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Microbiology Unit 2-3: Bacteria
- 1. Microbiology and Parasitology UNIT2/3: BACTERIA
- 2. Microbiology Virus: Ebola Algae: Algalbloom Fungi: Mushroom Bacteria: Salmonella ENEMY OR… …FRIEND
- 3. Test your memory A.True or False 1. Microbiology is the study of disease-causing microorganisms 2. Microbes are involved in the production of food and drinks 3. Fungi are a type of acellular microorganisms 4. The majority of our microflora are “microbial allies” 5. Microbial intoxication is a type of infectious disease B. Multiple choice 1. Who invented the microscope a) Pasteur; b) van Leeuwenhoek; c) Fleming 2. Koch’s Postulates proves that a) Microbes can be isolated from an infected animal; b) Microbes are always found in the same animal species; c) Specific microbes cause particular diseases 3. Ignaz Semmelweis is reffered to as a) Father of Microbiology; b) Father of Handwashing; c) Father of Hygiene
- 4. Variety of Microbes •Categories – Acellar: Viroids, Virus, Prion – Prokaryotes (cellular without nucleus): Bacteria, Archaea, Cyanobacteria – Eukaryotes (cellular with nucleus): Algae, Fungi, Protozoa Microbes Acellular Viroids Prions Virusus Cellular Prokaryotes Archaea Bacteria Cyanobacteria Eukaryotes Algae Fungi Protozoa
- 5. Today • Classification – Taxonomy –Morphology • Structure of cells • (Endo)spores • Cell reproduction – Binary fission – Generation time • Bacterial growth – Encouraging growth – Inhibiting growth • Staining • Other characteristics • Unique bacteria – Rickettsia
- 6. Microbial classification • Millionsof species on Earth – Bring order in the chaos: system to classify organisms – Taxonomy = science of classification of species – Classification, nomenclature and identification (complicated system) – Scientist still debate about the system Burton’s Microbiology: Chapter 3,4 23 32 77 182 871 5007 Only 1% known? 3 or 5?
- 7. Classification by shape •Categories based on shape of their cells (simpler system) – Spherical: cocci – Rod-shaped: bacilli – Short rods/elongated spheres: coccobacilli – Curved/Spiral-shaped: spiralla (spirochetes) – Various shapes: Pleomorphic (cell wall-deficient bacteria) BacilliCocci Curved/spiral Burton’s Microbiology: Chapter 4
- 8. Morphology of cocci Burton’sMicrobiology: Chapter 4 Chains Clusters • Bacteria aggregate: morphological arrangement
- 9. Morphology of bacilli Chains:streptobacilli Side-by-side: DiphtheroidsPairs: Diplobacilli Short rods: Coccobacilli Burton’s Microbiology: Chapter 4
- 10. Morphology of spirochetes Lesstightly coiledTightly coiled highly flexible cell wall able to move through tissue Treponema pallidum: Syphilis Borrelia: Lyme disease Burton’s Microbiology: Chapter 4
- 11. Size of bacteria •Spherical bacteria: Coccus – Typical diameter: 1 μm (1 million micrometers = 1 meter) – Seven cocci fit the diameter of human red blood cell • Rod-shaped bacteria: Bacillus – Typical length: 3 μm – Typical width: 1 μm Burton’s Microbiology: Chapter 2
- 12. Structure: Advanced microscopes (Optical)Light Microscope x1000 Scanning Electron Microscope (SEM) x10.000 Transmission Electron Microscope (TEM) x100.000 1 μm “STAPHYLOCOCCCUS AUREUS” Burton’s Microbiology: Chapter 2,3 “Study the structure of cells in detail”
- 13. Cell structure Burton’s Microbiology:Chapter 3 • Cell – Fundamental unit of a living organism – Basic characteristics of life • Cell = tiny functional factory – Metabolism: all chemical reactions in a cell – Use food (nutrients) to produce energy – Grow and reproduce – Responds to environment – Can mutate (change genetically) • Study of cell structure – Cytology
- 14. Procaryotic cell • Bacteria:Procaryotic cell – Cell envelope • Cell membrane • Cell wall • Slime layers and Capsules – Chromosome – Cytoplasm • Cytoplasmic Particles – Flagella and Pili – (Endo)spores Burton’s Microbiology: Chapter 3 Difference with eucaryotes: 10x smaller than eucaryotic cell Less complex cell structure: no nucleus
- 15. Cell envelope • Cellmembrane – Flexible thin skin that encloses the cells interior – Controls in/out transport of substances (via proteins in membrane) • Cell wall – Provide rigidity, strength and protection – Different structure for Gram+ and Gram- bacteria – Cell wall-deficient (CWD) bacteria: cause chronic diseases, e.g. Lyme • Glycocalyx (external layer) – Slime layer: slide along solid surfaces – Capsule: protection (white blood cells) Burton’s Microbiology: Chapter 3,4
- 16. Bacterial genome Burton’s Microbiology:Chapter 3 • Genome carries genetic information (3000 genes) – Chromosome • Duplicating itself • Guiding cell division • Directing cellular activity • Embedded in cytoplasm – Plasmid
- 17. Nutrient matrix • Cytoplasm –Semifluid nutrient matrix of cell • Cytoplasmic particles – Complex mixture of all materials required for metabolic functions of cell – Mostly ribosomes, sites for protein synthesis Burton’s Microbiology: Chapter 3
- 18. Flagella and Pili •Flagella – Threads of protein – Movement: flagellated bacteria are motile – Number and arrangment vary Burton’s Microbiology: Chapter 3 • Pili (fimbriae) – Hair-like structures (gram-) – Rigid, not associated with movement – Adhere/attach to surfaces (e.g. human body tissues) – Sex pilus: transfer of genetic material (plasmid) from one bacteria to another Salmonella cell
- 19. Spores Burton’s Microbiology: Chapter3 • Endospores (some bacteria) – Thick protein coat – In order to survive when moisture or nutrient supply is low – Resistant to heat/cold/drying/chemicals • Sporulation – Process to form endospores – Copy of chromosome (most valuable) and cytoplasm enclosed • Germination – Dried spore lands on moist nutrient-rich surface – New bacterial cell emerges (a seed) Terminal spores Subterminal spores
- 20. Cell reproduction • Binaryfission (reproduction) – Chromosome is duplicated (DNA replication) – Parent cell splits in half to become two daughter cells – Daughter cells contain same genetic info as parent cell Burton’s Microbiology: Chapter 3 Binary fission
- 21. Generation • Generation time –Time it takes to splitt cells – Depends on species and conditions (pH, T, nutrients) • Slow and rapid growers – E. coli: 20 minutes (ideal conditions) • Mathematics – What time does E. coli need to reach a population of 1.000.000, starting from just two bacterial cells? Burton’s Microbiology: Chapter 3
- 22. Bacterial growth Burton’s Microbiology:Chapter 8 Encouraging/Inhibting growth MICROBIOLOGY LABORATORY In vitro: outside the body Artificial culture media Growth requirements Inoculate & Incubate Population growth curve
- 23. Factors affecting growth •Fundamental needs of microbes – Nutrients: energy sources (C, H, O, S, P, N) – Moisture: Water – Temperature: thermophiles or pshychrophiles – pH: acidity or alkalinity – Pressure: Osmotic (cell membrane) and barometric pressure (atmosphere) – Atmosphere: O2 and CO2 Burton’s Microbiology: Chapter 8
- 24. Encouraging growth • Bacterialgrowth – No increase in size, but increase in number (multiplication) – Binary fission results in bacterial colony – Control the (ideal) conditions for optimum growth • Culture media in the lab, artificial – Content: chemically defined / complex – State: solid / liquid – Growth: selective / differential • Culturing bacteria in the lab, in vitro – Clinical lab: Enable identification of pathogens – Research lab: Study, harvest antibiotics, produce vaccines – Industry lab: Produce microbes for food/beverage companies Burton’s Microbiology: Chapter 8 Selective: only Gram- Differential: lactose- fermenters turn pink
- 25. Culture bacteria 1. Inoculate –Add bacteria (specimen) to medium – Sterile: prevent contamination 2. Incubate – Chamber with appropriate conditions – Monitor temperature and atmosphere Burton’s Microbiology: Chapter 8 3. Count population – Determine bacterial growth – Bacterial population growth curve • Lag: absorb nutrients • Log: binary fission (growth) • Stationary: lack of nutrients • Death: toxic waste Innoculation of solid agar
- 26. Growth EXPERIMENT 001 Title: Potatogerms Topic: Growth of bacteria 1. Peel and slice potato (with gloves) in 4 pieces of equal size 2. Put one slice (with gloves) in box labeled “control” 3. Put second slice (with gloves) in box labeled “oral” and cough/blow on it 4. Take third slice and rub it on the table before putting it in box labeled “table” 5. Take out your gloves and rub fourth slice with your hands before putting it in box labeled “hands”
- 27. Inhibiting growth • Physicalmethods – Heat / Cold – Heat + pressure – Desiccation (freeze-drying) – Radiation / Ultrasonic waves – Filtration – Gaseous atmosphere • Chemical methods – Disinfection (soap/alcohol) • Chemical agents on materials (nonliving) – Antisepsis (prevent infection) • Chemical agents on body (living) “Inhibiting: from reducing microbial growth to killing pathogens” Burton’s Microbiology: Chapter 8
- 28. Classification by staining •Observing microbes – Bacteria are colorless, transparent: difficult to see • Examine bacteria via staining – Smear – Dry – Fix • Kills organisms • Preserves morphology • Anchors to slide – Observe cell morphology • Size • Shape • Arrangement • Cell walls, capsules, flagella, endospores Burton’s Microbiology: Chapter 4
- 29. Simple stain Dye: methyleneblue Burton’s Microbiology: Chapter 4 • Determine shape and morphological arrangement
- 30. Gram staining (1) •Gram staining procedure – By Dr. H.C. Gram (1883) – Most important staining method • Differentiates Gram- / Gram+ • Color depends on cell wall structure – Gram+ = blue-to-purple – Gram- = pink-to-red Burton’s Microbiology: Chapter 4
- 31. Gram staining (2) Gramnegative Gram positive Burton’s Microbiology: Chapter 4 Result of Gram staining
- 32. Overview of staining •Acid-fast staining – To stain gram-variable bacteria (Mycobacterium) • M. tuberculosis in sputum of TB patient • M. leprae Burton’s Microbiology: Chapter 4 Acid-fast TB bacilli
- 33. Characteristics of bacteria •Characteristics used to identify bacteria • Already discussed… – Cell shape (cocci, bacilli, spiral-shaped, etc.) – Morphological arrangement (chains, clusters, pairs, coiled, etc.) – Staining reactions (gram+, gram-, no cell wall) • But there is more… – Motility – Colony morphology – Atmospheric requirements – Nutrional requirements – Biochemical and metabolic activities – Pathogenicity – Genetic composition Burton’s Microbiology: Chapter 4
- 34. Motility • Motility ofbacteria – Bacterium is able to “swim” – Associated with presence of flagella – Determined with semisolid agar method • Pattern of growth of nonmotile organism – Turbidity only seen along stab line – Most cocci are unmotile • Pattern of growth of motile organism – Turbidity throughout the medium – Most spiral-shaped and half of bacilli Burton’s Microbiology: Chapter 4 Semisolid agar method
- 35. Colony morphology • Whenbacteria divides over and over… – … the result is a colony – Colony contains millions of microbes – Morphology varies in: • Size (indication for growth rate) • Color • Shape • Elevation • Appearance at edge Burton’s Microbiology: Chapter 4
- 36. Atmosphere • Classify bacteriaon relationship to O2 or CO2 Burton’s Microbiology: Chapter 4 Require ~20% O2 Prefer ~5% O2 Require 0% O2 Prefer 0% O2 No preference Majority of clinical specimens
- 37. Nutrition and Activities •Biochemical and metabolic activities – Characterize by waste products • Secretion of enzymes or gases • Nutritional requirements – All: C, H, O, S, P, N – Some: K, Ca, Fe, Mn, Mg, Co, Cu, Zn, U, vitamins – Demanding: Fastidious (fussy) Burton’s Microbiology: Chapter 4
- 38. Pathogenicity Burton’s Microbiology: Chapter4 • Ability to cause disease – Many pathogens are able to cause disease due to… • Capsules • Pili • Endotoxins • Exotoxins • Enzymes – …which damage cells and tissues
- 39. Genetic composition • Moleculardiagnostic procedures – Modern labs: analyze DNA or RNA of bacteria – Identify organism by composition of genetic material – Determine relatedness between two species Burton’s Microbiology: Chapter 4
- 40. Unique bacteria • Rudimentary(unique) bacteria: different from the others… – Rickettsias & Chlamydias • Pathogen must live within host cell (like a virus) – Mycoplasmas: lack cell walls • Occur in many shapes: pleomorphic • No Gram staining possible • Resistant to treatment with penicillin • Can be free-living or parasitic pathogens – Megabacteria (750 μm) & Nanobacteria (20 nm) • Photosynthetic bacteria – Use light as energy source – e.g. Cyanobacteria • Produce oxygen, oxygenation of the atmosphere • Like blue green algae that overgrow lakes (toxic) Burton’s Microbiology: Chapter 4
- 41. Rickettsias (1) • Uniquebacteria: Rickettsias – Named after Howard T. Ricketts – Gram- cell wall – Obligate intracellular pathogen • Must live within host cell • Cannot grow on artificial (synthetic) culture media • Grow inside eggs/animals/cell cultures – Disease (transmitted by lice, fleas, ticks) • Rickettsialpox • Epidemic and Endemic typhus • Rocky Mountain spotted fever – Medicine: Tetracyclines • Attack bacterial ribosomes (site for protein synthesis) Burton’s Microbiology: Chapter 4,8,9
- 42. Rickettsias (2) • Obligateintracellular pathogen – Invade and live in host cells – Produce their own proteins and RNA/DNA – Still require intracellular environment: “leaky membranes” • Intracellular survival mechanisms – Attack: Phagocytes (like white blood cells) protect body, destroy pathogens – Protection: Rickettsias produces enzymes that destroy the interior of the phagocytes Burton’s Microbiology: Chapter 4,14
- 43.