Which of the following methods is NOT a form of isolation on a petri dish?

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Prepare for the UCF General Microbiology Lab Midterm Exam. Study using flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

The method of isolation that is not performed on a petri dish is the slant culture. Slant cultures are created in test tubes that contain agar that has been solidified at an angle, creating a slanted surface where microorganisms can be inoculated and grown. This technique is commonly used for maintaining microbial cultures and for storage purposes, rather than for isolating single colonies from a mixture.

In contrast, the three-zone streak plate, spread plate, and pour plate methods all utilize petri dishes and are specifically designed to isolate individual colonies from a mixed culture. The three-zone streak plate involves streaking a loopful of culture in three sections to achieve dilution across the agar surface, while the spread plate method distributes a diluted microbial sample evenly across the surface using a glass spreader. The pour plate technique involves mixing diluted samples with molten agar and then allowing them to solidify in a petri dish, resulting in colonies growing both on the surface and within the agar. These techniques focus on achieving isolation, making them suitable for use in petri dishes.