded in cell membrane –project as strand –Flagellin (protein) subunits –move cell by propeller like action A: monotrichous B: Lophotrichous C: Amphitrichous D: Petritrichous

41. 41 Pili (fimbriae) hair-like projections of the cell hair-like projections of the cell sexual conjugation sexual conjugation adhesion to host epithelium adhesion to host epithelium

42. 42 Capsules and slime layers outside cell envelopeoutside cell envelope well defined: capsulewell defined: capsule not defined: slime layer or glycocalyxnot defined: slime layer or glycocalyx usually polysaccharideusually polysaccharide often lost during in vitro cultureoften lost during in vitro culture protective in vivoprotective in vivo

43. 43 Endospores (spores) Dormant cellDormant cell Produced when starvedProduced when starved Resistant to adverse conditionsResistant to adverse conditions - high temperatures - organic solvents contain calcium dipicolinatecontain calcium dipicolinate Bacillus and ClostridiumBacillus and Clostridium

44. 44 Koch's postulates isolatedisolated –diseased not healthy organisms growthgrowth –pure culture induce diseaseinduce disease –susceptible organisms re-isolatedre-isolated –susceptible organisms