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  • Streak-Plate Method:

  • Streak plate method is a pure culture technique which helps in isolating desired colonies

  • from contaminants. The procedure begins by sterilizing a wire

  • loop in flame. Cool the sterilized loop by allowing it to

  • stand for a few seconds. Dip the loop into a sample containing a mixture

  • of bacteria. Depending on the sample, the loop may pick up hundreds or thousands of

  • bacteria, which are spread back and forth across the surface of the agar.

  • Make a uniform smear with the inoculum at the edge of the plate.

  • Sterilise the loop as mentioned above, and make streaks from the smear.

  • Since there is thinning of inoculum during streaking, isolated colonies are formed at

  • ideal streak point where the spreading has separated the individual (or group) of cells

  • at locations where they can form individual colonies

  • The pattern of streaking varies with different type of streak plate techniques, for e.g.

  • Quadrant streak, T-streak etc. During the incubation, the bacteria multiply

  • and produce colonies. Intermittent flaming of the loop can be done

  • during streaking to reduce the load of the organism so that there is a better chance

  • of getting isolated colonies. Keep the plate covered as much as possible

  • to avoid contamination While streaking a section of the plate, try

  • to keep the inoculating loop in contact with the surface of the agar at all times.

Streak-Plate Method:

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