MT

• CULTURE MEDIA

  • is a solid or liquid preparation used to grow, transport, and store microorganisms
• MEDIA

  • Mostly designed for bacteria and fungi
  • providing nutrients in the laboratory
• USES OF CULTURE MEDIUM

  1. To identify the cause of infection
  2. To study the characteristics
  3. prepare biological products
• Water

  • dissolve materials to be transported across cytoplasmic membrane
• Carbon

  • for the construction of all organic molecules
  • Usually glucose
• Nitrogen

  • Examples: Proteins, Beef extract
• Buffer System

  • bacteria grow at pH 7.0. This is achieved by using a…
• Physical States Of Media

  • Liquid Media
  • Semisolid Media
  • Solid Media
• Chemical Composition of Media

  • Synthetic
  • Non-synthetic
• Functional Type of Media

  • Enriched Medium
  • Selective
  • Differential
  • Specimen Transport
  • Assay
  • Enumeration
• Liquid Media

  • Water-based solutions that do not solidify at temperatures above freezing and that tend to flow freely when the container is tilted
  • Termed also as “broths, milks, or infusions” – are made by dissolving solutes in distilled water
• Liquid Media

  • Ecamples: Nutrient Broth, Methylene Blue Milk and Litmus Milk, Fluid Thioglycollate
• Semi-solid Media

  • Exhibit a clot-like consistency under ordinary room temperature due to presence of solidifying agent (agar or gelatin)
  • Used to determine the motility of bacteria and to localize a reaction at a specific site
• Liquid Media

  • Growth appearance: dispersed, cloudy, or flaky
• Semi-solid media

  Examples:Motility test medium, Sulfur indole motility (SIM) medium
• Solid Media

  • Provide a firm surface on which cells can form discrete colonies
  • Good for isolating and culturing bacteria and fungi
• Liquefiable solid media

  • Sometimes called “reversible solid media”
  • Contains solidifying agent that changes its physical properties in response to temperature
• Non-liquefiable solid media

  • Do not melt
  • Materials included are rice grains (use to grow fungi, cooked meat media (good for anaerobes),(permanently coagulated by moist heat
• General-purpose media

  • Designed to grow a broad spectrum of microbes that do have special growth - requirements
  • Non-synthetic (complex) and contain a
  • mixture of nutrients that could support the growth of variety of bacteria and fungi
• General purpose Media

  • Examples: nutrient agar and broth, brain-heart inclusion, and Trypticase Soy Agar (TSA)
• TSA

  • is a complex medium that contains artificially digested milk protein (casein), soybean digest, NaCl, and agar
• Enriched Medium

  • Contains complex organic substances such as blood, serum, hemoglobin, or special growth factors:
• Growth factors

  • Provided in species in order to grow
  • Are organic compounds such as vitamins and amino acids that the microbes cannot synthesized themselves
• Blood Agar

  • made by adding sterile animal blood to a sterile agar base
• Selective and Differential Media

  • Cleverest and most inventive media recipes
  • Designed for special microbial groups
  • Have extensive applications in isolation and identification
• Selective Media

  • Examples: Mannitol Salt Agar (MSA), MacConkey Agay & Hektoen Enteric Agar (HE)
• Differential Media

  • Grow several types of microorganisms but are designed to bring out visible differences among those microorganisms
• Dyes

  • are considered to be effective for differential agents because their pH indicators that color in response to the production of an acid or a base
• Selective Media

  • Contains one or agents that inhibit the growth of a certain microbe or microbes
  • Very important in primary isolation
  • Hasten isolation by suppressing the unwanted background organisms and allowing growth of the desired ones
• Specimen Transport Media

  • Used to maintain and preserve specimens that have to be held for a period of time before clinical analysis or to sustain delicate species that die rapidly if not held under stable condition
• Assay Media

  • Used by technologists to test the effectiveness of antimicrobial drugs and by drug manufacturers to assess the effect of disinfectants, antiseptics, cosmetics, and preservatives on the growth of microorganisms
• Enumeration Media

  • Used by industrial and environmental microbiologists to count the numbers of organisms in milk, water, food, soil and other samples
• INOCULATION

  • Placing a sample into a container of medium that supplies nutrients for growth and is the first stage in culturing
  • To increase visibility; makes it possible to handle and manage microbes in an artificial environment
• INCUBATION

  • Exposing the inoculated medium to optimal growth conditions,
  • To promote multiplication and produce the actual culture.
• ISOLATION

  • Methods for separating individual microbes and achieving isolated colonies that can be readily distinguished another macroscopically
  • To make additional cultures from single colonies to ensure they are pure;
• INSPECTION

  • Observing cultures macroscopically for appearance of growth and microscopically for appearance of cells
  • To analyze initial characteristics of microbes in samples;
• INFORMATION AND GATHERING

  • Testing of cultures with procedures that analyze biochemical and enzyme characteristics, immunologic reactions, drug sensitivity, and genetic makeup
  • To provide much specific data and generate an overall profile of the microbes.
• IDENTIFICATION

  • Analysis of collected data to help support a final determination of the types of microbes present in the original sample.
  • This lays the groundwork for further research into the nature and roles of these microbes;
• Inoculation

  • The sample is placed into a container of sterile medium that provides microbes with the appropriate nutrients to sustain growth.
  • involves using a sterile tool to spread the sample on the surface of a solid medium or to introduce the sample into a flask or tube.
• Culture

  • an observable growth that appears in or on the medium after incubation