Lab 3 culture media 2012
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Lab 3 culture media 2012






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Lab 3 culture media 2012 Lab 3 culture media 2012 Presentation Transcript

  • Second year Lab Medicine (Females) 1433- 1434 A.H. / 2012- 2013 Microbiology Practical (Course I).Mrs. Hibah Abdul-Wahab I Abu-Sulaiman
  • Who will be her groom??!
  • Royal Dining Royal Atmosphere
  •  Bacterial nutritional requirements. Composition of culture media. Categories of culture media. Solidifying agents. Types of media. Media Quality control.
  • 1. Carbon Source: ◦ Heterotrphs: from organic compounds such as: a.a., polysaccharides, CHO, proteins and peptides. ◦ Autotrophs: from fixing inorganic carbon dioxide.1. Energy Source: ◦ Phototrophs: from sunlight. ◦ Chemotrophs: from oxidation of chemicals.1. Nitrogen: essential for a.a., nucleotide and vitamins synthesis.
  • 4. Minerals: as cofactors in enzymatic reactions. ◦ E.g., sodium, potassium, calcium, magnesium, iron… etc.4. Growth factors: ◦ Amino acids, a.a.: bacteria possess proteinases. ◦ Purines and pyrimidines: to be converted to nucleotides. ◦ Bacterial vitamins: for co-enzyme production.4. Water: ◦ All metabolic functions of a bacterial cell are performed in aqueous environment. ◦ Distilled water  Tap water minerals and their reaction with peptones and meat extracts.
  • 1. Water.2. Peptone: product of protein hydrolysis. ◦ From animal proteins: source of nitrogen. ◦ From soya bean (plant) protein: source of carbohydrates, CHO.1. Meat extracts: as source of a.a. and other essential vitamins and elements.2. Yeast extract: as a stimulant for bacterial growth in the media.3. Mineral salts: for bacterial enzymes activity.4. Carbohydrates: as source of carbon and energy.
  •  Agar: ◦ Is a complex polysaccharide (polymer of galactose) that is extracted from the cell wall of seaweed (red algae). ◦ It melts at 100oC and at 37oC it is solid. ◦ It has no nutritional value in agar cultures. ◦ It is added in a concentration of 1.5% to solidify media and 0.4% to make semisoft media. Gelatin: ◦ A protein which is derived from collagen of skin and bone. ◦ Some bacteria are able to liquefy gelatin at 37 oC.
  • Consist of Without agar With agar In the form of Can be in the form ofPrimarily used for Primarily used for
  • Agar Slant Agar Deep Agar Plates
  •  In broths, bacterial growth is indicated by a change in the appearance from clear to turbid (cloudy). Turbidity of the broth is due to light deflected by bacteria present in the culture. The more turbid, the….
  •  Basal Media: ◦ Simple media that will support the growth of most bacteria that do not require special nutrient. E.g., Nutrient broth. ◦ Nutrient broth+ agar= Nutrient agar Enriched media: ◦ Culture media that are enriched with whole or lysed blood, serum, special extracts or nutrient to support the growth of those bacteria that cannot grow on the basal media. ◦ Nutrient agar+ blood= Blood agar ◦ Blood agar+ heat= chocolate agar Selective media: ◦ Solid media which contain substances that inhibit the growth of some bacteria and letting the pathogenic ones grow.
  •  Enrichment media: ◦ These are liquid media that are similar in function to ... ◦ The only difference is that… Differential media: ◦ Contains indicators that will differentiate one organism from another Transport media: ◦ Contain substances that can prevent overgrowth of commensals and prevent bacteria from dying as a result of change in pH or enzyme action.
  •  Media should be tested for: 1. Sterility. 2. Each medium must be tested with organisms expected to grow or give a positive reaction as well as with organisms expected not to grow.
  •  In a table, define each of the following media sugar, inhibitors, indicators and other additives: 1. Bile Esculin Agar (BEA). 2. Blood Agar. 3. Chocolate Agar. 4. Cysteine-tellurite Agar. 5. MacConkey Agar. 6. Mannitol Salt Agar. 7. Salmonella-Shigella Agar. 8. Selenite broth. 9. Thayer-Martin Agar. 10. Thiosulfate Citrate-bile salts (TCBS) Agar. 11. Xylose lysine deoxycholate (XLD) agar.