Take the test tube that contains the mixed culture; shake it to homogenize its content. Flame the inoculation loop and take a sample of the culture. Flame the mouth of the test tube when it is opened and before it is closed.

On a nutrient agar plate, gently touching the surface of the culture medium spread the sample following the diagram in the figure. The route of the loop must be as long as possible in order to isolate cells that will form colonies at the end of it. When the lid is taken off the Petri dish, keep the lid in your hand, and just keep it open for the inoculation. After inoculating the dish put the lid back on it and turn it upside down to incubate at 37ºC..

After 24 hours of incubation colonies formed by the different types of microorganisms of the mixed culture with their different characteristics can be observed. A higher density of growth is observed at the beginning of the streaking, where the colonies cannot be distinguished, however, at the end of this the colonies are isolated better and the difference between them, such as the size, the color and shape can be made out.

Growth of bacterial colonies using the inoculation loop streaking technique.

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