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Koch's Postulates

This protocol allows students to demonstrate and test Koch’s Postulates using apples infected with the fungus Penicillium expansum. The required experimental work extends over 3 to 4 weeks, but the essential steps can be demonstrated in a single practical session if students are provided with cultures and infected fruit which represent different stages in the sequence of steps.

In his work on diseases, Robert Koch was trying to establish whether a microbe, obtained from a diseased patient, was in fact the cause of the disease. This led him to formulate ‘Koch’s Postulates’ - a set of conditions which need to be fulfilled to establish which organism is causing a particular disease.

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