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Bacterial Culture Methods ppt

  1. 1. BACTERIAL CULTURE METHODS BASICS Dr.T.V.Rao MD DR.T.V.RAO MD 1
  2. 2. BACTERIAL NUTRITION AND THE DESIGN OF CULTURE MEDIA • Based on bacterial metabolism* • Culture pH • Culture oxidation- reduction potential. • Gaseous requirements • Oxygen, Carbon dioxide and other gases DR.T.V.RAO MD 2
  3. 3. CULTURE MEDIA • Used to grow bacteria • Can be used to: • Enrich the numbers of bacteria • Select for certain bacteria and suppress others • Differentiate among different kinds of bacteria DR.T.V.RAO MD 3
  4. 4. OXYGEN CONCENTRATION • Aerobs • Anaerobs (do not require oxygen) • Obligate anaerobs (die in the presence of Ooxygen ) • Facultative anaerobs (E.coli) • Microaerophilic bacteria DR.T.V.RAO MD 4
  5. 5. PURPOSE OF CULTURING • Isolation • Properties of bacteria • To create antigens for laboratory use • Typing with Bacteriophages and Bacteriocins susceptibility • To test for Antibiotic sensitivity • Estimate viable counts • Maintain stock cultures DR.T.V.RAO MD 5
  6. 6. METHODS OF ISOLATION OF PURE CULTURE WITH .. • 1. Surface plating • 2 Enrichment medium • 3 Selective medium • 4 Indicator medium DR.T.V.RAO MD 6
  7. 7. TYPES OF MEDIA USED General purpose media will support the growth of many microorganisms. Enriched media are general purpose media supplemented by blood or other special nutrients to encourage the growth of fastidious heterotrophs; (fastidious = having complicated nutritional requirements DR.T.V.RAO MD 7
  8. 8. TYPES OF MEDIA USED Selective media favor the growth of particular microorganisms and inhibits the growth of others. Differential media distinguish between different groups of bacteria on the basis of their biological characteristics; Causes observable change in medium when biochemical reaction occurs DR.T.V.RAO MD 8
  9. 9. TEMPERATURE ( CHARACTERISTIC RANGES) • Psychrophiles: with optimum growth T around 20 C • Mesopihles: between 15 and 45 with optimum around 37 C • Thermophiles: between 30 and 75 with optimum around 55 C • Hyperthermophiles: T grater than 100C DR.T.V.RAO MD 9
  10. 10. TEMPERATURE AND BACTERIAL GROWTH DR.T.V.RAO MD 10
  11. 11. DR.T.V.RAO MD 11
  12. 12. THE REQUIREMENTS FOR GROWTH: PHYSICAL REQUIREMENTS • pH • Most bacteria grow between pH 6.5 and 7.5 • Molds and yeasts grow between pH 5 and 6 • Acidophilic grow in acidic environments DR.T.V.RAO MD 12
  13. 13. CULTURING • Used to grow bacteria • Can be used to: • Enrich the numbers of bacteria • Select for certain bacteria and suppress others • Differentiate among different kinds of bacteria DR.T.V.RAO MD 13
  14. 14. METHODS TO ISOLATE THE BACTERIA • Streak culture • Stroke • Stab • Pour plate • Liquid culture • Special methods for anaerobic cultures DR.T.V.RAO MD 14
  15. 15. How to inoculate a plate HOW TO INOCULATE A CULTURE PLATE • Plate: provide large surface for isolation and observation of colonies • Using a sterile loop or a sterile swab streak your sample on the Petri plate • Important let your sterilized loop cool before you pick up your sample DR.T.V.RAO MD 15
  16. 16. DIFFERENT METHODS OF CULTURING BACTERIA DR.T.V.RAO MD 16
  17. 17. MACCONKEY AGAR • Example:: MacConkey agar has color indicator that distinguishes presence of acid. Bacteria that ferment a particular sugar (e.g., glucose in culture media) will produce acid wastes on plates, turn pH indicator red. DR.T.V.RAO MD 17
  18. 18. COLONIES - MAKE A OBSERVATION • Shape • Size • Elevation • Edge • Surface • Opacity • Consistency DR.T.V.RAO MD 18
  19. 19. LIQUID MEDIA Liquid media: easiest to prepare and use. Good for growing quantities of microbes needed for analysis or experiments. Unless inoculated with pure culture, cannot separate different organisms. DR.T.V.RAO MD 19
  20. 20. SLANT OBSERVATION http://www.rlc.dcccd.edu/MATHSCI/reynolds/MICRO/lab_manual/slant_patterns.jpg DR.T.V.RAO MD 20
  21. 21. STREAK CULTURE • Lawn or carpet culture to create uniform surface of organisms • Bacteriophages typing • To obtain large amount of antigens DR.T.V.RAO MD 21
  22. 22. CULTURING THE MICROBES NEEDS SKILLS DR.T.V.RAO MD 22
  23. 23. STREAK PLATE DR.T.V.RAO MD 23 Figure 6.10a–b
  24. 24. METHODS OF ISOLATION OF PURE CULTURE • 1. Surface plating • 2 Enrichment medium • 3 Selective medium • 4 Indicator medium DR.T.V.RAO MD 24
  25. 25. LIQUID CULTURING • Liquid cultures are done in • Tubes • Bottles • Flasks • Blood culture • Water analysis DR.T.V.RAO MD 25
  26. 26. STAB CULTURE • Puncturing suitable medium such as nutrient agar, gelatin, • Observe gelatin liquefaction • Preserving the stock culture. DR.T.V.RAO MD 26
  27. 27. SWEEP PLATE METHOD DR.T.V.RAO MD 27
  28. 28. MICROBIAL ANTIBIOTIC SUSCEPTIBILITY TEST (THE AGAR DIFFUSION TEST ) Zones of growth inhibition DR.T.V.RAO MD 28
  29. 29. MULLER HINTON AGAR FOR ANTIBIOTIC TESTING DR.T.V.RAO MD 29
  30. 30. MEASURING THE ZONE OF INHIBITION DR.T.V.RAO MD 30
  31. 31. MINIMUM INHIBITORY CONCENTRATION DETECTS ANTIBIOTIC SENSITIVITY PATTERNS DR.T.V.RAO MD 31
  32. 32. • Anaerobic Bacterial Isolation and Identification Needs specified conditions DR.T.V.RAO MD 32
  33. 33. DESICCATOR • In Desiccator some oxygen is left Not suitable for fluid culture Displacement of oxygen is done with Hydrogen Nitrogen Helium Co2 DR.T.V.RAO MD 33
  34. 34. CANDLE JAR • Inoculated plates are kept • Burning candle use up all oxygen • But a little o2 is left • But presence of Co2 stimulates the most bacterium DR.T.V.RAO MD 34
  35. 35. MAC IN TOSH FILDES ANAEROBIC JAR • Contain inlet and outlet • Electrical supply • Inoculated culture plates • When electrified palladinised asbestos heating acts as catalyst for combination of hydrogen with residual oxygen causes complete anaerobiasis DR.T.V.RAO MD 35
  36. 36. GAS PACK • A disposable envelop contains chemicals which generate hydrogen and carbon dioxide on addition of water • Inoculated plates are kept in jar • Water is added hydrogen and carbon dioxide are liberated • Presence of cold catalyst in the envelop permits the combination of Hydrogen and oxygen to produce anaerobic environment • Indicator is methylene blue • Colorless when anaerobic environment. DR.T.V.RAO MD 36
  37. 37. OTHER REDUCING AGENTS • Reducing agents O.1% Thiglyclolate 0.1% Ascorbic acid 0.05 % cysteine DR.T.V.RAO MD 37
  38. 38. ROBERTSON COOKED MEAT MEDIUM ROUTINELY USED IN ANAEROBIC SPORE BEARING BACTERIA DR.T.V.RAO MD 38
  39. 39. DR.T.V.RAO MD 39
  40. 40. LOWENSTEIN JENSEN MEDIUM - CULTIVATION OF MYCOBACTERIUM TUBERCULOSIS DR.T.V.RAO MD 40
  41. 41. WORKING WITH MYCOBACTERIUM NEEDS BIOSAFTEY CONCERNS DR.T.V.RAO MD 41
  42. 42. • Created by Dr.T.V.Rao MD for Basic learning on Culturing Bacteria for Medical and Paramedical students in Microbiology • Email • doctortvrao@gmail.com DR.T.V.RAO MD 42

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