Bacterial Isolation on Petri Dish – Biology Lab Techniques

Bacterial Isolation on Petri Dish – Biology Lab Techniques


Start by cleaning and sterilizing the workspace. Spray once with 10% Milton and wipe thoroughly using clean tissue paper. Repeat twice, but with 70% ethanol. A diluted 70% solution of ethanol is actually a more potent disinfecting agent than pure ethanol. One of the goals of growing Bacteria on solid medium is to grow individual colonies made of a single clone. Plates can also be used for short-term storage in the fridge up to 3 weeks. Light up the Bunsen burner to establish a cone of sterility. Hot air creates an upwards current that prevents airborne contaminants from falling onto your work. Make sure you conduct all of your sterile work within that zone. Spray your hands with 70% ethanol to sterilize their surface. If you opt for wearing gloves proceed in the same manner. Sterilize your loop in the flame. The hottest part of the flame is located just above the tip of the blue cone. Let your loop cool down. To ensure proper cooling stabbed your loop in a clean part of the medium once or twice. Pick up a single colony by touching it with your loop. Streak a clean Petri dish using the quadrant method. The goal is to reduce the bacterial load at every streak to separate single bacterial cells. Do not let the loop go back into the previous quadrants for most of the original inoculum was deposited. Here is a visualization of the streaky made using a marker. Sterilize your loop using the flame watch out for projections due to boiling of remaining material on your loop. Remember that you should wear protective eyewear whenever using the Bunsen burner. Label the back of your plate using a permanent partner. Use Para film to seal the Petri dish in order to Avoid excessive evaporation during incubation. Parafilm also lets gas through which allows aerobic respiration throughout the incubation period. Incubate your plate upside down overnight. Pick up your plates on the next morning and look for single colonies. This is an overnight culture of Escherichia coli. Thanks for watching, please subscribe to our channel for more science videos.

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